Preparation method of composite fluorescent whitening agent

Abstract

The invention belongs to the technical field of detergents, and particularly relates to a preparation method of a composite fluorescent whitening agent. The method comprises an acylation reaction, a sulfonation reaction, a carbonyl reduction reaction, a dehydration reaction and a sulfonic acid salification reaction. Compared with a commercially available fluorescent whitening agent such as CBS, the composite fluorescent whitening agent synthesized by the preparation method disclosed by the invention has similar application effects, but the preparation process disclosed by the invention is simple, low in cost, environment-friendly in route and environment-friendly in working environment.

Description

Technical Field

[0001] The present application relates to the technical field of detergents, and in particular to a method for preparing a composite fluorescent whitening agent. Background Art

[0002] Compared with diphenylethylene bistriazine fluorescent whitening agents, distyryl biphenyl fluorescent whitening agents have good water solubility and good whitening effects on cotton fabrics, polyester fibers, protein fibers, acetate fibers, etc. They are also excellent whitening additives for detergents, laundry detergents, cosmetics, etc., so they are widely used. At present, the most widely used product at home and abroad is fluorescent whitening agent CI351, with trade names CBS-X, FB-351, etc. However, there are many problems in the preparation of distyryl biphenyl fluorescent whitening agents. For example, the manufacturing cost and the cost of three waste treatment are high, and the yield is not ideal. Summary of the invention

[0003] The purpose of the present application is to provide a method for preparing a composite fluorescent whitening agent. The method is conducive to more conveniently preparing a composite fluorescent whitening agent.

[0004] On the one hand, the present application provides a method for preparing a composite fluorescent whitening agent, comprising the following steps: Step 1: Acylation reaction Using phenylacetyl chloride and biphenyl as raw materials, adding aluminum chloride, an acylation reaction occurs in the absence of solvent or in the presence of a solvent to obtain an acylated product 4,4'-diphenylacetylbiphenyl; Step 2: Sulfonation reaction The acylated product 4,4'-diphenylacetylbiphenyl obtained in step 1 is added to sulfuric acid for sulfonation reaction to obtain a sulfonated product; the sulfonated product comprises a 2,4'-sulfonated product and a 4,4'-sulfonated product; Step 3: Carbonyl reduction The sulfonated product obtained in step 2 is reacted under reducing agent conditions to obtain a reduced product; Step 4: Dehydration reaction The reduced product obtained in step 3 is subjected to a dehydration reaction to obtain a dehydrated product; Step 5: Sulfonic acid salt formation reaction The dehydrated product obtained in step 4 is added to the salt reaction solution and stirred for a certain period of time to obtain the final product.

[0005] In some embodiments, in the above step 2, Based on the total mass of the above sulfonated product, the mass percentage content of the above 2,4'-position sulfonated product is 80% to 90%; The mass percentage content of the above-mentioned 4,4'-position sulfonation product is 5% to 9%; The remainder includes any one or more of a 4,3'-sulfonated product, a 2,3'-sulfonated product, a 2,2'-sulfonated product, and a 3,3'-sulfonated product.

[0006] In some embodiments, based on the total mass of the sulfonated product, the mass percentage content of the 4,3'-position sulfonated product is less than or equal to 2.5%; and / or; The mass percentage content of the above-mentioned 2,3'-position sulfonation product is less than or equal to 2%; and / or; The mass percentage content of 2,2'-sulfonated products is less than or equal to 2.2%; and / or; The mass percentage content of the 3,3'-position sulfonation product is less than or equal to 0.5%.

[0007] In some embodiments, in the above step 2, the mass percentage concentration of the above sulfuric acid is greater than 90%.

[0008] In some embodiments, the molar ratio of the acylated product 4,4'-diphenylacetylbiphenyl to sulfuric acid is 1:6-12.

[0009] In some embodiments, the solvent in step 1 above includes any one or more of dichloromethane, tetrahydrofuran, cyclohexane, n-hexane, 1,2-dichloroethane, n-cycloheptane, petroleum ether, solvent oil, light oil, sulfonated kerosene or nitrobenzene; and / or; The molar ratio of the phenylacetyl chloride to biphenyl is 2.2-2.6:1-2; and / or; The molar ratio of the aluminum chloride to biphenyl is 2.2-3.0:1-2; and / or; The mass ratio of the solvent to biphenyl is 2-10:1.

[0010] In some embodiments, the solvent in step 1 above further includes a pretreatment step, which includes adding the solvent to fuming sulfuric acid, stirring it thoroughly and then letting it stand, and taking the upper organic phase as the solvent for the acylation reaction.

[0011] In some embodiments, the reducing agent in step 3 above includes any one or more of hydrogen, sodium borohydride, aluminum isopropoxide / isopropanol, platinum carbon / hydrogen, palladium carbon / hydrogen, and nickel / hydrogen.

[0012] In some embodiments, the dehydration reaction in step 4 is carried out in sulfuric acid, and the mass percentage concentration of the sulfuric acid is 40% to 80%.

[0013] In some embodiments, the reduction reaction in step 3 and the dehydration reaction in step 4 are a one-step reaction.

[0014] In some embodiments, in step 5, the mass of the dehydrated product is 10% to 20% of the mass of the salt.

[0015] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below.

[0016] Beneficial technical effects of this application: (1) The composite fluorescent brightener prepared by the preparation method provided in this application has similar application effects to the fluorescent brightener CBS on the market, but has the advantages of simple preparation process, low cost, environmentally friendly route and friendly working environment.

[0017] (2) The sulfonation reaction in the preparation method provided in this application can control the sulfonic acid to be only on the benzene ring, and the biphenyl ring is controllable. The benzene ring has three positions to choose from: the ortho and meta pairs have a certain ratio, so the sulfonation reaction can obtain sulfonates at several positions of the two benzene rings. The product obtained by this uneven distribution has the functions of complementary advantages, composite synergy, and improved dyeing rate in the subsequent use of fluorescent whitening agents.

[0018] (3) The preparation process of the present application does not contain phosphorus and its phosphorus derivatives, thus successfully reducing this environmentally polluting compound. At the same time, the present application does not use dimethylformamide, an organic solvent that is difficult to recycle and pollutes, in production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: Figure 1 This is a flow chart of the steps of the preparation method of some embodiments of the present application. DETAILED DESCRIPTION

[0020] Hereinafter, the embodiment of the method for preparing the composite fluorescent whitening agent of the present application is specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0021] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that the range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0022] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0023] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0024] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0025] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0026] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0027] If not otherwise specified, in this application, the terms "first", "second", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary and secondary relationship of the indicated technical features.

[0028] Unless otherwise specified, in this application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0029] Unless otherwise specified, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present application.

