CN105384654B - A kind of crystallization purifications of hydroxyalkyl amide - Google Patents

Abstract

The present invention relates to the crystallization purifications of hydroxyalkyl amide, the hydroxyalkyl amide is formed by the reaction product crystallization purifying of the dialkanol amine under base catalyst existence condition and carboxylic adipate, and crystallization purifications comprise the following steps：a）A certain amount of recrystallisation solvent is added into reaction product；b）Stirring and dissolving backflow is cooled to less than 90 DEG C；c）Water-bath is cooled to 20 30 DEG C, separates out product initial crystallization；d）It is filled with liquid nitrogen and is cooled further to 25 ~ 5 DEG C, separates out target product sufficient crystallising；e）Filtering, drying, obtain the hydroxyalkyl amide product after crystallization purifying；f）The mother liquor after filtering is reclaimed, continuation is used as next group recrystallisation solvent.It is abundant that this method can separate out the product in recrystallisation solvent, and being recycled for multiple times for crystallization Mother liquor can be achieved, and can effectively reduce the deterioration of Recycling Mother Solution product quality, can significantly improve product yield and product quality.

Description

A kind of crystallization purification method of hydroxyalkylamide

technical field

The invention belongs to the technical field of purification of reaction products, and relates to a method for crystallization and purification of reaction products, in particular to a method for crystallization and purification of reaction products of dialkanolamine and dialkyl carboxylic acid in the presence of a basic catalyst.

Background technique

Hydroxyalkyl amides are obtained by the amidation reaction of dialkanolamines with dialkyl carboxylic acids under base catalysis. Among them, the reaction product generally contains residual dialkanolamine, residual basic catalyst and other by-products. At the same time, the crystallization of the reaction product is generally based on the method of cooling crystallization with cold water, and the crystallization rate is not high. The solvent recovered after crystallization participates in When the next batch is recycled, the residual product in the solvent will undergo changes such as yellowing, which will affect the quality of the subsequent product, resulting in a low overall product yield and poor product quality.

Contents of the invention

The purpose of the present invention is to solve the above-mentioned problems existing in the prior art, and to provide a crystallization purification method, which can fully precipitate the product in the crystallization solvent, realize multiple recycling of the mother liquor after crystallization, and effectively reduce the amount of the mother liquor The quality of recycled products deteriorates, which can significantly improve product yield and product quality.

In order to achieve the above object, the present invention provides the following technical scheme: a method for crystallization and purification of hydroxyalkylamides, wherein the hydroxyalkylamides are prepared from dialkanolamine and dialkyl carboxylate in the presence of a basic catalyst The reaction product is crystallized and purified, and the crystallization purification method comprises the following steps:

a) adding an amount of crystallization solvent to said reaction product;

b) Stir to dissolve and reflux to cool down to below 90°C;

c) Cool in a water bath to 20-30°C to make the product crystallize initially;

d) Fill with liquid nitrogen and further cool down to -25~-5°C to fully crystallize the target product;

e) filtering and drying to obtain crystallized and purified hydroxyalkylamide products;

f) Recover the filtered mother liquor and continue to use it as the next batch of crystallization solvent.

Further, wherein, the basic catalyst is sodium methoxide; the general formula of the dialkanolamine is HN(ROH)2, wherein R is an alkyl group with carbon atoms from 1 to 6; the carboxylic acid di The general formula of alkyl esters is R'OCOR''COOR', wherein R' is an alkyl group having 1 to 4 carbon atoms, and R'' is an alkyl group having 3 to 18 carbon atoms.

Further, wherein, the molar ratio of the dialkyl carboxylate to the dialkanolamine is 1:2 to 1:2.1; the dialkyl carboxylate to the basic catalyst is The mass ratio is 1:0.00001~1:0.05.

Still further, wherein, the crystallization solvent is one or more of methanol, acetone, and isopropanol; the mass ratio of the dialkyl carboxylate to the crystallization solvent is 1:3~1: 5.

The crystallization and purification method of hydroxyalkylamides of the present invention adopts the method of filling liquid nitrogen and further cooling to low-temperature crystallization after conventional cooling, that is, the reacted reaction product is heated and dissolved in a crystallization solvent first, and then conventionally cooled to room temperature Preliminary crystallization, then filled with liquid nitrogen and further cooled to low temperature, at the same time, it acts as an inert protection for the product crystallization, so that the target product can be fully crystallized and precipitated. After the product is filtered out, the mother liquor is recovered, and the recovered mother liquor continues to be circulated as the next batch of crystallization solvents use. Therefore, the method for crystallization and purification of hydroxyalkylamides of the present invention can fully precipitate the product in the crystallization solvent, can realize multiple recycling of the mother liquor after crystallization, can effectively reduce the quality deterioration of the mother liquor circulation product, and can obviously increase the product yield and product quality.

detailed description

The present invention will be further described below in conjunction with the examples, and the contents of the examples are not intended to limit the protection scope of the present invention.

