A method for preparing tertiary amine using secondary amine as raw material

Abstract

The invention discloses a method for preparing tertiary amines using secondary amines as raw materials. The method comprises the steps of reacting secondary amines as raw materials with acids to generate proton-type ionic liquids, and reacting proton-type ionic liquids and aldehydes under the action of a reducing agent to generate tertiary amines. The secondary amines are fatty secondary amines and / or aromatic secondary amines and / or cyclic secondary amines, the acid is selected from a combination of one or more of organic carboxylic acids and inorganic acids, the aldehyde is a monoaldehyde, a dialdehyde or a polymer of aldehydes, and the reducing agent is selected from a combination of one or more of formic acid, sodium formate, oxalic acid, sodium oxalate and triphenylsilane. The proton-type ionic liquid in the present invention can play a role in self-catalytic reaction, so that while ensuring high yield and high purity of tertiary amine products, mild reaction conditions are achieved, high pressure and hydrogen reduction atmosphere are not required, and safe and green reducing agents can be used.

Description

Technical Field

[0001] The invention relates to a method for preparing tertiary amine by taking secondary amine as raw material. Background Art

[0002] Tertiary amines are widely used in industrial production and life. They can be used as fuel additives, pesticide production, pharmaceutical synthesis, epoxy resin hardeners, intermediates of polyurethane catalysts, raw materials for preparing quaternary ammonium salts / bases, plasticizers, dyes, desulfurizers, etc.

[0003] The conventional synthesis of known tertiary amine products often uses a high-pressure fixed bed reaction device and uses a heterogeneous noble metal catalyst such as Pd or Pt supported on a carrier, and the reaction also needs to be carried out under hydrogen conditions. For example, CN101460445A discloses a method for preparing diisopropylethylamine by amination reaction of diisopropylamine and acetaldehyde using a suspended catalyst Pd / C as a catalyst, and the reaction requires high pressure and hydrogen conditions, and the noble metal catalyst is expensive.

[0004] It is also known that a tertiary amine can be generated by reacting a secondary amine and an aldehyde having more than 2 carbon atoms in the presence of a reducing agent without using a metal catalyst or hydrogen and under normal pressure. For example, Chinese patent CN101360726A discloses a method for preparing a tertiary amine by dropping a secondary amine into a mixed solution of an aldehyde and an acid. The method is characterized in that the aldehyde and formic acid are first mixed, heated to reflux temperature, and then the secondary amine is added to react. The method has requirements for the dropwise addition sequence of the raw materials. When the aldehyde or acid is added dropwise to the other two raw materials, the reaction yield is significantly reduced. After the reaction is completed, a large amount of alkali (such as a NaOH aqueous solution) needs to be added to the reaction system to neutralize the reaction system so that the reaction produces a large amount of waste water containing organic matter.

[0005] It is also known that Chinese patent publication CN102875385A discloses a method of using paraldehyde as a raw material, hydrolyzing it with an acidic catalyst, and then reacting it with diisopropylamine and a reducing agent metal hydride such as sodium borohydride to produce a tertiary amine. The patent does not disclose the purity of the tertiary amine product. At the same time, the reducing agent used, such as sodium borohydride, is highly toxic, easily explosive, and sensitive to water, which is not conducive to the operation of the reaction. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing tertiary amines by reacting an improved proton-type ionic liquid with an aldehyde in view of the shortcomings and deficiencies of the prior art. The method is a homogeneous autocatalytic reaction, does not require high-pressure hydrogen and metal catalyst conditions, and can use a safe and green reducing agent, and the reaction material addition process is safer.

[0007] In order to solve the above technical problems, a technical solution adopted by the present invention is as follows:

[0008] A method for preparing tertiary amine using secondary amine as raw material comprises the steps of reacting the secondary amine as raw material with acid to generate proton type ionic liquid, and reacting the proton type ionic liquid with aldehyde under the action of a reducing agent to generate tertiary amine.

[0009] Furthermore, the carbon number of the secondary amine is less than 30, preferably less than 25, and further preferably less than 20; and / or the secondary amine is an aliphatic secondary amine and / or an aromatic secondary amine; and / or the acid is selected from a combination of one or more of organic carboxylic acids and inorganic acids; and / or the aldehyde is a monoaldehyde, a dialdehyde or a polymer of aldehydes.

[0010] Further, the acid is selected from a combination of one or more of C1-C3 organic carboxylic acids, hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid; preferably, the acid is selected from a combination of one or more of formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, carbonic acid, hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid.

[0011] In some embodiments of the present invention, the reducing agent is selected from a combination of one or more of formic acid, sodium formate, oxalic acid, sodium oxalate and triphenylsilane; preferably, the reducing agent is selected from formic acid, sodium formate, oxalic acid or sodium oxalate.