[0030] If there is no special explanation, unless otherwise clearly specified and limited, technical terms such as "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0031] Compared with diphenylethylene bistriazine fluorescent brightener, distyryl biphenyl fluorescent brightener has good water solubility and has good whitening effect on cotton fabric, polyester fiber, protein fiber, acetate fiber, etc. It is also an excellent whitening additive for detergents, laundry detergents, cosmetics, etc., and is widely used. At present, the most widely used product at home and abroad is fluorescent brightener CI351, with trade names such as CBS-X and FB-351. However, there are many problems in the preparation of distyryl biphenyl fluorescent brightener.

[0032] The following disadvantages exist in the synthesis process of the intermediate: In the synthesis process of 4,4'-dichloromethylbiphenyl (as shown in the following formula), the oily viscous liquid separated in the process of treating and refining 4,4'-dichloromethylbiphenyl contains more impurities than these, so that its yield is less than 80%.

[0033] .

[0034] During the above reaction, impurities such as chloromethylation, condensation, and hydrolysis are produced. Impurities 1, 2, 3, and 4 are shown in the following formula: Impurity 1; Impurity 2; Impurity 3; Impurity 4.

[0035] At present, fluorescent brighteners used in laundry detergents and laundry soaps are all produced using phosphites as raw materials, and their manufacturing costs and three waste treatment costs remain high.

[0036] In addition, in actual production, the reaction may produce harmful substances that may cause allergies due to operational problems, raw material problems, etc., such as chloromethyl ether impurities generated by formaldehyde and hydrogen chloride in the system; aromatic and unsaturated olefin impurities in the solvent react with formaldehyde and hydrogen chloride to produce chloromethyl impurity benzyl compounds (as shown in the following formula). The removal of these compounds can cause people to tear and may cause allergic reactions in people with different physiques.

[0037] .

[0038] In the subsequent synthesis process, the above process still has the problem that ethyl chloride is produced, and the recovery needs to be frozen and compressed. In addition, the reaction is carried out by heating in the solvent, and the reaction is cooled down and precipitated, filtered and dried. The solvent will be lost in the drying process, which also has safety hazards.

[0039] .

[0040] In the synthetic reaction system of fluorescent whitening agent CBS, there are products, by-products, sodium diethyl phosphite and solvent dimethylformamide (DMF). In the past, dimethyl sulfoxide and methanol were used, which integrated organic phosphorus, ammonia nitrogen, organic matter, and metal salts. This brings difficulties to the subsequent solvent recovery (methanol, DMF). At the same time, the treatment of three wastes is difficult. When recovering process solvents, methanol with a low boiling point is relatively easy. However, when recovering dimethylformamide, due to the distillation of methanol, the concentration of the system increases, and the viscosity increases synchronously, and the distillation of DMF becomes more and more difficult. At this time, sodium diethyl phosphite and other sodium salts in the system (sodium methoxide is produced during the neutralization process) also increasingly affect the distillation. At the same time, the removal of the residual solids in the still after distillation is also a problem, and manual removal is often required.

[0041] .

[0042] The preparation method adopted in the present application avoids the problems existing in the current production process of fluorescent whitening agent CBS, and provides a more convenient preparation method of a composite fluorescent whitening agent that is easy for industrial production.

[0043] The following is an explanation and description of the terms used in this application: The structure of fluorescent brightener CBS is as follows: .

[0044] The process for manufacturing fluorescent brighteners in this application adopts Figure 1 The schematic diagram of the classic reactions: C-acylation; aromatic sulfonation; carbonyl reduction; dehydroxylation (water) to olefin reaction; (sulfonic acid) salt formation, etc. The specific preparation steps are shown in the following formula: .

[0045] Before forming a complete route, the present application has gone through exploration and attempts of various reaction routes, and the adopted attempts and exploration verification process or mechanism inference is as follows.

[0046] In the first step of the acylation reaction, the acylation reaction is mainly the selection of the reaction solvent. Because the reaction has high selectivity, the acylation route adopted in this application does not occur at the ortho position of biphenyl or multiple acylation, as shown below: .

[0047] In this application, not only did the acylation reaction of biphenyl 2,2'-position not occur, but also the 4,2'-position did not react, as shown below, .

[0048] During the acylation reaction of the present application, the phenylacetyl group is positioned at the 2-position on the biphenyl ring and the diacylation of the same parent body does not occur, as shown below: .

[0049] Finally, the following acylation preparation process was finally selected by this application: .

[0050] It can be seen from the reaction equation of the present application that as long as there is enough phenylacetyl chloride, the reaction can continue to occur to form a chain-type macromolecule.

[0051] In the second step of sulfonation, unlike the acylation reaction in the previous step, the acylation reaction is almost entirely at the 4.4'-position (two para positions) due to the positioning of biphenyl. In the sulfonation reaction of the acylated product, the biphenyl group is located at the meta position due to the carbonyl group, which is exactly the 2 position of biphenyl, that is, the ortho position, with large steric hindrance. Therefore, sulfonation mainly occurs on the benzene ring. The substitution reaction of the benzene ring is similar to toluene. The sulfonation reaction products are distributed in the ortho, meta, and para positions of the methyl group. This ratio is determined by factors such as the sulfonating agent (such as 100% sulfuric acid, fuming sulfuric acid, etc.), the reaction method, and the reaction temperature. According to the reaction process, the sulfonation reaction occurs successively on the two benzene rings:

[0052] This monosulfonated product can be verified by potassium permanganate oxidation (the confirmation of the isomers in the following isomer distribution table 2 is also based on the carboxybenzenesulfonic acid obtained by this oxidation):

[0053] That is, the synthesis of the disulfonated target compound, after the monosulfonation reaction is completed, the disulfonation reaction begins:

[0054] In fact, through monitoring during the reaction, it was found that disulfonation had already occurred when the monosulfonation product was not completely completed.

[0055] When the sulfonating agent is sufficient, excessive or the reaction temperature is high enough, the sulfonation reaction can occur on the biphenyl ring:

[0056] If the sulfonic acid on the benzene ring is in the meta position (relative to the methylene benzyl position), it is more difficult to add the second sulfonic acid.

[0057] The position selected for the sulfonation reaction has a great influence on the coloring effect and fluorescence intensity: the 2-position has high fluorescence intensity, and the 4-position and 3-position have high dyeing rates.

[0058] The 4,4'-position fluorescent brightener was prepared by replacing sodium benzaldehyde-2-sulfonate with sodium benzaldehyde-4-sulfonate:

[0059] The fluorescence intensity of the compound is slightly lower than that of the commercial fluorescent whitening agent CBS, but the coloring effect is greater than that of the fluorescent whitening agent CBS.

[0060] The following compounds were prepared by mixing sodium benzaldehyde-4-sulfonate and sodium benzaldehyde-2-sulfonate:

[0061] The dyeing effect and dyeing effect of this composite compound are between the above two, with no obvious difference.

[0062] In the third step, the reduction reaction aims to reduce the carbonyl group to a hydroxyl group (alcohol).

