Process for the preparation of butyl gellanate

Abstract

The present application relates to the technical field of perfume preparation, and particularly relates to a preparation method of butyl position decanolide. The present application provides a preparation method of butyl position decanolide, which comprises the following steps: mixing cyclopentanone, n-pentanal and a solvent, then dropping the obtained mixed solution into lye to perform a hydroxy aldehyde condensation reaction to obtain 2-pentylidene cyclopentanone; under the action of a catalyst, the 2-pentylidene cyclopentanone is subjected to a hydrogen reduction reaction with hydrogen to obtain 2-pentyl cyclopentanone; with selenium dioxide as a catalyst, the 2-pentyl cyclopentanone and an oxidant are subjected to a Baeyer-villiger oxidation reaction in a reaction solvent to obtain the butyl position decanolide. The preparation method has a short synthesis route, is easy to realize industrial production, and has a high yield.

Description

Technical Field

[0001] This invention relates to the field of fragrance preparation technology, and more particularly to a method for preparing butylated decanoic acid lactone. Background Technology

[0002] 5-hydroxydecanoic acid lactone, also known as butylated decanoic acid lactone, is an edible flavoring permitted for use under GB 2760-96. It is characterized by a strong and lasting buttery aroma and is the main flavoring agent for milk and cream flavorings. It is also widely used in blending flavorings such as coconut, plum, and peach. 5-hydroxydecanoic acid lactone is widely used in margarine, soft drinks, ice cream, candy, condiments, and baked goods, and there is a large market demand for it.

[0003] Regarding the synthesis methods of butyl decanoate, there are three main methods reported in domestic and foreign literature: 1) First, prepare hydroxydecanoic acid, then dehydrate and cyclize it to the corresponding decanoate; 2) Starting from adipic acid, synthesize decanoate through five steps of reaction including esterification, condensation, hydroxylation, hydrolysis decarboxylation and Baeyer-Villiger oxidation; 3) Use n-pentanal and cyclopentanone as starting materials to synthesize decanoate through unit reactions such as condensation, dehydration, reduction and oxidation. Among the above three synthesis methods, the starting materials of methods 1) and 2) are difficult to obtain, making it impossible to produce in series, or the reaction route is too long, resulting in low overall yield and making it difficult to achieve industrial production; the synthesis route of method 3) is short and relatively easy to achieve industrial production, but the yield is low. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing butylated decanoate, wherein the preparation method has a short synthetic route, is easy to implement for industrial production, and has a high yield.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing butylated decanoic acid lactone, comprising the following steps: Cyclopentanone, n-pentanal, and a solvent were mixed, and the resulting mixture was added dropwise to an aldol condensation reaction to obtain 2-pentylcyclopentanone. Under the action of a catalyst, the 2-pentylcyclopentanone was subjected to a hydrogenation reduction reaction with hydrogen to obtain 2-pentylcyclopentanone. Using selenium dioxide as a catalyst, the 2-pentylcyclopentanone and the oxidant undergo a Baeyer-villiger oxidation reaction in a reaction solvent to obtain the butyldecyl lactone.

[0006] Preferably, the molar ratio of n-pentanal, cyclopentanone, and alkali in the alkaline solution is 1:(1.1~2.5):(0.01~1). The alkali in the alkaline solution is one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, potassium carbonate, sodium carbonate, and sodium hydride.

[0007] Preferably, the mixing temperature is 10~40℃; The dripping time is 10-60 minutes, and the dripping is followed by heat preservation for 0.5-2 hours.

[0008] Preferably, the aldol condensation reaction is carried out at a temperature of 60-100°C for 2-8 hours.

[0009] Preferably, after the aldol condensation reaction is completed, the process further includes allowing the layers to stand and separate into an aqueous layer and an oil layer, and then sequentially acidifying the oil layer to neutral, desolventizing, and distilling it. The acid used in the acidification is acetic acid, the desolvation temperature is 70~85℃, and the distillation yields a fraction at 92℃.

[0010] Preferably, the catalyst is a Pd / C catalyst, wherein the mass percentage of Pd in ​​the Pd / C catalyst is 1-10%; The mass ratio of 2-pentylcyclopentanone to Pd in ​​the Pd / C catalyst is 1:(0.01~0.05).