[0012] The inventors have found that secondary amine and acid can react to generate proton-type ionic liquid under room temperature and normal pressure, the operation is safe and controllable, the molar ratio of secondary amine and acid is close to 1, and the consumption of acid is small. Then the proton-type ionic liquid and aldehyde are reacted to generate tertiary amine under the action of a reducing agent, and the reaction conditions for the reaction of secondary amine and aldehyde to generate tertiary amine are mild, high pressure and hydrogen reducing atmosphere are not required during the reaction, and the reaction yield is high, the purity of the obtained tertiary amine is high, and a safe and green reducing agent is used in the reaction system. The proton-type ionic liquid formed in the reaction system can play a role in catalytic reaction, and the reaction system of the present invention is an autocatalytic reaction system, and no metal catalyst needs to be added.

[0013] In some embodiments of the present invention, the molar ratio of the secondary amine as raw material to the acid is 0.2-1.5, preferably 0.3-1.4, and particularly preferably 0.4-1.2.

[0014] In some embodiments of the present invention, the molar ratio of the aldehyde to the protic ionic liquid is 0.2-5.0, preferably 0.3-3.0, and particularly preferably 0.4-2.0.

[0015] In some embodiments of the present invention, the molar ratio of the reducing agent to the protic ionic liquid is 1.0-5.0, preferably 1.0-2.0.

[0016] In some embodiments of the present invention, the step of using secondary amine as a raw material to react with an acid to generate a protic ionic liquid is carried out at room temperature and normal pressure.

[0017] In some embodiments of the present invention, the step of reacting the protic ionic liquid and the aldehyde under the action of a reducing agent to generate a tertiary amine is carried out at a pressure of 0-5.0 MPa, preferably 0-3.0 MPa, and particularly preferably 0-2.0 MPa.

[0018] In some embodiments of the present invention, the step of reacting the protic ionic liquid and the aldehyde under the action of a reducing agent to generate a tertiary amine is carried out at a temperature of 60-200°C, preferably 120-160°C.

[0019] In some embodiments of the present invention, the reaction time of the protic ionic liquid and the aldehyde under the action of the reducing agent is 5-300 mins, preferably 30-120 mins.

[0020] In some embodiments of the invention, the method comprises the following steps:

[0021] 1) adding the acid dropwise to the secondary amine or adding the secondary amine dropwise to the acid to form the protic ionic liquid;

[0022] 2) adding the proton type ionic liquid and the reducing agent into a reactor, and adding the aldehyde into the reactor;

[0023] 3) introducing nitrogen until the pressure of the reaction system is 0-5.0 MPa, raising the temperature to 60-200° C., and reacting for 5-300 mins;

[0024] 4) After the reaction is completed, the reaction system is purified to obtain the tertiary amine.

[0025] In some embodiments of the present invention, in step 1), the acid is added dropwise to the aqueous solution of the secondary amine to form the protic ionic liquid.

[0026] In some embodiments of the present invention, in step 1), the acid is added dropwise to the secondary amine in the form of an aqueous solution of the acid.

[0027] In some embodiments of the present invention, the aldehyde in step 2) is added to the reactor all at once, intermittently or continuously.

[0028] In some embodiments of the present invention, the reducing agent in step 2) is added to the reactor all at once, intermittently or continuously. In some embodiments of the present invention, the purification in step 4) can be carried out by atmospheric distillation or vacuum distillation according to the boiling point of the product.

[0029] In some embodiments of the present invention, the reactor uses a stirred vessel, an autoclave, a tubular reactor, a microreactor or a packed bubble column, preferably an autoclave.

[0030] Furthermore, the structural formula of the secondary amine is wherein R1 and R2 are independently selected from C1-C8 alkyl, C4-C8 cycloalkyl, aryl or C7-C9 alkylaryl, or R1, R2 and NH together form a C3-C7 ring; and / or, the aldehyde is selected from the group consisting of The monoaldehyde with the structural formula is The polymer of the monoaldehyde or the structural formula is The dialdehyde, wherein R3 is selected from H, C1-C6 alkyl, hydroxy-substituted C1-C6 alkyl, and R4 is selected from a single bond or C1-C4 alkylene.

[0031] The structural formula of the proton type ionic liquid is wherein R1 and R2 are independently selected from C1-C8 alkyl, C4-C8 cycloalkyl, aryl or C7-C9 alkylaryl, or R1, R2 and N together form a C3-C7 ring, n is selected from 1, 2 or 3, [X] n- Organic carboxylates selected from C1-C3, CO3 2- 、HCO3 - , Cl - 、NO3 - 、SO4 2- PO4 3- 、HPO4 2- or H2PO4 - .