[0063]

[0064] If the temperature and pressure are too high, the amount of catalyst is too large, the activity is too high, the pH of the system is improper, etc., it will lead to over-reduction (equivalent to the product of Huang Minglong reaction). This deep reduction phenomenon cannot be seen by naked eyes in the hydrogen reduction reaction, but in the next step of the dehydration reaction, the reaction product has no fluorescence or the fluorescence is not obvious.

[0065]

[0066] The influence of different catalysts on the reduction reaction, such as platinum carbon, palladium carbon, nickel, etc. can catalyze the reduction of carbonyl to hydroxyl. In addition to over-reduction, excessive activity will make it more susceptible to poisoning or deactivation, and its carrying capacity is poor. High catalyst loss also constitutes a burden on the synthesis cost. Because the hydrogen reduction is carried out in an aqueous medium, the catalyst spontaneous combustion phenomenon does not occur. pH, that is, the acidity and alkalinity of the system, cannot be ignored. For example, too strong acidity will react with the catalyst first:

[0067] In the fourth step, dehydration to olefin reaction: Entering this reaction link is the last step of the product, and the reaction result is mainly affected by the previous steps. Entering the dehydration to olefin link is mainly the choice of acid concentration.

[0068] In summary, the present application discloses a method for preparing a composite fluorescent whitening agent, comprising the following steps: Step 1: Acylation reaction With phenylacetyl chloride and biphenyl as raw materials, aluminum chloride is added, and an acylation reaction occurs in the absence of solvent or in the presence of a solvent to obtain the acylated product 4,4'-diphenylacetylbiphenyl; the chemical reaction process is as follows: ; Step 2: Sulfonation reaction The acylated product 4,4'-diphenylacetylbiphenyl obtained in step 1 is added to sulfuric acid for sulfonation reaction to obtain a sulfonated product; the sulfonated product includes a 2,4'-sulfonated product and a 4,4'-sulfonated product; the chemical reaction process is as follows: ; Among them, the structure of the 2,4'-sulfonated product is as follows: ; The structure of the 4,4'-sulfonated product is as follows: ; Step 3: Carbonyl reduction The sulfonated product obtained in step 2 is reacted under reducing agent conditions to obtain a reduced product; The chemical reaction process is as follows: ; Step 4: Dehydration reaction The reduced product obtained in step 3 is subjected to a dehydration reaction to obtain a dehydrated product; The chemical reaction process is as follows:

[0069] ; Step 5: Sulfonic acid salt formation reaction The dehydrated product obtained in step 4 is added to the salt reaction solution and stirred for a certain period of time to obtain the final product.

[0070] The chemical reaction process is as follows:

[0071] .

[0072] In some embodiments, in the above step 2, Based on the total mass of the above sulfonated product, the mass percentage content of the above 2,4'-position sulfonated product is 80% to 90%; The mass percentage content of the above-mentioned 4,4'-position sulfonation product is 5% to 9%; The remainder includes any one or more of a 4,3'-sulfonated product, a 2,3'-sulfonated product, a 2,2'-sulfonated product, and a 3,3'-sulfonated product.

[0073] The present application discloses in these embodiments that the mass percentage content of the above-mentioned 2,4'-sulfonated product is any one of 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90% or any one of the above two ranges.

[0074] The present application discloses in these embodiments that the mass percentage content of the 4,4'-sulfonated product is any one of 5%, 6%, 7%, 8%, 9% or any one of the ranges of any two of the above.

[0075] The structural formulas of the remaining sulfonated products in this application are shown in the following table.

[0076]

[0077] In some embodiments, based on the total mass of the sulfonated product, the mass percentage content of the 4,3'-position sulfonated product is less than or equal to 2.5%.

[0078] In some embodiments, the mass percentage of the 2,3'-sulfonated product is less than or equal to 2%.

[0079] In some embodiments, the mass percentage of the 2,2'-sulfonated product is less than or equal to 2.2%.

[0080] In some embodiments, the mass percentage of the 3,3'-sulfonated product is less than or equal to 0.5%.

[0081] In some embodiments, in step 2 above, the mass percentage concentration of the sulfuric acid is above 90%.

[0082] In some embodiments, the molar ratio of the acylated product 4,4'-diphenylacetylbiphenyl to sulfuric acid is 1:6-12.

[0083] The present application discloses in these embodiments that the molar ratio of the acylated product 4,4'-diphenylacetylbiphenyl to sulfuric acid is any one of 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12 or any one of the ranges of any two of the above.

[0084] In some embodiments, the solvent in step 1 above includes any one or more of dichloromethane, tetrahydrofuran, cyclohexane, n-hexane, 1,2-dichloroethane, n-cycloheptane, petroleum ether, solvent oil, light oil, sulfonated kerosene or nitrobenzene.

[0085] In some embodiments, the molar ratio of phenylacetyl chloride to biphenyl is 2.2-2.6:1-2.

[0086] In some embodiments, the molar ratio of aluminum chloride to biphenyl is 2.2-3.0:1-2.

[0087] In some embodiments, the mass ratio of the above solvent to biphenyl is 2-10:1.

[0088] In these embodiments, the present application discloses that the molar ratio of phenylacetyl chloride to biphenyl is any one of 2.2:1, 2.2:1.5, 2.2:2, 2.6:1, 2.6:1.5, 2.6:2 or any one of the ranges of any two of the above.

[0089] In these embodiments, the present application discloses that the molar ratio of the aluminum chloride to biphenyl is any one of 2.2:1, 2.2:1.5, 2.2:2, 2.6:1, 2.6:1.5, 2.6:2, 3.0:1, 3.0:1.5, 3.0:2 ​​or any one of the ranges of any two of the above.

[0090] The present application discloses in these embodiments that the mass ratio of the above-mentioned solvent to biphenyl is any one of 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or any one of the ranges of any two of the above-mentioned values.

[0091] In some embodiments, the solvent in step 1 above further includes a pretreatment step, which includes adding the solvent to fuming sulfuric acid, stirring it thoroughly and then letting it stand, and taking the upper organic phase as the solvent for the acylation reaction.

[0092] In some embodiments, the reducing agent in step 3 above includes any one or more of hydrogen, sodium borohydride, aluminum isopropoxide / isopropanol, platinum carbon / hydrogen, palladium carbon / hydrogen, and nickel / hydrogen.

[0093] In some embodiments, the dehydration reaction in step 4 is carried out in sulfuric acid, and the mass percentage concentration of the sulfuric acid is 40% to 80%.

[0094] The present application discloses in these embodiments that the dehydration reaction in the above step 4 is carried out in sulfuric acid, and the mass percentage concentration of the sulfuric acid is any one of 40%, 50%, 60%, 70%, 80% or any one of the ranges of any two of the above.

[0095] In some embodiments, the reduction reaction in step 3 and the dehydration reaction in step 4 are a one-step reaction.

[0096] In some embodiments, in step 5 above, the mass of the dehydrated product is 10% to 20% of the mass of the salt.

[0097] In these embodiments, the present application discloses that the mass of the above-mentioned dehydration product is any one of 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20% of the mass of the above-mentioned salt, or any one of the values ​​in any two ranges thereof.