[0011] Preferably, the hydrogenation reduction reaction is carried out at a temperature of 30~90℃, a pressure of 0.2~2.0MPa, and a time of 4~6h.

[0012] Preferably, the oxidant is hydrogen peroxide, and the mass concentration of the hydrogen peroxide is 30% to 50%. The molar ratio of the active substance in the 2-pentylcyclopentanone and the oxidant is 1:(1.0~2.0). The mass ratio of 2-pentylcyclopentanone to selenium dioxide is 1:(0.002~0.05).

[0013] Preferably, the Baeyer-villiger oxidation reaction is carried out at a temperature of 20-90°C for 2-8 hours.

[0014] Preferably, after the Baeyer-villiger oxidation reaction is completed, the process further includes standing, followed by washing, solvent removal and distillation of the resulting oil layer in sequence; The detergent used for washing is a 10% sodium sulfite solution; The distillation pressure is 110~230Pa and the temperature is 140~220℃.

[0015] This invention provides a method for preparing 2-decyl lactone, comprising the following steps: mixing cyclopentanone, n-pentanal, and a solvent, then adding the resulting mixture dropwise to an alkaline solution to perform an aldol condensation reaction to obtain 2-pentylcyclopentanone; under the action of a catalyst, reacting the 2-pentylcyclopentanone with hydrogen to undergo a hydrogenation reduction reaction to obtain 2-pentylcyclopentanone; and using selenium dioxide as a catalyst, reacting the 2-pentylcyclopentanone with an oxidant in a reaction solvent to undergo a Baeyer-Villiger oxidation reaction to obtain the 2-decyl lactone. Since pentanal and cyclopentanone undergo a self-condensation reaction under alkaline conditions, the preparation method of this invention avoids this self-condensation reaction by changing the mixing method of cyclopentanone, pentanal, and sodium hydroxide. Cyclopentanone and pentanal are mixed and then added dropwise to the alkaline solution, thereby increasing the yield of the aldol condensation reaction to over 95%. Simultaneously, the preparation method of this invention introduces a selenium dioxide catalyst, increasing the yield of the Baeyer-villiger oxidation reaction to over 95%. Since the selenium dioxide catalyst can act as an electrophilic reagent to attack the oxygen of the ketone carbonyl group, forming a stable selenic acid intermediate, it readily accepts nucleophilic attack from hydrogen peroxide, thus improving the reaction rate and yield. Detailed Implementation

[0016] This invention provides a method for preparing butylated decanoic acid lactone, comprising the following steps: Cyclopentanone, n-pentanal, and a solvent were mixed, and the resulting mixture was added dropwise to an aldol condensation reaction to obtain 2-pentylcyclopentanone. Under the action of a catalyst, the 2-pentylcyclopentanone was subjected to a hydrogenation reduction reaction with hydrogen to obtain 2-pentylcyclopentanone. Using selenium dioxide as a catalyst, the 2-pentylcyclopentanone and the oxidant undergo a Baeyer-villiger oxidation reaction in a reaction solvent to obtain the butyldecyl lactone.

[0017] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0018] The preparation method described in this invention is shown in Formula 1: Formula 1.

[0019] In this invention, cyclopentanone, n-pentanal, and a solvent are mixed, and the resulting mixture is added dropwise to an alkaline solution to carry out an aldol condensation reaction, yielding 2-pentylcyclopentanone.

[0020] In this invention, the solvent is preferably one or more of toluene, dichloromethane, dichloropropane, ethyl acetate, cyclohexane, and dichloroethane, more preferably toluene, dichloromethane, or cyclohexane. When the solvent is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In the embodiments of this invention, the solvent can be toluene.

[0021] In this invention, the concentration of the alkaline solution is preferably 0.1-2%, more preferably 0.1%, 0.3%, 0.5%, 0.8%, 1.0%, 1.3%, 1.5%, 1.8%, or 2%. In an embodiment of this invention, the concentration of the alkaline solution can be 0.85%.

[0022] In this invention, the alkali in the alkaline solution is preferably one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, potassium carbonate, sodium carbonate, and sodium hydride, more preferably sodium hydroxide, potassium hydroxide, or potassium carbonate. When the alkali in the alkaline solution is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In an embodiment of this invention, the alkali in the alkaline solution can be sodium hydroxide.