[0032] The aldehyde is selected from the group consisting of The monoaldehyde with the structural formula is When the polymer of the monovalent aldehyde is prepared, the reaction formula of the protic ionic liquid and the aldehyde is as follows:

[0033]

[0034] The aldehyde is selected from the group consisting of When the dialdehyde is substituted by the proton type ionic liquid, the reaction formula of the proton type ionic liquid and the aldehyde is as follows:

[0035]

[0036] The proton type ionic liquid first reacts with the aldehyde to generate the corresponding Schiff base, and the Schiff base is reduced by a reducing agent to prepare the tertiary amine.

[0037] In some embodiments of the present invention, R1 and R2 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, sec-heptyl, n-octyl, isooctyl, sec-octyl, 2-ethylhexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl, phenyl, 2-naphthyl, 2-methyl Phenyl, 3-methylphenyl, 4-methylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 2,3,4-trimethylphenyl, 2,3,5-trimethylphenyl, 2,3,6-trimethylphenyl, 2,4,6-trimethylphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-n-propylphenyl, 3-n-propylphenyl or 4-n-propylphenyl.

[0038] In other embodiments of the present invention, R1, R2 and NH together form azetidine, pyrrole, piperidine, cycloheximide, morpholine, piperazine or N-methylpiperazine.

[0039] In some embodiments of the present invention, R3 is selected from H, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl, hydroxymethyl, hydroxyethyl, and hydroxypropyl.

[0040] In some embodiments of the present invention, the R4 is selected from a single bond, methylene, ethylene, propylene, and butylene.

[0041] In some embodiments of the present invention, the aldehyde is selected from acetaldehyde, paraldehyde, metaldehyde, propionaldehyde, glycoaldehyde, glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde or adipaldehyde.

[0042] In some embodiments of the present invention, the secondary amine is selected from dimethylamine, diisopropylamine, piperidine, morpholine or N-methylpiperazine; the aldehyde is selected from acetaldehyde, trimeraldehyde, tetramethylacetaldehyde, propionaldehyde, ethanolaldehyde or succinaldehyde; the tertiary amine is selected from dimethylethylamine, dimethylpropylamine, N,N,N',N'-tetramethylbutanediamine, diisopropylethylamine, diisopropylethanolamine, N-ethylpiperidine, N-propylmorpholine, N-propylpiperazine or N,N'-dipropylpiperazine.

[0043] In a particularly preferred embodiment of the invention, acetaldehyde and dimethylamine are reacted to form dimethylethylamine.

[0044] In a particularly preferred embodiment of the invention, propionaldehyde and dimethylamine are reacted to form dimethylpropylamine.

[0045] In a particularly preferred embodiment of the present invention, succinaldehyde and dimethylamine are reacted to form N,N,N',N'-tetramethylbutanediamine.

[0046] In a particularly preferred embodiment of the present invention, acetaldehyde and diisopropylamine are reacted to form diisopropylethylamine.

[0047] In a particularly preferred embodiment of the invention, paraldehyde and diisopropylamine are reacted to form diisopropylethylamine.

[0048] In a particularly preferred embodiment of the present invention, glycolaldehyde and diisopropylamine are reacted to form diisopropylethanolamine.

[0049] In a particularly preferred embodiment of the present invention, acetaldehyde and piperidine are reacted to form N-ethylpiperidine.

[0050] In a particularly preferred embodiment of the present invention, propionaldehyde and morpholine are reacted to form N-propylmorpholine.

[0051] In a particularly preferred embodiment of the present invention, propionaldehyde and piperazine are reacted to form N-propylpiperazine.

[0052] In a particularly preferred embodiment of the invention, propionaldehyde and piperazine are reacted to form N,N'-dipropylpiperazine.

[0053] In a particularly preferred embodiment of the present invention, acetaldehyde and dicyclohexylamine are reacted to form N-ethyldicyclohexylamine.

[0054] In a particularly preferred embodiment of the present invention, acetaldehyde and diphenylamine are reacted to form N-ethyldiphenylamine.