[0098] To make the purpose, technical solution and advantages of the present application clearer, the interference of the secondary battery protected by the present application is described in detail below in conjunction with specific embodiments. The chemical substances, reagents, etc. used in the following embodiments are all of any conventional models and manufacturers in the art.

[0099] Example A method for preparing a composite fluorescent whitening agent is provided, and the method comprises the following preparation process: (1) Acylation reaction - using phenylacetyl chloride as the acylating agent: Acylation reaction 1: In a three-necked flask, add phenylacetyl chloride, add biphenyl at room temperature and stir to dissolve, the molar ratio of phenylacetyl chloride to biphenyl is 2.4:1, cool to -10°C, add aluminum chloride in batches (the molar ratio of aluminum chloride to biphenyl is 3.0:1), keep warm for a period of time after addition, release hydrogen chloride by reaction, absorb it with sodium hydroxide, ammonia water, sodium carbonate, etc., place the reaction material in ice water, stir, filter, wash and dry to obtain an acylation product, the acylation product includes 4,4'-diphenylacetylbiphenyl (acylate), and the acylate content in the product is greater than 98%, wherein the content detection method includes any conventional method in the art such as liquid chromatography.

[0100] Acylation reaction 2 Provided is a preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) that is the same as the acylation reaction 1. The difference between the preparation method and the acylation reaction 1 is that a solvent dichloromethane is also added, and the mass ratio of dichloromethane to biphenyl is 5:1. After the reaction is completed, the reaction material is placed in ice water, stirred, and allowed to stand. The upper layer of water is separated with a separatory funnel, washed with water to pH=7, the dichloromethane solution is concentrated, and after distilling part of the dichloromethane, the temperature is lowered, the acylated product is partially separated, and filtered (no high vacuum can cause dichloromethane loss). The filtrate and the distilled dichloromethane are used for the next dilution and reaction respectively. After the filter cake is air-dried, the single batch yield is about 80%, and after 5 batches are applied, it is greater than 85%, and the acylated content in the product is greater than 98.5%.

[0101] Acylation reaction 3 Provided is a preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1. The difference between the preparation method and the acylation reaction 1 is that a solvent tetrahydrofuran is further added (and the mass ratio of tetrahydrofuran to biphenyl is 2:1). After the filter cake obtained by filtration is air-dried, the single batch yield is about 80%. After 5 batches of mother liquor are filtered and tetrahydrofuran is distilled out for recovery, the yield can be greater than 86%, and the acylated product content in the product is greater than 98.5%.

[0102] Acylation reaction 4 Provided is a preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1. The difference between the preparation method and the acylation reaction 1 is that a solvent cyclohexane is further added (and the mass ratio of cyclohexane to biphenyl is 10:1). After the filter cake obtained by filtration is air-dried, the single batch yield is greater than 78%, and after 5 batches of application, it is greater than 86%, and the acylated product content in the product is greater than 98.4%.

[0103] Acylation reaction 5 Provided is a preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1. The preparation method is different from the acylation reaction 1 in that a solvent, n-hexane, is further added. After the filter cake obtained by filtration is air-dried, the single batch yield is greater than 79%, and after 5 batches are applied, it is greater than 85%, and the acylated product content in the product is greater than 98.5%.

[0104] Acylation reaction 6 Provided is a preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1. The preparation method is different from the acylation reaction 1 in that a solvent 1,2-dichloroethane is further added. After the filter cake obtained by filtration is air-dried, the single batch yield is greater than 80%, and after 5 batches are applied, it is greater than 86%, and the acylated product content in the product is greater than 98.5%.

[0105] Acylation reaction 7 A method for preparing an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1 is provided. The difference between the preparation method and the preparation example 1 is that a solvent, n-cycloheptane, is further added. After the filter cake obtained by filtration is air-dried, the single batch yield is greater than 80%, and after 5 batches are applied, the yield is greater than 86%, and the acylated product content in the product is greater than 98.4%.

[0106] Acylation reaction 8 Provided is a preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1. The difference between the preparation method and the acylation reaction 1 is that a solvent petroleum ether is also added. Pretreatment: petroleum ether is slowly added to a 2% to 3% oleum (prepared from 20% oleum and 98% sulfuric acid) prepared in advance, stirred thoroughly and allowed to stand, and the upper organic phase is taken as a solvent for acylation reaction. After the filter cake obtained by filtration is air-dried, the single batch yield is greater than 80%, and after 5 batches are applied, it is greater than 86%, and the acylated content in the product is greater than 98.5%.

[0107] Acylation reaction 9 Provided is a preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1. The preparation method is different from the acylation reaction 1 in that solvent oil is further added. The pretreatment is the same as the above acylation reaction 8. After the filter cake is air-dried, the single batch yield is greater than 80%, and after 5 batches are applied, it is greater than 86%, and the acylated content in the product is greater than 98.5%.

[0108] Acylation reaction 10 Provided is a preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1. The preparation method is different from the acylation reaction 1 in that light oil is further added. After the filter cake obtained by filtration is air-dried, the single batch yield is greater than 80%, and after 5 batches are applied, it is greater than 86%, and the acylated product content in the product is greater than 98.5%.

[0109] Acylation reaction 11 Provided is a preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1. The preparation method is different from the acylation reaction 1 in that sulfonated kerosene is further added. After the filter cake obtained by filtration is air-dried, the single batch yield is greater than 80%, and after 5 batches are applied, it is greater than 86%, and the acylated content in the product is greater than 98.5%.

[0110] Acylation reaction 12 A preparation method of an acylated product 4,4'-diphenylacetylbiphenyl (finished acylated product) which is the same as the acylation reaction 1 is provided. The preparation method is different from the acylation reaction 1 in that nitrobenzene is further added. After the filter cake obtained by filtration is air-dried, the single batch yield is greater than 80.5%, and after 5 batches are applied, it is greater than 86.5%, and the acylated product content in the product is greater than 98.5%.

[0111] Among them, the screening of the above acylation reaction is as follows Table 1: Table 1 Screening of reaction solvents in acylation reaction

[0112] Note: For clarity, the decimal point is rounded up to 6, rounded to 4: for example, 95.4%=95%, 95.5%=95.5%, 95.6%=96%, and the rest of the numbers remain the same.

[0113] (2) Sulfonation reaction Sulfonation reaction 13 Take the acylation reaction products of the above acylation experiments 2 to acylation experiments 8, add the acylation products to industrial concentrated sulfuric acid (mass percentage concentration 98%) in a molar ratio of 1:6~12, add them to the concentrated sulfuric acid under stirring, and after they are completely dissolved, slowly heat them to 80~110°C, keep them warm for 2~8 hours, cool them down, and slowly pour them into crushed ice that can dilute the reactants to 20% sulfuric acid solution at room temperature of 15~25°C, stir until the floating ice is completely dissolved, add sodium chloride and potassium chloride to promote the precipitation of sulfonation products, stir for 4~8 hours, raise or lower the sulfonation material to room temperature, filter, wash several times with saturated sodium chloride aqueous solution, compact the material, and drain to obtain a sulfonation product, whose composition is mainly sulfonic acid at 2,4'-position and 4,4'-position (the position arrangement can be selected by controlling the reaction temperature), yield, quality and application indicators, which will be tested in subsequent experiments.