Example [1]

(1) In a distillation flask, add 315g (3mol) of diethanolamine and 5g of 30% sodium methoxide, then set up a distillation device, and add 261g (1.5mol) of dimethyl adipate dropwise at 100°C with stirring, Added about 2h, and keep the reaction for 2h, -0.05MPa distilled methanol. After 2 hours, the temperature was raised to 104°C, the pressure was reduced to -0.09 MPa, the temperature and vacuum were maintained, the reaction was stirred for 1 hour, the heating was stopped, and the reaction product was obtained after the vacuum was released. Put the reaction product into the reflux device, carefully add 1000g of isopropanol dropwise, stir to dissolve and reflux to lower the temperature to below 90°C, cool to 25°C in a water bath to make the product initially crystallize, fill it with liquid nitrogen and further cool to -15°C, filter, and dry dry to obtain 450.6 g of crystalline product, and reclaim the filtrate;

(2) Using the recovered filtrate of step (1) as the crystallization solvent, repeat the operation of step (1) to obtain 484.12 g of the crystallized product, and recover the filtrate;

(3) Using the filtrate recovered from step (2) as the crystallization solvent, the operation of (2) was repeated to obtain 488.71 g of the crystallized product.

Comparative example [1]

(1) In a distillation flask, add 315g (3mol) of diethanolamine and 5g of 30% sodium methoxide, then set up a distillation device, and add 261g (1.5mol) of dimethyl adipate dropwise at 100°C for about 2 hours After the addition, keep the reaction for 2h and distill methanol at -0.05MPa. After 2 hours, the temperature was raised to 104°C, the pressure was reduced to -0.09 MPa, the temperature and vacuum were maintained, the reaction was stirred for 1 hour, the heating was stopped, and the reaction product was obtained after the vacuum was released. Put the reaction product into the reflux device, carefully add 1000g of isopropanol dropwise, stir to dissolve and reflux to cool down to below 90°C, use cold water to slowly cool the crystallization, further cool to 20°C, filter, and dry to obtain 421g of the crystallized product, and recover the filtrate;

(2) Recovering the filtrate from step (1) as the crystallization solvent, repeating the operation of step (1) to obtain 466.65 g of the crystallized product, and recovering the filtrate;

(3) The filtrate recovered in step (2) was used as the crystallization solvent, and the operation of step (2) was repeated to obtain 482.1 g of the crystallized product.

Comparative analysis of the results: when the reaction product is crystallized and cooled by filling with liquid nitrogen, the yields of the three batches of reaction products are 93.87%, 100.85%, and 101.81% respectively; , 100.44%, it can be seen that it is filled with liquid nitrogen for cooling, and the yield of the reaction product is obviously improved. And according to the national standard GB/T 27807-2001 of the People's Republic of China "Appendix C Determination of Hydroxyalkyl Amide Content" method, the purity of the three batches of reaction products in Example [1] was measured to be 93%, 92.7%, 92.5%, respectively, and cooled by cold water The purity of the three batches of crystallized reaction products were 93.5%, 89.6%, 86.7% respectively. It can be seen that after filling with liquid nitrogen, the yield and purity of the reaction product are significantly improved.

Example [2]

(1) In a distillation flask, add 402g (3mol) of diisopropanolamine and 5g of 30% sodium methoxide, then set up a distillation device, and add 1,4-cyclohexyldicarboxylic acid dicarboxylate dropwise at 100°C Add 300g (1.5mol) of methyl ester, finish adding in about 2h, keep warm for 2h, distill methanol at -0.05MPa. After 2 hours, the temperature was raised to 104°C, the pressure was reduced to -0.09 MPa, the temperature and vacuum were maintained, the reaction was stirred for 1 hour, the heating was stopped, and the reaction product was obtained after the vacuum was released. Put the reaction product into the reflux device, carefully add 1200g of methanol dropwise, stir to dissolve and reflux to cool down to below 90°C, cool in a water bath to 25°C to make the product initially crystallize, fill it with liquid nitrogen and further cool to -15°C, filter, and dry. Obtain 508.12 g of crystalline product, and recover the filtrate;

(2) Using the recovered filtrate of step (1) as the crystallization solvent, repeat the operation of step (1) to obtain 547.5 g of the crystallized product, and recover the filtrate;

(3) Using the recovered filtrate of step (2) as the crystallization solvent, the operation of step (2) was repeated to obtain 554.71 g of the crystallized product.