[0055] Compared with the prior art, the present invention has the following advantages:

[0056] The present invention creatively adds an acid to a system for generating tertiary amines using secondary amines as raw materials to react with the secondary amines to generate proton-type ionic liquids, and then reacts the proton-type ionic liquids with aldehydes to generate tertiary amines. The proton-type ionic liquids can play a self-catalytic role, so that the reaction system can achieve mild reaction conditions while ensuring high purity and high yield of the tertiary amine product, without the need for high pressure and hydrogen reaction atmosphere, and can use a mild and safe reducing agent. The purity of the tertiary amine product obtained by the present invention reaches 99%, and the yield reaches 98%. In addition, the reaction is a homogeneous autocatalytic reaction, and the production cost is also greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 The NMR spectra of diisopropylamine and the corresponding proton-type ionic liquids formed by diisopropylamine with formic acid, hydrochloric acid and sulfuric acid respectively;

[0058] Among them, diisopropylamine: H(DMSO) 0.93 (d, 12H), 2.80 (m, 2H), 3.32 (s, 2H).

[0059] Diisopropylammonium formate protic ionic liquid: δ H (DMSO) 1.18 (d, 12H), 3.31 (m, 2H), 8.80 (s, 1H).

[0060] Diisopropylammonium sulfate protic ionic liquid: δ H (DMSO)1.22(d,12H), 3.34(m,2H), 8.13(s,2H).

[0061] Diisopropylamine hydrochloride protic ionic liquid: δ H (DMSO) 1.25 (d, 12H), 3.31 (m, 2H), 8.89 (s, 2H). DETAILED DESCRIPTION

[0062] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0063] Various raw materials used in the following examples were purchased from Aladdin Reagent Company, wherein dimethylamine was an aqueous solution with a purity of 40%, diisopropylamine, piperidine, morpholine, ethylamine, dicyclohexylamine, paraldehyde, ethanolaldehyde, succinaldehyde, acetic acid, propionic acid and malonic acid were aqueous solutions with a purity of ≥99%, piperazine, diphenylamine, sodium formate, oxalic acid and sodium oxalate were solids with a purity of ≥99%, formic acid was a solid with a purity of ≥98%, hydrochloric acid was an aqueous solution with a purity of ≥36.5%, phosphoric acid was an aqueous solution with a purity of ≥85%, acetaldehyde, propionaldehyde and concentrated sulfuric acid were aqueous solutions with a purity of ≥98%, and concentrated nitric acid was an aqueous solution with a purity of ≥65%.

[0064] Example 1

[0065] Dimethylamine and acetaldehyde react to synthesize dimethylethylamine:

[0066] In a 100 mL high-pressure autoclave reactor, 15 g of a 40% dimethylamine aqueous solution was added, and 7.5 g of a formic acid solution was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of dimethylamine formate protic ionic liquid. Then, 10 g of sodium formate solid and 6.5 g of acetaldehyde solution were added to the protic ionic liquid aqueous solution. The reaction container was sealed, nitrogen was introduced to increase the pressure to 1 MPa, and the temperature was increased to 140° C. for reaction for 120 mins.

[0067] The reaction product mixture was distilled and purified by atmospheric distillation, and the fraction at 34-36° C. was collected. The purity of the fraction was analyzed by gas chromatography. The measurement procedure used in the gas chromatography was: separation column HP-1, length: 60 m, inner diameter: 0.25 mm, carrier: nitrogen, temperature program: 55° C., then increased by 10° C. per minute to 220° C., and finally maintained at 220° C. for 10 minutes to obtain dimethylethylamine with a purity of 99%, and the yield of the product was 95%.

[0068] Example 2

[0069] Dimethylamine and propionaldehyde form dimethylpropylamine

[0070] In a 100 mL high-pressure autoclave reactor, 15 g of a 40% dimethylamine aqueous solution was added, and 8 g of an acetic acid solution was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of dimethylamine acetate protic ionic liquid. Then, 10 g of a sodium formate solution and 8 g of a propionaldehyde solution were added to the protic ionic liquid aqueous solution. The reaction container was sealed, and nitrogen was introduced to increase the pressure to 2 MPa, and the temperature was increased to 160° C. for reaction for 120 mins.

[0071] The reaction product mixture was distilled and purified by atmospheric distillation, and the fraction at 70-71° C. was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1 to obtain dimethylpropylamine with a purity of 99%. The yield of the product was 96%.

[0072] Example 3

[0073] Dimethylamine and succinaldehyde form N,N,N',N'-tetramethylbutanediamine

[0074] In a 100 mL high-pressure autoclave reactor, 15 g of a 40% aqueous solution of dimethylamine was added, and 11 g of a propionic acid solution was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of dimethylamine propionate proton-type ionic liquid. Then, 13 g of oxalic acid and 5 g of butanedial were added to the proton-type ionic liquid aqueous solution. The reaction vessel was sealed, nitrogen was introduced to increase the pressure to 2 MPa, and the temperature was increased to 160° C. for reaction for 120 mins.