[0114] Table 2 List of acylated products

[0115] To confirm the isomers, the products can be oxidized with potassium permanganate to obtain 4,4'-biphenyldicarboxylic acid; o-carboxybenzenesulfonic acid (source of standard sample: sulfonation of o-chlorobenzoic acid and sodium sulfite); m-carboxybenzenesulfonic acid (sulfonation of benzoic acid and fuming sulfuric acid); and p-carboxybenzenesulfonic acid (oxidation of p-toluenesulfonic acid with potassium permanganate). The structure of the isomer can be confirmed based on the ratio of these oxidation products in liquid chromatography, combined with the liquid chromatography ratio of the raw materials in the previous step.

[0116] Sulfonation experiment 14~17 Repeat sulfonation experiment 13. After the reaction is completed, cool it to 0~5℃ and add it to crushed ice to make the remaining sulfuric acid equivalent to 30%, 40%, 50%, and 60% sulfuric acid solution for later use.

[0117] Sulfonation experiment 18 The acylation reaction products of acylation experiment 2 to acylation experiment 8 are added to 100% sulfuric acid (prepared with 98% sulfuric acid and 20% oleum) with a weight three times that of the product. The temperature is controlled at 0~10℃ throughout the process. After adding, stir until it is completely dissolved. When the temperature drops to 0℃, slowly add 100% sulfuric acid and 20% oleum, in which the oleum is in excess of 2~8%, and the volume ratio of 100% sulfuric acid is 1:1. When adding, the two are first mixed and dripped from the bottom of the liquid. Add oleum and 100% sulfuric acid. After stirring at 0~5℃ for 2~6 hours, remove the salt and ice water, stir for 2~6 hours, automatically heat to room temperature 15~25℃, and stir for another 2~4 hours. The reaction is over and enters the next stage of processing.

[0118] Slowly pour the sulfonation reaction materials (the temperature can be appropriately raised) into crushed ice with a concentration equivalent to 20%~50% of the remaining sulfuric acid that can be prepared for the reaction, stir (it is difficult to move at the beginning of stirring), and then cool it down with a salt ice water bath. During the cooling process, slowly add sodium chloride solid powder, stir for 2~6 hours, and filter after the material is precipitated. Wash, soak, and filter with saturated sodium chloride until the filtrate pH is 2~5, compact and vacuum, and constantly press and smash the cracks during the process, flatten, and set aside.

[0119] Sulfonation experiment 19 The conditions were the same as those of sulfonation experiment 18. The ingredients and proportions were adjusted by adding crushed ice cubes according to the multiple of the remaining sulfuric acid in the reaction to obtain a sulfuric acid solution equivalent to 90% to 4% of the remaining sulfuric acid in the system for use.

[0120] Table 3 List of acylated products

[0121] Sulfonation experiment 20 Take the reaction product solution of acylation experiment 9 to acylation experiment 12, wash it with sodium carbonate solution, remove the excess phenylacetic acid of phenylacetyl chloride hydrolyzate, then let it stand, dehydrate with sodium sulfate, place it in a reaction bottle, and slowly add 20% fuming sulfuric acid at 0~5℃ according to the molar ratio of sulfur trioxide to acylation product of 2.2~2.6. During the dropping process, stop when the temperature rises above 8℃, and add it again when the temperature drops below 5℃. It takes about two hours to add fuming sulfuric acid. During the process, it is necessary to pay attention to adding ice, salt and water to the ice bath to ensure the stability of the temperature. After the fuming sulfuric acid is added, the temperature of the system will no longer rise, and the temperature can be easily controlled at 5~10℃. After keeping warm for 2~4 hours, let it naturally warm up to room temperature, and stir for another 4~8 hours. Calculate the amount of ice according to the amount of sulfuric acid remaining in the reaction. After adding, it is equivalent to the sulfuric acid concentration of the system between 90% and 60%. When adding ice, pay attention to the system temperature not being higher than 60℃. When adding ice, use an ice bath to cool.

[0122] After adding the measured ice cubes, pour the reaction materials into the separatory funnel, extract the polytetrachloroethylene valve core in advance (heat it in 50℃ water), and place the separatory funnel in an enamel basin filled with 50℃ water. The enamel basin can be kept at a temperature of not less than 50℃ by replacing the hot water. After keeping warm and standing for 2-4 hours, put the lower layer of the separatory funnel into another preheated separatory funnel filled with 50 ml of toluene, stir it, and then stand it. Repeat about five times to wash away the solvent (the solvent of the acylated product).

[0123] The content composition of the sulfonation reaction product of the above preparation example is shown in Table 4: Table 4 List of acylated products

[0124] (3) Carbonyl reduction Reduction reaction 21 Take the precipitated material of the sulfonation reaction of the above sulfonation reaction experiment 13 and dissolve it in a certain amount of water, stir and dissolve, adjust the pH to 8~11 with sodium carbonate, stir and heat to 50~90℃, keep warm for 2~6 hours, add 1~5 grams of activated carbon, stir and cool to room temperature, filter, and adjust the filtrate to pH=6.5~8.5 with hydrochloric acid. Add the solution to a stainless steel autoclave not exceeding half the height of the autoclave, add a catalyst equivalent to 1% of the weight of the dry sulfonated product added to the reactor, cover the reactor lid, and tighten it. Replace the air with nitrogen three times, and test the pressure with nitrogen (the pressure does not drop for one hour) to prove that the reactor does not leak, and then replace the nitrogen with hydrogen. After three times, hydrogen is officially pressed in, and the reduction reaction stage is officially entered. In this process, each connection must be strictly checked, and the leak point can be checked with a foaming hand sanitizer. The pressure gauge pointer should be flexibly rotated with pressure increase or pressure relief.