[0023] In this invention, the molar ratio of n-pentanal, cyclopentanone, and alkali in the alkaline solution is preferably 1:(1.1~2.5):(0.01~1), more preferably 1:1.1:0.6, 1:1.1:0.8, 1:1.1:1.0, 1:1.1:0.4, 1:1.5:0.01, 1:1.5:0.02, 1:1.5:0.05, 1:1.5:0.1, 1:1.5:0.2, 1:1.5:0.4, 1:1.5:0.6, or 1:1.5:0. 8. 1:1.5:1, 1:2:0.01, 1:2:0.02, 1:2:0.05, 1:2:0.1, 1:2:0.2, 1:2:0.4, 1:2:0.6, 1:2:0.8, 1:2:1, 1:2.5:0.01, 1:2.5:0.02, 1:2.5:0.05, 1:2.5:0.1, 1:2.5:0.2, 1:2.5:0.4, 1:2.5:0.6, 1:2.5:0.8 or 1:2.5:1. In embodiments of the present invention, the molar ratio of n-pentanal, cyclopentanone and alkali in the alkaline solution can be 1:1.67:0.04, 1:1.1:0.6, 1:1.1:0.8, 1:1.1:1.0 or 1:1.1:0.4.

[0024] In this invention, the mass ratio of n-pentanal to solvent is preferably 1:(1.5~3.5), more preferably 1:1.5, 1:1.8, 1:2.0, 1:2.2, 1:2.5, 1:2.7, 1:3.0, 1:3.3 or 1:3.5. In an embodiment of this invention, the mass ratio of n-pentanal to solvent can be 1:2.5.

[0025] In this invention, the mixing is preferably carried out under stirring conditions; the mixing temperature is preferably 10~40℃, more preferably 10℃, 15℃, 20℃, 25℃, 30℃, 35℃ or 40℃; the mixing time is preferably 1~5h, more preferably 1h, 2h, 3h, 4h or 5h. In an embodiment of this invention, the mixing temperature can be 20℃ and the mixing time can be 0.5h.

[0026] In this invention, the dripping is preferably carried out under stirring conditions, and the dripping time is preferably 10-60 min, more preferably 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min. In an embodiment of this invention, the dripping time can be 30 min.

[0027] After the addition is completed, the present invention preferably includes heat preservation, the heat preservation temperature being preferably the temperature at which the mixture was prepared; the heat preservation time is preferably 0.5 to 2 hours, more preferably 0.5 hours, 1 hour, 1.5 hours, or 2 hours. In an embodiment of the present invention, the heat preservation time can be 2 hours.

[0028] In this invention, the temperature of the aldol condensation reaction is preferably 60~100℃, more preferably 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃; the time is preferably 2~8h, more preferably 2h, 3h, 4h, 5h, 6h, 7h or 8h. In embodiments of this invention, the temperature of the aldol condensation reaction can be 87℃ or 77℃, and the time can be 3h or 2h.

[0029] In this invention, controlling the conditions of the aldol condensation reaction within the above-mentioned range can ensure that the content of n-pentanal in the product system obtained by the aldol condensation reaction is ≤1%.

[0030] After the aldol condensation reaction is completed, the present invention preferably includes allowing the layers to stand and separate into an aqueous layer and an oil layer, and then sequentially acidifying the oil layer to neutral, desolventizing, and distilling it.

[0031] In this invention, the settling time is preferably 0.1 to 3 hours, more preferably 0.1 hours, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours. In an embodiment of this invention, the settling time can be 0.5 hours.

[0032] In this invention, the acid used for acidification is preferably acetic acid. This invention does not impose any special limitations on the amount of acetic acid used; any amount known to those skilled in the art can be used to acidify to neutrality. After acidification, this invention also preferably includes layering; this invention does not impose any special limitations on the layering process; any process known to those skilled in the art can be used.

[0033] In this invention, the solvent removal temperature is preferably 70~85℃, more preferably 70℃, 75℃, 80℃ or 85℃. In an embodiment of this invention, the solvent removal temperature can be 80℃. In this invention, the solvent removal is preferably provided with a vacuum by a circulating water pump, and the vacuum is preferably -0.95MPa.

[0034] In this invention, the solution obtained after desolventizing is a mixture of 2-amylcyclopentanone and toluene.

[0035] In this invention, the distillation preferably yields a fraction at 92°C. Furthermore, the distillation is preferably performed using an oil pump, with the distillation temperature preferably at 100°C and the pressure preferably at 200 Pa.