[0075] The reaction product mixture was distilled and purified by atmospheric distillation, and the fraction at 166-167° C. was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1 to obtain N,N,N',N'-tetramethylbutanediamine with a purity of 99%. The yield of the product was 95%.

[0076] Example 4

[0077] Diisopropylamine and acetaldehyde react to synthesize diisopropylethylamine:

[0078] In a 100 mL high pressure reactor, 15 g of diisopropylamine was added, and 15 g of concentrated hydrochloric acid was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of diisopropylamine hydrochloride proton type ionic liquid (its NMR spectrum in DMSO is shown in FIG. Figure 1 ), then add 10 g of sodium formate and 7 g of acetaldehyde to the protic ionic liquid aqueous solution, seal the reaction vessel, introduce nitrogen to increase the pressure to 2 MPa, and increase the temperature to 120° C. for 30 mins.

[0079] The reaction product mixture was distilled and purified by atmospheric distillation, and the fraction at 127-128° C. was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1, to obtain diisopropylethylamine with a purity of 99%, and the yield of the product was 97%.

[0080] Example 5

[0081] Diisopropylamine and triacetaldehyde react to synthesize diisopropylethylamine:

[0082] In a 100 mL high pressure reactor, 15 g of diisopropylamine was added, and an aqueous solution containing 7 g of formic acid was added to the reactor and stirred to form a uniform solution to prepare an aqueous solution of diisopropylamine formate proton type ionic liquid (its NMR spectrum in DMSO is shown in FIG. Figure 1 ), then add 7g formic acid and 7g paraldehyde to the protic ionic liquid aqueous solution, seal the reaction vessel, introduce nitrogen, maintain normal pressure (i.e., the pressure indication is 0 MPa), increase the temperature to 160°C and react for 120 mins.

[0083] After the reaction, the oil and water layers are separated, and the water layer can be directly recycled and distilled at atmospheric pressure to collect the fraction at 127-128° C. The fraction is analyzed for purity by gas chromatography in the same manner as in Example 1 to obtain diisopropylethylamine with a purity of 99%, and the yield of the product is 98%.

[0084] Example 6

[0085] Diisopropylamine and ethanolaldehyde react to synthesize diisopropylethanolamine:

[0086] In a 100 mL high pressure reactor, 15 g of diisopropylamine was added, and an aqueous solution containing 12 g of concentrated sulfuric acid (10% content) was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of diisopropylamine sulfate proton type ionic liquid (its NMR spectrum in DMSO is shown in FIG. Figure 1 ), then add 10 g of sodium formate and 9 g of ethanolaldehyde to the protic ionic liquid aqueous solution, seal the reaction vessel, introduce nitrogen to increase the pressure to 2 MPa, and increase the temperature to 120° C. for 30 mins.

[0087] The reaction product mixture was distilled and purified by atmospheric distillation, and the fractions at 187-192° C. were collected. The fractions were analyzed for purity by gas chromatography in the same manner as in Example 1, and diisopropylethanolamine with a purity of 99% was obtained. The yield of the product was 94%.

[0088] Example 7

[0089] Piperidine and acetaldehyde react to synthesize N-ethylpiperidine:

[0090] In a 100 mL high-pressure reactor, 8.5 g of piperidine was added, and an aqueous solution containing 10 g of phosphoric acid (10% content) was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of piperidine phosphate proton type ionic liquid, and then 5.0 g of formic acid and 4.6 g of acetaldehyde were added to the proton type ionic liquid aqueous solution, the reaction container was sealed, nitrogen was introduced to increase the pressure to 2 MPa, and the temperature was increased to 160° C. for reaction for 90 mins.

[0091] The reaction product mixture was distilled and purified by atmospheric distillation, and the fraction at 126-129° C. was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1, to obtain N-ethylpiperidine with a purity of 99%, and the yield of the product was 94%.

[0092] Example 8

[0093] The reaction of morpholine and propionaldehyde to synthesize N-propylmorpholine:

[0094] In a 100 mL high-pressure autoclave reactor, 15 g of morpholine was added, and 17 g of concentrated hydrochloric acid was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of morpholine hydrochloride proton-type ionic liquid. Then, 12 g of sodium formate and 11 g of propionaldehyde were added to the proton-type ionic liquid aqueous solution. The reaction container was sealed, nitrogen was introduced to increase the pressure to 2 MPa, and the temperature was increased to 160° C. for reaction for 120 mins.

[0095] The reaction product mixture was purified by distillation under reduced pressure, and the fraction at 67-69° C. under 30 mmHg pressure was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1 to obtain N-propylmorpholine with a purity of 99%. The yield of the product was 90%.