[0125] After completing the preliminary preparation of the reaction pressure kettle, the experimental stage is carried out. Hydrogen is introduced through the pressure reducing valve. The pressure gauge pointer is stirred at the 1.8MPa position for ten minutes. Observe whether the pressure gauge pointer changes (retracts) and becomes smaller. If it decreases and retreats, it is supplemented to 1.8MPa. Gently tap the pressure gauge a few times to see if there is any change. After the pressure stabilizes, the temperature begins to rise. The temperature should be raised slowly in stages. At the same time, cooling water should be introduced into the cooling spring tube in the reactor. Once the temperature rises, it should be opened at any time and coordinated with heating. When the indoor temperature reaches 50℃, the pressure rises first and then falls, indicating that the reduction reaction has begun. Hydrogen is supplemented at any time during the period to stabilize the internal pressure at 1.8MPa. After several operations, the pressure in the reactor no longer decreases (this process takes 3 to 5 hours). When the temperature is cooled to room temperature after 2 to 6 hours of insulation, hydrogen is slowly released from the drain valve to the outside. At this time, the pressure gauge of the reactor should have a significant rotation and decline phenomenon. When it reaches zero (lowest point), close the vent valve, replace the nitrogen at the air inlet, open the pressure reducing valve, and add nitrogen to the reactor. At this time, the pressure gauge of the reactor is clearly visible, the pointer turns to 0.1~0.2 and stops, and nitrogen is added after 10~20 minutes of nitrogen entering. After three repeated operations, when the pointer of the pressure gauge of the reactor does not swing when you knock on it with your hand, open the vent valve, turn the nitrogen pressure reducing valve gently, and slowly add nitrogen. At this time, the pointer of the pressure gauge of the reactor does not swing significantly, and gas appears in the vent valve and exhaust valve, and different sounds are produced with the size of nitrogen intake, indicating that the reactor is connected to the outside world, close the nitrogen pressure reducing valve and remove the connecting pipeline.

[0126] Open the lid of the reactor, suck out the reaction materials with a pipette, rinse the remaining materials and catalyst in the reactor with bottle washing water, collect them in a beaker, and suck away the reaction liquid with a pipette, then cover the catalyst with the water used to rinse the reactor and leave it for next use or recovery and activation.

[0127] Combine the reaction solution and the previous flushing water in the reactor, and after the reduction reaction is completed, collect the solution for the next step. The liquid chromatography test result is greater than 98.5% (total active ingredients).

[0128] Reduction reaction 22 Dissolve the products of the previous step sulfonation reaction 13 and sulfonation reaction 18 in a certain amount of water, and adjust the pH to 9 with sodium carbonate. Slowly add sodium borohydride at 40~90℃, add sodium borohydride evenly, add according to the solution dissolution, not too fast. Take samples at any time during the reaction to understand the reaction situation. You can also use the ethanol solution of 2,4-dinitrophenylhydrazine hydrochloride to observe the reaction solution and its color (yellow crescent) by spotting on filter paper. If you can't see the color at the junction of the spotting infiltration circle, it means that the reaction is going smoothly and has reached the reaction reduction end point. At this time, add an appropriate amount of sodium borohydride, keep warm for 4~8 hours, add sodium chloride equivalent to 10~30% of the mass of the sulfonate for salting out, stir for 2~5 hours and cool naturally to room temperature, filter, drain, and then wash 3~5 times with a sodium chloride aqueous solution with a density of 1.15, then drain and press dry, take out the filter cake, and detect the solid content of 60~70%. The content is greater than or equal to 98.5% (total active ingredients), and the yield is greater than 88%. Go to the next stage.

[0129] Reduction reaction 23 Take the filter cakes from sulfonation experiments 13 and 18 and dissolve them in a certain amount of water. Adjust the pH to 9 with sodium carbonate, and then heat and concentrate. When the solid is precipitated, slowly cool down until the solid is completely precipitated and filter. Dry the filter cake at 120-160°C to constant weight, and then crush it. Crush and bake at 140-160°C for one hour, and add it to a dry reactor after cooling slightly. Add half of its capacity of isopropanol to the reactor in advance and stir it. Slowly add aluminum isopropoxide at 50-85°C while stirring. The detection method is the same as the above preparation example. If aluminum isopropoxide has obvious whitening and white powder on the surface due to moisture absorption, increase the dosage appropriately. The action should be accurate during sampling and testing, and pay attention to the condensation and clogging of the sampling tube due to temperature drop. After the reaction is completed, transfer the reaction material to a four-times-large reaction bottle. Prepare water three times the volume of the reaction material in advance. After adding, stir and heat to evaporate isopropanol. When the material temperature reaches 90°C, the isopropanol is basically evaporated. If the material is viscous during this process, it can be diluted with water. Then stir for 2 to 5 hours and cool naturally to room temperature. Filter to remove aluminum hydroxide precipitate, wash three times with pure water, merge into the mother liquor, and heat and concentrate in a distillation bottle until the distillate reaches three-quarters of the volume of the concentrate (during this period, it is necessary to change to a small-volume concentration bottle). The concentrate is tested by liquid chromatography, and the main peak content is greater than 98.5% (total effective ingredients).

[0130] Reduction reaction 24 Take the filter cakes of sulfonation experiment 13 and sulfonation experiment 18 and dissolve them in a certain amount of water, adjust pH to 9 with sodium carbonate, slowly add sodium chloride solid powder while stirring until the amount of sodium chloride reaches 10%~20% of the amount of water used in this liquid, then add and stir for 2~6 hours until precipitation is complete and filter, take the filter cake when it is dried in an oven at 120~160℃ and weigh constantly, then repeat the above preparation example. The reaction solution is tested by liquid chromatography, and the content is greater than 98.5% (total effective ingredients).

[0131] Table 5 Reduction reaction data

[0132] (4) Dehydration reaction Dehydration reaction 25 Take the reduction solution of the reduction reaction 21 with the catalyst removed and concentrate until solid precipitation occurs, and slowly add it from the funnel to 50% sulfuric acid, the temperature of which is controlled at 50-100°C. After adding, rinse the funnel and the materials adhering to the container, keep the temperature at 50-100°C for 5-8 hours, and take samples to detect whether the conversion is complete and the reaction is over.

[0133] Dehydration reaction 26 Slightly heat the reaction solution of reduction experiment 22, add 5-20% solid sodium chloride crystals equivalent to the weight of the solution under stirring, filter, drain and compact. Then wash with saturated sodium sulfate to remove chloride ions as much as possible, then compact and drain again, and put the drained filter cake into sulfuric acid solution for dehydration as in dehydration experiment 25, and enter the next stage of post-processing and refining after dehydration.

[0134] Dehydration reaction 27 Distill the reaction liquid of reduction reaction 23 to recover isopropanol until about half of it is evaporated. When the temperature drops to room temperature, slowly add water, the amount of water is slightly more than the recovered isopropanol, raise the temperature, and continue to add isopropanol to evaporate. When 90°C, the isopropanol is completely evaporated, and the temperature is slightly lowered and water is added until the material is no longer viscous. Cool and filter to remove insoluble aluminum hydroxide. Heat the filtrate and concentrate until solids precipitate, then stop heating. After concentrating and cooling slightly, operate according to dehydration reaction 25. The experimental operation is completed and the next refining step is entered.

[0135] Dehydration reaction 28 The operation is exactly the same as the reduction reaction 24 and the dehydration reaction 27. The difference is that the post-treatment method of the reduction product is different. After the operation is completed, the reaction material is retained and enters the next refining stage.

[0136] Dehydration reaction 29 Add sulfuric acid of different concentrations of sulfonation reactions 14-17 into a stainless steel reactor at a height no higher than half of the reactor body, add platinum carbon, and cover the reactor tightly. The hydrogen reduction process is the same as that of reduction reaction 21. The difference is that since the system medium is strongly acidic, dehydration occurs as soon as the reduction reaction occurs.