[0036] In this invention, the content of 2-amylcyclopentanone is preferably ≥95%.

[0037] After obtaining the 2-pentylcyclopentanone, the present invention, under the action of a catalyst, reacts the 2-pentylcyclopentanone with hydrogen in a hydrogenation reduction reaction to obtain 2-pentylcyclopentanone.

[0038] In this invention, the catalyst is preferably a Pd / C catalyst, and the mass percentage of Pd in ​​the Pd / C catalyst is preferably 1-10%, more preferably 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. In an embodiment of this invention, the mass percentage of Pd in ​​the Pd / C catalyst can be 3%.

[0039] In this invention, the mass ratio of 2-pentylcyclopentanone to Pd in ​​the Pd / C catalyst is preferably 1:(0.01~0.05), more preferably 1:0.01, 1:0.02, 1:0.03, 1:0.04 or 1:0.05. In an embodiment of this invention, the mass ratio of 2-pentylcyclopentanone to Pd in ​​the Pd / C catalyst can be 1:0.02.

[0040] Before carrying out the hydrogenation reduction reaction, the present invention preferably includes sequentially purging with low-pressure nitrogen and then with low-pressure hydrogen; the pressure of the low-pressure nitrogen is preferably 0.2~0.3 MPa, and the number of purgings is preferably 3. In the present invention, after purging with low-pressure nitrogen, it is further preferred to maintain the pressure at 0.6 MPa for 30 minutes, check the airtightness with soapy water, and slowly discharge the nitrogen after there is no pressure drop. In the present invention, the pressure of the low-pressure hydrogen is preferably 0.2~0.3 MPa, and the number of purgings is preferably 3. In the present invention, after purging with low-pressure hydrogen, it is further preferred to check the airtightness with soapy water, and slowly discharge the hydrogen after there is no pressure drop.

[0041] In this invention, the temperature of the hydrogenation reduction reaction is preferably 30~90℃, more preferably 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ or 90℃; the pressure is preferably 0.2~2.0MPa, more preferably 0.2MPa, 0.4MPa, 0.6MPa, 0.8MPa, 1.0MPa, 1.2MPa, 1.4MPa, 1.6MPa, 1.8MPa or 2.0MPa; the time is preferably 4~6h, more preferably 4h, 4.5h, 5h, 5.5h or 6.0h. In an embodiment of this invention, the temperature of the hydrogenation reduction reaction can be 40℃, the pressure can be 1.0MPa, and the time is until no more hydrogen is absorbed (time is 5h).

[0042] In this invention, the preferred standard for determining the completion of the hydrogenation reduction reaction is that after the hydrogen is no longer absorbed and there is no pressure drop, GC sampling analysis is performed, with GNB ≤ 1.0% and GND (isomeric) ≤ 1.0%.

[0043] In this invention, controlling the conditions and parameters of the hydrogenation reduction reaction within the above-mentioned range can ensure that the content of 2-pentylcyclopentanone in the obtained product system is ≤0.5%.

[0044] After the hydrogenation reduction reaction is completed, the present invention preferably includes sequential cooling, filtration and filtrate desolvation; the present invention does not have any special limitations on the cooling, filtration and filtrate desolvation process, and any process known to those skilled in the art can be used.

[0045] In this invention, the filter cake obtained by filtration can be directly reused in the next batch (i.e., the next experiment).

[0046] In this invention, the content of 2-pentylcyclopentanone obtained after desolventizing the filtrate is preferably ≥95%.

[0047] After obtaining the 2-pentylcyclopentanone, the present invention uses selenium dioxide as a catalyst to carry out the Baeyer-villiger oxidation reaction of the 2-pentylcyclopentanone and the oxidant in a reaction solvent to obtain the butyl-decyl lactone.

[0048] In this invention, the oxidant is preferably hydrogen peroxide, and the mass concentration of the hydrogen peroxide is preferably 20-50%, more preferably 20%, 30%, 40% or 50%. In an embodiment of this invention, the mass concentration of the hydrogen peroxide can be 50%.

[0049] In this invention, the reaction solvent is preferably one of formic acid, dichloromethane, toluene, cyclohexane, acetic acid, and propionic acid. In an embodiment of this invention, the reaction solvent may be acetic acid.