[0096] Example 9

[0097] The synthesis of N-propylpiperazine by the reaction of piperazine and propionaldehyde:

[0098] In a 100mL high-pressure reactor, 15g of piperazine was added, and an aqueous solution containing 18g of concentrated nitric acid (10% content) was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of piperazine nitrate proton type ionic liquid. Then, 12g of sodium formate was added to the proton type ionic liquid aqueous solution, and the reaction container was sealed. Nitrogen was introduced to increase the pressure to 2MPa. After the temperature was increased to 160°C, 10g of propionaldehyde was introduced within 1 hour and the reaction was reacted for 120mins.

[0099] The reaction product mixture was purified by distillation and vacuum distillation, and the fraction at 61-64° C. under a pressure of 15 mmHg was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1 to obtain N-propylpiperazine with a purity of 99%. The yield of the product was 91%.

[0100] Example 10

[0101] Piperazine and propionaldehyde react to synthesize N,N'-dipropylpiperazine:

[0102] In a 100mL high-pressure reactor, 15g of piperazine was added, and an aqueous solution containing 18g of concentrated nitric acid (10% content) was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of piperazine nitrate proton ionic liquid. Then, 24g of sodium formate and 20g of propionaldehyde were added to the proton ionic liquid aqueous solution. The reaction container was sealed, nitrogen was introduced to increase the pressure to 2MPa, and the temperature was increased to 160°C for reaction for 120mins.

[0103] The reaction product mixture was purified by distillation and vacuum distillation, and the fraction at 84-88° C. under a pressure of 12 mmHg was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1 to obtain N,N'-dipropylpiperazine with a purity of 99%. The yield of the product was 90%.

[0104] Embodiment 11

[0105] Synthesis of N,N,N',N'-tetramethylbutanediamine from dimethylamine and succinaldehyde:

[0106] In a 100mL high-pressure autoclave reactor, 15g of a 40% aqueous solution of dimethylamine was added, and 14g of an aqueous solution of malonic acid was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of dimethylamine malonate proton-type ionic liquid. Then, 13g of oxalic acid was added to the proton-type ionic liquid aqueous solution, and the reaction container was sealed, and nitrogen was introduced to increase the pressure to 2MPa, and the temperature was increased to 160°C for reaction for 120mins, wherein 5g of succinaldehyde was uniformly injected into the reaction system within the first 60mins.

[0107] The reaction product mixture was distilled and purified by atmospheric distillation, and the fraction at 166-167° C. was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1 to obtain N,N,N',N'-tetramethylbutanediamine with a purity of 99%. The yield of the product was 96%.

[0108] Example 12

[0109] Synthesis of N-ethyldicyclohexylamine from acetaldehyde and dicyclohexylamine:

[0110] In a 100 mL high-pressure autoclave reactor, 24 g of dicyclohexylamine aqueous solution was added, 14 g of concentrated hydrochloric acid was added dropwise into the reactor, and stirred to form a uniform solution to prepare an aqueous solution of dicyclohexylamine hydrochloride proton ionic liquid, and then 10 g of sodium formate and 7 g of acetaldehyde were added to the proton ionic liquid aqueous solution. The reaction container was sealed, nitrogen was introduced to increase the pressure to 2 MPa, and the temperature was increased to 160°C for reaction for 120 mins.

[0111] The reaction product mixture was purified by vacuum distillation, and the fraction at 137-138° C. under a pressure of 14 mmHg was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1 to obtain N-ethyldicyclohexylamine with a purity of 99%. The yield of the product was 94%.

[0112] Example 13

[0113] Synthesis of N-ethyldiphenylamine from acetaldehyde and diphenylamine:

[0114] In a 100 mL high-pressure reactor, 23 g of diphenylamine solid was added, and an aqueous solution containing 12 g of concentrated sulfuric acid (10% content) was added dropwise into the reactor and stirred to form a uniform solution to prepare an aqueous solution of diphenylamine sulfate protic ionic liquid. Then, 15 g of oxalic acid and 6 g of acetaldehyde were added to the protic ionic liquid aqueous solution, and the reaction container was sealed, nitrogen was introduced to increase the pressure to 2 MPa, and the temperature was increased to 160° C. for reaction for 120 mins.

[0115] The reaction product mixture was purified by vacuum distillation, and the fraction at 150-152° C. under a pressure of 14 mmHg was collected. The fraction was analyzed for purity by gas chromatography in the same manner as in Example 1 to obtain N-ethyldiphenylamine with a purity of 99%. The yield of the product was 92%.