[0137] After the reaction is completed, the reaction solution is taken out as in the reduction reaction, the catalyst is separated, the reaction solution is slightly heated to 50~80℃, activated carbon is added, stirred to cool down, the filtrate is filtered, and the temperature is slightly raised again, and sodium chloride equivalent to 5~20% of the solution is added for salting out. After adding sodium chloride, stir at room temperature for 2~6 hours and filter, and wash the solid material in the funnel with a saturated sodium chloride aqueous solution. When the pH of the washing water is below 5, compact and drain, take out the filter cake and dissolve it in a certain amount of water, adjust the pH to 10~11 with sodium carbonate, and then salt out with sodium chloride equivalent to 10~20% of the solution weight, add sodium chloride and stir for 2~6 hours, filter, drain, compact, and dry to obtain the finished mixed fluorescent whitening agent. Its yield (starting from biphenyl) is greater than 70%, and the average yield of each step of the reaction is greater than 90%, and the content and total isomers are greater than 98.6%. The sample results are equivalent to the commercially available fluorescent whitening agent CBS. The residue in water is slightly lower than CBS.

[0138] Dehydration reaction 30 Take sulfonation reaction 18 and operate under the same conditions as dehydration reaction 29. The yield is greater than 70% based on biphenyl, and the reduction dehydration yield is greater than 90%. The content is greater than 98.6% (total isomers), and the result of the cloth sample is equivalent to that of the fluorescent brightener CBS. The bottom water residue of the dyed sample is slightly less than that of CBS.

[0139] Dehydration reaction 31 Take the reaction liquid of sulfonation reaction 19 and repeat the operation of dehydration reaction 29. The final result is equivalent to dehydration reaction 29 and dehydration reaction 30. Yield: greater than 70% based on biphenyl, and reduction dehydration yield greater than 90%. Content greater than 98.6% (total isomers) Dehydration reaction 32 Different concentrations of reactant solutions of cyclization reaction 20 were taken, catalyzed by platinum carbon, and carried out according to the method and conditions of dehydration reaction 29. The results are as follows. The results of the cloth samples are similar, and the intensity is close to that of the fluorescent brightener CBS. The bottom water residue of the dyed sample is slightly lower than that of the fluorescent brightener CBS.

[0140] Table 6 Dehydration reaction partial data

[0141] (5) Sulfonic acid salt formation reaction Salt formation reaction 33 Take the dehydration reaction 25 material and stir it, add 10~20% of sodium chloride equivalent to the weight of the solution, stir for 2~4 hours after adding, the material is completely precipitated, filter, drain and compact. Take out the material in the funnel, dissolve it with a certain amount of water, adjust the pH to 11 with sodium carbonate, add activated carbon and stir for 1~3 hours to filter out the activated carbon, add 10~20% of sodium chloride solid equivalent to the weight of the solution to the filtrate to promote the precipitation of the product, stir for 2~6 hours after adding, filter and compact, drain, and then wash it 3 times with a sodium chloride solution with a density of 1.15, drain and press, take out the material in the funnel and dry it. The test results are equivalent to those of the dehydration reaction 29.

[0142] Salt formation reaction 34~36 The solutions of dehydration reactions 26~28 were taken separately and the post-treatment 33 method and conditions were repeated. The final results were similar to those of dehydration 29.

[0143] Table 7 Salt formation reaction data

[0144] (6) Effect Example Performance test with reference to national standards: The production process of this application, through a series of reactions and operations such as acylation, sulfonation, reduction, dehydration, and salt formation of biphenyl, finally obtains the sulfonated products of benzene rings at different positions of 4,4'-distyrylbiphenyl. This structure, similar to the diffusant NNO, has good water solubility and is suitable for use in detergents, etc. The performance and application of the product are tested in accordance with the national standard (industry) HG / T37 / 26 fluorescent brightener CF351 (i.e., fluorescent brightener CBS in this application).

[0145] Table 8 is extracted from the quality requirements of HG / T37 / 26 fluorescent brightener CF351

[0146] Note 1: Due to commercial needs, different manufacturers of commercial fluorescent brightener CBS (fluorescent brightener 351) have their own modified additives, which will affect the test results; there are further annotations in the subsequent application tests. Therefore, the commercial fluorescent brightener CBS is used. The non-commercial fluorescent brightener 351 is taken from the production enterprise before commercialization (before addition), and is taken from its filter press position.

[0147] The standard does not specify the odor detection instruments and standards. This application uses targeted detection instruments such as nitrogen oxides, sulfur oxides, organic amines, organic aromatic compounds, etc. for detection, but no specific data was tested.

[0148] Table 9 Test results of non-commercial fluorescent brightener CF351 (Note 1)

[0149] Note 2: From the results of Table 8 and Table 9, it can be found that except for two indicators that were not measured and the water content, the other indicators are basically the same. The fluorescent whitening agent of the product is granulated by spraying, and its size is uniform and in the form of microspheres; the process of this application is simply ground into powder.

[0150] Note 3: As for the water content, because the glass plate is installed in the oven, the amount is small and it is easy to dry, so the water content is lower than that of the commodity. This is the difference between large-scale production and laboratory scale.

[0151] Table 10 Test results of the products obtained in this application

[0152] Note 1: Since the raw materials, intermediates and chemical reagents used in this application process do not contain harmful aromatic amines, this test was not performed.

[0153] Note 2: Only the catalyst metals nickel and palladium, and the reducing agents aluminum, boron and their compounds were tested. From the data in Table 10 and Table 8, it can be found that the two have only a slight difference in wavelength, which can even be regarded as within the error range (understood as consistent), but after multiple tests, changing the instruments of different units, the result is the same (350±1). Therefore, the product obtained by the process of this application is slightly different from the fluorescent whitening agent CBS.

[0154] Regarding the detection of compounds, this application also conducted a variety of tests on raw materials, intermediates, and final products. For example, for the final product, i.e., mixed fluorescent brightener, a UV light test was conducted (compared with commercial fluorescent brightener CBS); a transmittance comparison test, UV absorption, sulfate, chloride ion, ash content, free acid, free base, solubility and dissolution rate, etc. The data were not included only as process optimization and improvement.

[0155] Effect Example: Application Test As a detergent additive, the most basic application indicator of fluorescent whitening agents is to increase the whiteness (brightness) of fabrics. The fluorescent whitening agent synthesized in this application is used for comparative testing with the semi-finished product of fluorescent whitening agent CBS before commercialization (because the commercial fluorescent whitening agent CBS generally needs to add blue-toned dyes to achieve the blue-shift effect, which is also explained in the notes of Table 9). In this way, the test process will not be affected by additives (the dyes added by different manufacturers are also different).