[0050] In this invention, the molar ratio of the 2-pentylcyclopentanone to the active substance in the oxidant is preferably 1:(1.0~2.0), more preferably 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8 or 1:2.0. In an embodiment of this invention, the molar ratio of the 2-pentylcyclopentanone to the active substance in the oxidant can be 1:1.5.

[0051] In this invention, the mass ratio of 2-pentylcyclopentanone to selenium dioxide is preferably 1:(0.002~0.05), more preferably 1:0.002, 1:0.005, 1:0.01, 1:0.02, 1:0.03, 1:0.04 or 1:0.05. In an embodiment of this invention, the mass ratio of 2-pentylcyclopentanone to selenium dioxide can be 1:0.01.

[0052] In this invention, the mass ratio of 2-pentylcyclopentanone to the reaction solvent is preferably 1:(1~3), more preferably 1:1, 1:1.5, 1:2, 1:2.5 or 1:3.0. In an embodiment of this invention, the mass ratio of 2-pentylcyclopentanone to the reaction solvent can be 1:2.

[0053] In this invention, the preferred method for the Baeyer-villiger oxidation reaction of 2-pentylcyclopentanone and the oxidant in a reaction solvent using selenium dioxide as a catalyst is to mix 2-pentylcyclopentanone, the catalyst and the reaction solvent, and then add the oxidant dropwise.

[0054] In this invention, the temperature at which the oxidant is added is preferably 25-50°C, more preferably 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C; the time for adding the oxidant is preferably 2-4 hours, more preferably 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours. In an embodiment of this invention, the temperature at which the oxidant is added can be 25°C, and the time can be 3 hours.

[0055] In this invention, the preferred temperature for the Baeyer-villiger oxidation reaction is 20-90°C, more preferably 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C; the preferred time is 2-8 hours, more preferably 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours. In an embodiment of this invention, the temperature for the Baeyer-villiger oxidation reaction can be 25°C, and the time can be 5 hours.

[0056] In this invention, the standard for judging the Baeyer-villiger oxidation reaction is to perform GC sampling and tracking (take 3-5 drops of the reaction solution into water, add 1.5 mL of ethyl acetate for extraction, and take the supernatant) analysis. When the raw material GNC ≤ 1.0%, the reaction is stopped.

[0057] In this invention, controlling the conditions of the Baeyer-villiger oxidation reaction within the above-mentioned range can ensure that the content of 2-pentylcyclopentanone in the obtained product system is ≤1.0%.

[0058] After the Baeyer-villiger oxidation reaction is completed, the present invention preferably includes a settling period, followed by sequential washing, solvent removal, and distillation of the resulting oil layer. Before the settling period, the present invention preferably includes pouring the product system obtained from the Baeyer-villiger oxidation reaction into water and stirring until homogeneous. The present invention does not impose any special limitations on the settling process; any process well-known to those skilled in the art can be used. The aqueous layer obtained after settling is preferably extracted three times with toluene and then combined with the oil layer. In the present invention, the washing agent is preferably a 10% sodium sulfite solution; the number of washings is preferably three. The present invention does not impose any special limitations on the solvent removal process; any process well-known to those skilled in the art can be used. In the present invention, the distillation pressure is preferably 110~230 Pa, more preferably 110 Pa, 140 Pa, 170 Pa, 200 Pa, 220 Pa, or 230 Pa; the temperature is preferably 140~220℃, more preferably 140℃, 160℃, 180℃, 200℃, or 220℃.

[0059] In this invention, the content of the butylated decanoic acid lactone is preferably ≥98.0%.