[0116] Embodiment 14

[0117] Synthesis of triethylamine from diethylamine and acetaldehyde

[0118] In a 100 mL high-pressure autoclave reactor, 10 g of diethylamine was added, and then 4.5 g of formic acid was added dropwise to prepare an aqueous solution of diethylamine formate protic ionic liquid. Then, 19 g of sodium oxalate solid and 6.5 g of acetaldehyde were added to the protic ionic liquid aqueous solution. The reaction vessel was sealed, nitrogen was introduced to increase the pressure to 2 MPa, and the temperature was increased to 120°C for reaction for 120 mins.

[0119] After the reaction is completed, the residual gas in the reactor is removed and the reaction product mixture is analyzed by gas chromatography. The gas chromatography method is the same as that in Example 1.

[0120] Gas chromatography analysis showed that the reaction system contained diethylamine, that is, diethylamine was generated by ethylamine and acetaldehyde under the reduction of sodium formate. The reaction product mixture was rectified and purified, and the fraction at 89-91° C. was collected under normal pressure to obtain triethylamine with a purity of 99%, and the yield of the product was 94%.

[0121] Comparative Example 1

[0122] The reaction of diisopropylamine and acetaldehyde:

[0123] In a 100 mL high-pressure autoclave reactor, 15 g of diisopropylamine was added, followed by 11 g of sodium formate and 7 g of acetaldehyde. The reaction vessel was sealed, nitrogen was introduced to increase the pressure to 2 MPa, and the temperature was increased to 120° C. for reaction for 120 mins.

[0124] After the reaction is completed, the residual gas in the reactor is removed, and the reaction product mixture is analyzed by gas chromatography. The gas chromatography is the same as that in Example 1. Through gas chromatography analysis, only sample peaks of acetaldehyde and diisopropylamine are found in the reaction product mixture, indicating that diisopropylethylamine is not generated in the reactor. Comparison of Comparative Example 1 and Example 4 shows that the acid and secondary amine added in the present invention form a protic ionic liquid, which is easy to react with aldehyde to form a Schiff base, and then reduced to a tertiary amine by a reducing agent. When no acid is added, the system does not form a protic ionic liquid, and the secondary amine and aldehyde cannot react.

[0125] Comparative Example 2

[0126] Ethylamine and acetaldehyde react to synthesize diethylamine:

[0127] In a 100 mL high-pressure autoclave reactor, 7 g of ethylamine was added, followed by 23 g of solid sodium formate and 14 g of acetaldehyde. The reaction vessel was sealed, nitrogen was introduced to increase the pressure to 2 MPa, and the temperature was increased to 120° C. for reaction for 120 mins.

[0128] After the reaction is completed, the residual gas in the reactor is removed and the reaction product mixture is analyzed by gas chromatography. The gas chromatography method is the same as that in Example 1.

[0129] Gas chromatography analysis showed that the reaction system contained diethylamine, that is, diethylamine was generated by ethylamine and acetaldehyde under the reduction of sodium formate. The reaction product mixture was rectified and purified, and the fraction at 55-56° C. was collected under normal pressure to obtain diethylamine with a purity of 99%, and the yield of the product was 55%.

[0130] Generally, the reaction of primary amine and aldehyde to generate secondary amine is easier to carry out than the reaction of corresponding secondary amine and aldehyde to generate tertiary amine, which is manifested in that the yield of primary amine and aldehyde to generate secondary amine is higher than the yield of corresponding tertiary amine generated by secondary amine as raw material. Comparative Example 2 is the reaction of primary amine diethylamine and acetaldehyde to generate secondary amine diethylamine, and its yield is significantly lower than the yield of the tertiary amine triethylamine generated by the reaction of diethylamine and formic acid with formic acid proton type ionic liquid, and the ionic liquid is then reacted with acetaldehyde and reduced to generate tertiary amine triethylamine, which indicates that in the present invention, when the proton type ionic liquid reacts with aldehyde and generates tertiary amine through reduction, the proton type ionic liquid not only participates in the reaction itself but also has a certain catalytic effect on the reaction.