[0156] Test method: Take 0.5g (analytical balance, accurate to 0.001, the same below) of the fluorescent whitening agent sample of this application (salt-forming reaction 33) and the conventional fluorescent whitening agent CBS sample in the field, respectively, dissolve them in 500ml volumetric flasks and add water (tap water, the same below) to the scale and shake well and mark the number to prevent confusion. Take several pieces of 1g and 0.05g cotton cloth samples (long strips). Several 500ml beakers and several glass rods. The dyeing time is 12%, 15 minutes, because the first wash (adding laundry detergent) of the washing machine is generally this time.

[0157] Staining test experiment 1: Number three beakers 1, 2, and 3. Add 225 ml of water to beaker 1 (for blank comparison), 200 ml of water to beaker 2, and 200 ml of water to beaker 3. Then use a pipette to take 25 ml from the fluorescent brightener CBS volumetric flask and place it in beaker 2 and stir it with a glass rod; take 25 ml from the fluorescent brightener volumetric flask of this application and place it in beaker 3 and stir it with a glass rod. Take three cloth samples and place them in three beakers respectively, wet them, and stir them with a glass rod. At the same time, put 0.05 g of cloth sample in beaker 3 and stir it. After 12 minutes, take out the cloth sample (keep the dye solution for standby use), wash it three times with water (rub and squeeze water by hand), squeeze it dry, put it in an oven at 80 degrees to dry, take it out for testing after 20 minutes, and the results are shown in indicators 1, 2, and 3 in Table 11.

[0158] Staining test experiment 2: Place a piece of fabric sample in beaker No. 2 and No. 3 respectively after dyeing in dyeing test experiment 1, take it out after 15 minutes, wash and dry it, and the fabric sample test is shown in indicators 4 and 5 in Table 11 Staining test experiment 3: The operation is the same as that of dyeing test experiment 2: the purpose is to test the residual fluorescent whitening agent in the dye solution. The results of the fabric samples are shown in indicators 6 and 7 in Table 11.

[0159] Staining test experiment 4: Add 10g of anhydrous sodium sulfate to each of the two beakers in dyeing test experiment 3 (sodium sulfate has the function of promoting dyeing, the purpose is to allow the fluorescent whitening agent in the dye solution to be absorbed into the fabric sample as much as possible), stir it to completely dissolve it, and then heat it slightly to make the dye solution temperature in the beaker reach about 80 degrees (±2), and then put a piece of fabric sample in each beaker and stir it. The fabric sample should be marked (cut) in advance. After 15 minutes, take it out, wash it with water, and dry it. The test results are shown in indicators 8 and 9 in Table 11.

[0160] Table 11 Dyeing whiteness test results

[0161] From the data in Table 11 and visual observation, it can be seen that the fluorescent whitening agent of the present application and the fluorescent whitening agent CBS can increase the fabric sample by 5% under the same-year conditions, that is, the coloring rate is high. There is no obvious difference in the comparison of fabric samples of the same quality, except that the data of the instrument test is a little higher. Therefore, the fabric sample quality was increased for the same-year test. The subsequent fabric sample test results also show that the residual fluorescent whitening agent of the present application in the dyeing water is lower than that of the fluorescent whitening agent CBS (351). Therefore, the comprehensive advantages of the present application are not only in the synthesis described in the article, but also in the application aspect. It has more advantages in terms of cost, environment, safety, and friendliness.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for preparing a composite fluorescent whitening agent, characterized in that: The following steps are involved: Step 1: Acylation reaction Using phenylacetyl chloride and biphenyl as raw materials, adding aluminum chloride, an acylation reaction occurs in the absence of solvent or in the presence of a solvent to obtain an acylated product 4,4'-diphenylacetylbiphenyl; Step 2: Sulfonation reaction The acylated product 4,4'-diphenylacetylbiphenyl obtained in step 1 is added to sulfuric acid for sulfonation reaction to obtain a sulfonated product; the sulfonated product comprises a 2,4'-sulfonated product and a 4,4'-sulfonated product; Step 3: Carbonyl reduction The sulfonated product obtained in step 2 is reacted under reducing agent conditions to obtain a reduced product; Step 4: Dehydration reaction The reduced product obtained in step 3 is subjected to a dehydration reaction to obtain a dehydrated product; Step 5: Sulfonic acid salt formation reaction The dehydrated product obtained in step 4 is added to the salt reaction solution and stirred for a certain period of time to obtain the final product.

2. The preparation method according to claim 1, characterized in that: In the step 2, Based on the total mass of the sulfonated product, the mass percentage content of the 2,4'-position sulfonated product is 80% to 90%; The mass percentage content of the 4,4'-position sulfonation product is 5% to 9%; The remainder includes any one or more of a 4,3'-sulfonated product, a 2,3'-sulfonated product, a 2,2'-sulfonated product, and a 3,3'-sulfonated product.

3. The preparation method according to claim 2, characterized in that: Based on the total mass of the sulfonated product, the mass percentage content of the 4,3'-position sulfonated product is less than or equal to 2.5%; and / or; The mass percentage content of the 2,3'-position sulfonation product is less than or equal to 2%; and / or; The mass percentage content of the 2,2'-position sulfonation product is less than or equal to 2.2%; and / or; The mass percentage content of the 3,3'-position sulfonation product is less than or equal to 0.5%.

4. The preparation method according to any one of claims 1 to 3, characterized in that In step 2, the mass percentage concentration of the sulfuric acid is above 90%; and / or; The molar ratio of the acylated product 4,4'-diphenylacetylbiphenyl to sulfuric acid is 1:6-12.

5. The preparation method according to any one of claims 1 to 3, characterized in that The solvent in step 1 includes any one or more of dichloromethane, tetrahydrofuran, cyclohexane, n-hexane, 1,2-dichloroethane, n-cycloheptane, petroleum ether, solvent oil, light oil, sulfonated kerosene or nitrobenzene; and / or; The molar ratio of phenylacetyl chloride to biphenyl is 2.2-2.6:1-2; and / or; The molar ratio of aluminum chloride to biphenyl is 2.2-3.0:1-2; and / or; The mass ratio of the solvent to biphenyl is 2-10:

1.

6. The preparation method according to claim 5, characterized in that: The solvent in step 1 further includes a pretreatment step, which includes adding the solvent into fuming sulfuric acid, stirring it thoroughly and then letting it stand, and taking the upper organic phase as the solvent for the acylation reaction.

7. The preparation method according to claim 1, characterized in that: The reducing agent in step 3 includes any one or more of hydrogen, sodium borohydride, aluminum isopropoxide / isopropanol, platinum carbon / hydrogen, palladium carbon / hydrogen, and nickel / hydrogen.

8. The preparation method according to claim 1, characterized in that: The dehydration reaction in step 4 is carried out in sulfuric acid, and the mass percentage concentration of the sulfuric acid is 40% to 80%.

9. The preparation method according to claim 1, characterized in that: The reduction reaction in step 3 and the dehydration reaction in step 4 are a one-step reaction.

10. The preparation method according to claim 1, characterized in that: In step 5, the mass of the dehydrated product is 10% to 20% of the mass of the salt.

Images