[0060] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0061] Example 1 640.0 g of sodium hydroxide solution (mass concentration 0.85%, molar amount of sodium hydroxide 0.136 mol, 0.04 eq) was added to the reactor, and stirring was started. In another reaction flask, 300 g of n-pentanal (3.40 mol, 1 eq), 491.00 g of cyclopentanone (5.78 mol, 1.67 eq) and 750 g of toluene were added and stirred at 20 °C for 0.5 h to prepare a mixed solution. The mixed solution was then added dropwise to the sodium hydroxide solution (dropping time 30 min). After n), keep warm for 2 hours, raise the temperature to 87℃, keep warm for 3 hours (at this time, the content of n-pentanal is ≤1%), let stand for 0.5 hours to separate the layers, separate the water layer, add acetic acid to the oil layer to acidify until the oil layer is neutral, separate the layers to obtain the oil layer, remove the solvent from the obtained oil layer under reduced pressure at 80℃ with a vacuum degree of -0.95MPa, and obtain crude 2-pentylcyclopentanone. Then, use an oil pump to perform reduced pressure distillation (100℃, pressure of 200Pa) to obtain 527.28g of 2-pentylcyclopentanone product (content is 96.0%, yield is 96.8%). In a 1000 mL autoclave, 250 g of 2-pentylcyclopentanone (1.56 mol, 1 eq), 4.75 g of Pd / C catalyst (Pd mass percentage 3%, relative to 2-pentylcyclopentanone mass ratio 0.19%), and 400 mL of methanol were added sequentially. The mixture was stirred until homogeneous. After purging with low-pressure nitrogen three times (0.2–0.3 MPa), the pressure was maintained at 0.6 MPa for 30 min. The airtightness was checked with soapy water. Once no pressure drop was observed, the mixture was slowly discharged. Nitrogen gas was introduced, and low-pressure hydrogen gas was introduced three times (0.2~0.3 MPa) to purge the gas. After checking the airtightness and confirming no pressure drop, the hydrogen gas was discharged. The temperature was raised to 40℃, and 1.0 MPa hydrogen gas was introduced to participate in the reaction for 5 hours. After the hydrogen gas was no longer absorbed and there was no pressure drop, GC samples were taken for analysis. After controlling GNB ≤ 1.0% and GND (isomer) ≤ 1.0%, the temperature was lowered to room temperature, the hydrogen gas was discharged, and low-pressure nitrogen gas was introduced three times. The mixture was filtered and concentrated to obtain a colorless and transparent liquid (247.8 g, normalized content 96.1%, yield 99.0%). Add 150g of 2-pentylcyclopentanone (0.935mol, 1eq), 1.5g of selenium oxide (m / m:1%), and 300g of acetic acid to a reaction flask and stir until homogeneous. Heat to 25℃, and at this temperature, slowly add 95.37g of hydrogen peroxide (1.40mol, wt:50%, 1.5eq) dropwise over 3 hours. After the addition is complete, maintain the reaction temperature for 5 hours. Perform GC sampling (add 3-5 drops of the reaction solution to water, extract with 1.5mL of ethyl acetate, and collect the supernatant) for analysis. Stop the reaction when the raw material GNC ≤ 1.0%. Pour the reaction solution into water, stir until homogeneous, and allow to stand to separate the oil layer and the aqueous layer. Extract the aqueous layer three times with toluene, and combine the oil layers. The oil layer was washed three times with a 10% sodium sulfite solution, the oil layer was separated, and the crude decanolide was concentrated. The crude decanolide was then distilled under reduced pressure at 155℃ and 25Pa to obtain d-decanolide (153.52g, content 98.60%, yield 95.12%).

[0062] Examples 2-5 Referring to Example 1, the differences are shown in Table 1: Table 1. Condition parameters that distinguish Examples 2-5 from Example 1

[0063] Comparative Example 1 272.0 g of sodium hydroxide solution (1% by mass, 0.136 mol of sodium hydroxide, 0.04 eq) was added to a three-necked flask. After heating to 25 °C, 288.28 g of cyclopentanone (3.4 mol, 2 eq) was added dropwise over 2.0 h. After the addition was completed, the color of the reaction system slowly changed from colorless to yellow. Then, at 30 °C, 150 g of n-pentanal (1.70 mol, 1 eq) was slowly added dropwise over about 3 h. The color of the reaction changed from yellow to deep yellow. After the addition was completed, the temperature was maintained at 30 °C and the reaction was stirred for 1 h. After cooling, 36% glacial acetic acid was added. Adjust the pH to 6-7; then allow it to stand and separate into layers, with the upper layer being an organic layer and the lower layer being an inorganic layer. Add toluene to the inorganic layer for extraction, and separate into layers, with the upper layer being a toluene layer and the lower layer being a wastewater layer. Combine the organic and toluene layers and add them to a flask equipped with an oil-water separator. Add oxalic acid, heat and stir until no more water is excreted, cool, and wash with saturated brine and 5% sodium carbonate solution. Distill off the toluene at atmospheric pressure. Use an oil pump to distill under reduced pressure at a temperature of 110℃ and a pressure of -0.1Pa to obtain 251.02g of 2-pentylcyclopentanone (content 87.2%, yield 84.6%).