[0131] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0132] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. A method for preparing tertiary amines using secondary amines as raw materials, characterized in that: The method comprises the steps of reacting a secondary amine as a raw material with an acid to generate a proton type ionic liquid, and reacting the proton type ionic liquid with an aldehyde under the action of a reducing agent to generate a tertiary amine; the acid is selected from a combination of one or more of C1-C3 organic carboxylic acids, hydrochloric acid, sulfuric acid, carbonic acid, phosphoric acid and nitric acid; the reducing agent is selected from a combination of one or more of formic acid, sodium formate, oxalic acid, sodium oxalate and triphenylsilane; the molar ratio of the secondary amine to the acid is 0.2-1.5; the molar ratio of the aldehyde to the proton type ionic liquid is 0.2-5.0; the molar ratio of the reducing agent to the proton type ionic liquid is 1.0-5.0; the reaction time of the proton type ionic liquid and the aldehyde under the action of the reducing agent is 5-120 minutes; the aldehyde is selected from a structural formula of The monoaldehyde with the structural formula is The polymer of the monoaldehyde or the structural formula is wherein R3 is selected from H, C1-C6 alkyl, hydroxy-substituted C1-C6 alkyl, and R4 is selected from a single bond or C1-C4 alkylene; the structural formula of the secondary amine is The R1 and R2 are independently selected from isopropyl, cyclohexyl, and phenyl, or R1, R2 and NH form piperidine, morpholine, and piperazine; the structural formula of the proton-type ionic liquid is wherein R1 and R2 are independently selected from isopropyl, cyclohexyl, and phenyl, or R1 and R2 together with NH form piperidine, morpholine, or piperazine, and n is selected from 1, 2, or 3, [X] n- Organic carboxylates selected from C1-C3, CO3 2- 、HCO3 - , Cl - 、NO3 - 、SO4 2- PO4 3- 、HPO4 2- or H2PO4 - .

2. The method for preparing tertiary amine using secondary amine as raw material according to claim 1, characterized in that: The molar ratio of the secondary amine to the acid is 0.3-1.

4.

3. The method for preparing tertiary amine using secondary amine as raw material according to claim 1, characterized in that: The reducing agent is selected from formic acid, sodium formate, oxalic acid or sodium oxalate.

4. The method for preparing tertiary amine using secondary amine as raw material according to claim 1, characterized in that: The molar ratio of the aldehyde to the protic ionic liquid is 0.3-3.0; and / or the molar ratio of the reducing agent to the protic ionic liquid is 1.0-2.

0.

5. The method for preparing tertiary amine using secondary amine as raw material according to claim 1, characterized in that: The molar ratio of the secondary amine to the acid is 0.4-1.2; and / or the molar ratio of the aldehyde to the protic ionic liquid is 0.4-2.

0.

6. The method for preparing tertiary amine using secondary amine as raw material according to claim 1, characterized in that: The step of using secondary amine as a raw material to react with an acid to generate a proton-type ionic liquid is carried out at room temperature and normal pressure.

7. The method for preparing tertiary amine using secondary amine as raw material according to claim 1, characterized in that: The step of reacting the proton type ionic liquid and aldehyde to generate tertiary amine under the action of a reducing agent is carried out at a pressure of 0-5.0 MPa; and / or, the step of reacting the proton type ionic liquid and aldehyde to generate tertiary amine under the action of a reducing agent is carried out at a temperature of 60-200°C.

8. The method for preparing tertiary amine using secondary amine as raw material according to claim 1, characterized in that: The step of reacting the proton type ionic liquid and aldehyde to generate tertiary amine under the action of a reducing agent is carried out at a pressure of 0-3.0 MPa; and / or, the step of reacting the proton type ionic liquid and aldehyde to generate tertiary amine under the action of a reducing agent is carried out at a temperature of 120-160°C.

9. The method for preparing tertiary amine using secondary amine as raw material according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: 1) adding the acid dropwise to the secondary amine or adding the secondary amine dropwise to the acid to form the protic ionic liquid; 2) adding the proton type ionic liquid and the reducing agent into a reactor, and adding the aldehyde into the reactor; 3) introducing nitrogen until the pressure of the reaction system is 0-5.0 MPa, raising the temperature to 60-200° C., and reacting for 5-120 mins; 4) After the reaction is completed, the reaction system is purified to obtain the tertiary amine.

10. The method for preparing tertiary amine using secondary amine as raw material according to claim 9, characterized in that: In the step 1), the acid is added dropwise to the aqueous solution of the secondary amine to form the protic ionic liquid; and / or, in the step 1), the acid is added dropwise to the secondary amine in the form of an aqueous solution of the acid; and / or, in the step 2), the aldehyde is added to the reactor all at once, intermittently or continuously; and / or, in the step 2), the reducing agent is added to the reactor all at once, intermittently or continuously; and / or, in the step 4), the purification is atmospheric distillation or vacuum distillation.

11. The method for preparing tertiary amine using secondary amine as raw material according to claim 1, characterized in that: The R3 is selected from H, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl, hydroxymethyl, hydroxyethyl, hydroxypropyl; and / or, the R4 is selected from a single bond, methylene, ethylene, propylene, butylene; and / or, the aldehyde is selected from acetaldehyde, trimeraldehyde, tetramethyl acetaldehyde, propionaldehyde, ethanolaldehyde, glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde or adipaldehyde.

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