Comparative example [2]

(1) In a distillation flask, add 402g (3mol) of diisopropanolamine and 5g of 30% sodium methoxide, then set up a distillation device, and add 300g (1.5mol) of dimethyl adipate dropwise under stirring at 100°C , Added about 2h, and kept the reaction for 2h, -0.05MPa distilled methanol. After 2 hours, the temperature was raised to 104°C, the pressure was reduced to -0.09 MPa, the temperature and vacuum were maintained, the reaction was stirred for 1 hour, the heating was stopped, and the reaction product was obtained after the vacuum was released. Put the reaction product into the reflux device, carefully add 1200g of methanol dropwise, stir to dissolve and reflux to cool down to below 90°C, use cold water to slowly cool the crystallization, further cool to 20°C, filter, and dry to obtain 472.74g of the crystallized product, and recover the filtrate;

(2) Using the recovered filtrate of step (1) as the crystallization solvent, repeat the operation of step (1) to obtain 528.04 g of the crystallized product, and recover the filtrate;

(3) Using the recovered filtrate of step (2) as the crystallization solvent, the operation of step (2) was repeated to obtain 544.46 g of the crystallized product.

Comparative analysis of the results: when the product is cooled by filling liquid nitrogen during crystallization, the yields of the three batches of products are 88.77%, 95.65%, and 96.91% respectively; , it can be seen that the product yield is obviously improved by filling with liquid nitrogen for cooling. And according to the National Standard GB/T27807-2001 of the People's Republic of China "Appendix C Determination of Hydroxyalkyl Amide Content" method, the purity of the three batches of products in Example [2] was measured to be 93.4%, 93.1%, and 92.6%, respectively. The purity of the batch products were 93.7%, 91.6%, 86.7%, respectively. It can be seen that after filling with liquid nitrogen, the yield and purity of the product are significantly improved.

The crystallization and purification method of hydroxyalkylamides of the present invention adopts the method of filling liquid nitrogen and further cooling to low-temperature crystallization after conventional cooling, that is, the reacted reaction product is heated and dissolved in a crystallization solvent first, and then conventionally cooled to room temperature Preliminary crystallization, then filled with liquid nitrogen and further cooled to low temperature, at the same time, it acts as an inert protection for the product crystallization, so that the target product can be fully crystallized and precipitated. After the product is filtered out, the mother liquor is recovered, and the recovered mother liquor continues to be circulated as the next batch of crystallization solvents use. Therefore, the method for crystallization and purification of hydroxyalkylamides of the present invention can fully precipitate the product in the crystallization solvent, can realize multiple recycling of the mother liquor after crystallization, can effectively reduce the quality deterioration of the mother liquor circulation product, and can obviously increase the product yield and product quality.

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, on the basis of the above description, other changes or changes in different forms can also be made. All the implementation manners cannot be exhaustively listed here. All obvious changes or variations derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims (1)

1. A method for crystallization and purification of hydroxyalkylamides, said hydroxyalkylamides are formed by crystallization and purification of the reaction product of dialkanolamine and dialkyl carboxylic acid in the presence of a basic catalyst, the crystallization purification The method includes the following steps: a) adding a certain amount of crystallization solvent to the reaction product; b) stirring, dissolving and refluxing to lower the temperature to below 90°C; c) Cooling in a water bath to 20-30°C to make the product crystallize initially; d) Filling with liquid nitrogen and further cooling to -25～-5°C, so that the target product can be fully crystallized and precipitated; e) filtering and drying to obtain crystallized and purified hydroxyalkylamide products; f) reclaim the mother liquor after filtration, continue as the next batch of crystallization solvent; The crystallization solvent is one or more of methanol, acetone, and isopropanol, and the mass ratio of the dialkyl carboxylate to the crystallization solvent is 1:3 to 1:5; the basic The catalyst is sodium methoxide, the general formula of the dialkanolamine is HN(ROH) ₂ , wherein R is an alkyl group with a carbon number from 1 to 6, and the general formula of the dialkyl carboxylate is R'OCOR"COOR', wherein R' is an alkyl group with a carbon number from 1 to 4, and R" is an alkyl group with a carbon number from 3 to 18; the dialkyl carboxylic acid and the dialkanolamine The molar ratio of the carboxylic acid dialkyl ester to the basic catalyst is 1:2 to 1:2.1; the mass ratio of the dialkyl carboxylic acid to the basic catalyst is 1:0.00001 to 1:0.05.