[0064] Comparative Example 2 50.0 g of 2-pentylcyclopentanone (0.308 mol, 1 eq) was added to a reaction flask and stirred until homogeneous. 122.71 g of peracetic acid (0.338 mol, wt%: 21%, 1.1 eq) was added dropwise over 3 hours at 25°C. After the addition was complete, the reaction was maintained at this temperature for 5 hours. GC sampling was performed (5 drops of the reaction solution were added to water, extracted with 1.5 ml of ethyl acetate, and the supernatant was collected for analysis). The reaction was stopped when the raw material GNC ≤ 1.0%. The reaction solution was poured into water, stirred until homogeneous, and allowed to stand to separate the oil and water layers. The water layer was extracted three times with toluene, and the oil layers were combined. The oil layer was washed three times with 10% sodium sulfite solution, separated, and concentrated to obtain crude decanolide. 37.40 g of d-decanolide product (purity 98.1%, yield 70.0%) was obtained by vacuum distillation at 155°C and 25 Pa.

[0065] Comparative Examples 3-5 The process for preparing butyl decanolide from 2-pentylcyclopentanone in Example 1 is shown in Table 2, with differences in catalyst type, temperature, and time: Table 2. Catalyst types, reaction temperatures, and times for Comparative Examples 3-5

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing butylated decanoic acid lactone, characterized in that, Includes the following steps: Cyclopentanone, n-pentanal, and a solvent were mixed, and the resulting mixture was added dropwise to an aldol condensation reaction to obtain 2-pentylcyclopentanone. Under the action of a catalyst, the 2-pentylcyclopentanone was subjected to a hydrogenation reduction reaction with hydrogen to obtain 2-pentylcyclopentanone. Using selenium dioxide as a catalyst, the 2-pentylcyclopentanone and the oxidant undergo a Baeyer-villiger oxidation reaction in a reaction solvent to obtain the butyldecyl lactone.

2. The preparation method according to claim 1, characterized in that, The molar ratio of n-pentanal, cyclopentanone, and alkali in the alkaline solution is 1:(1.1~2.5):(0.01~1). The alkali in the alkaline solution is one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, potassium carbonate, sodium carbonate, and sodium hydride.

3. The preparation method according to claim 1, characterized in that, The mixing temperature is 10~40℃; The dripping time is 10-60 minutes, and the dripping is followed by heat preservation for 0.5-2 hours.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The aldol condensation reaction is carried out at a temperature of 60-100℃ for 2-8 hours.

5. The preparation method according to claim 4, characterized in that, After the aldol condensation reaction is completed, the process further includes allowing the layers to stand and separate into an aqueous layer and an oil layer, and then sequentially acidifying the oil layer to neutral, desolventizing, and distilling it. The acid used in the acidification is acetic acid, the desolvation temperature is 70~85℃, and the distillation yields a fraction at 92℃.

6. The preparation method according to claim 1, characterized in that, The catalyst is a Pd / C catalyst, wherein the mass percentage of Pd in ​​the Pd / C catalyst is 1-10%; The mass ratio of 2-pentylcyclopentanone to Pd in ​​the Pd / C catalyst is 1:(0.01~0.05).

7. The preparation method according to claim 1 or 6, characterized in that, The hydrogenation reduction reaction is carried out at a temperature of 30~90℃, a pressure of 0.2~2.0MPa, and a time of 4~6h.

8. The preparation method according to claim 1, characterized in that, The oxidant is hydrogen peroxide, and the mass concentration of the hydrogen peroxide is 20%~50%. The molar ratio of the active substance in the 2-pentylcyclopentanone and the oxidant is 1:(1.0~2.0). The mass ratio of 2-pentylcyclopentanone to selenium dioxide is 1:(0.002~0.05).

9. The preparation method according to claim 1 or 8, characterized in that, The Baeyer-villiger oxidation reaction is carried out at a temperature of 20-90°C for 2-8 hours.

10. The preparation method according to claim 9, characterized in that, After the Baeyer-villiger oxidation reaction is completed, the process also includes standing, followed by washing, solvent removal and distillation of the resulting oil layer. The detergent used for washing is a 10% sodium sulfite solution; The distillation pressure is 110~230Pa and the temperature is 140~220℃.

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