CH687984A5 - Single-stage prepn. of betaine from lactone - Google Patents

Abstract

Prepn. of betaines of formula <+>NRR'R"-A-COO<-> (I) involves reacting a lactone of formula (II) with a tert. amine of formula NRR'R" (III) in the presence of water at 50-250 (pref. 120-200) deg C. R = 1-22C alkyl; R', R" = 1-4C alkyl; A = -(CR1R2)n-; n = 3-5; R1, R2 = H or 1-4C alkyl (same or different at each occurrence).

Description

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description

The present invention relates to a process for the production of betaines from lactones and tertiary amines.

Betaines, especially y-butyrobetaine, are important chemical intermediates. For example, f-butrobetain (inner salt of 3-carboxy-N, N, N-trimethyl-1-propanaminium hydroxide) is used to produce L-carnitine in a microbiological way (EP 158 194, EP 195 944). A technical process for the production of fButyrobetain starts from y-butyrolactone, which is first converted to chlorobutyric acid. This is then esterified, converted into the chloride of trimethylam moniobutyric acid ester with trimethylamine and finally saponified to give y-butyrobetaine (EP 360 222). A disadvantage of the process is the formation of salts (e.g. NaCl) and aqueous alcohol during the saponification, and the fact that the process comprises four reaction steps and the isolation of at least one intermediate.

Betaines with a longer alkyl chain on the nitrogen atom are amphoteric surfactants. They are also prepared from (o-halocarboxylic acid esters and the corresponding tertiary amines (see e.g. JP-A 56/25 139, Chem. Abstr. 95: 80176 m), the disadvantages already mentioned occurring.

The object of the present invention was therefore to provide a simpler process which delivers as little waste or by-products as possible.

According to the invention, this object is achieved by the method according to claim 1. It has been found that it is possible under suitable reaction conditions, betaines of the general formula

RR'R "N + A COO" I

wherein R is a Cr-C22-alkyl group, R 'and R "independently of one another in each case Ct-C4-alkyl and A is a carbon chain with 3 to 5 links of the formula -CR1R2-CR3R4-CR5R6-

-CR1R2-CR3R4_CR5R6_CR7R8_ or -CR1R2-CR3R4-CR5R6 — CR7R8-CR9R10 and R 1 to R 10 each independently represent hydrogen or a C 1 -C 4 -alkyl group, in one step from the corresponding lactones of the general formula

O

and the corresponding tertiary amines of the general formula RR'R "N III

in which R, R ', R "and A have the meaning given above. Ideally, no waste products are produced in this reaction.

According to the invention, the lactone (II) is reacted with the amine (III) at a temperature of 50 to 250 ° C., preferably at 120 to 200 ° C., in the presence of water. This course of the reaction is surprising because it was known that N-methyl-2-pyrrolidone is obtained from 7-butyrolactone and trimethylamine at high temperatures in the presence of water (JP-A 01/186 863).

Suitable starting materials for the process according to the invention are, according to the general formula II, y, 5- and e-lactones, that is to say lactones with 5-7 ring members, such as, for example, y-butyrolactone, 5-valerolactone or e-caprolactone. These can be substituted on the carbon atoms (with the exception of car bonyl carbon) with Ci-C <i-alkyl groups such as y-valerolactone. The y-butyrolactone is particularly preferred as the lactone (II).

The tertiary amines of the general formula III used are preferably those with straight-chain alkyl groups, ie trimethylamine, triethylamine, tripropylamine or tri-n-butylamine. The alkyl groups can also be different, in particular an alkyl group can be long-chain, that is to say, for example, contain 8 to 22 carbon atoms. In this case the other two alkyl groups are preferably methyl. These compounds are known under the name “tertiary fatty amines”, the long-chain alkyl group usually being derived from one of the natural fatty acids with an even carbon number. Trimethylamine is particularly preferred.

A basic catalyst is preferably added to the reaction mixture. As a result, a shorter reaction time and / or an improved yield can be achieved. Alkaline or alkaline earth metal hydroxides such as, for example, lithium hydroxide, sodium hydroxide or calcium hydroxide or alkali metal salts of weak acids such as, for example, alkali metal or alkaline earth metal, are particularly suitable as basic catalysts.

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potassium carbonates or alkali hydrogen carbonates, namely sodium carbonate, calcium carbonate, basic magnesium carbonate or sodium hydrogen carbonate. The addition of lithium hydroxide has proven to be particularly advantageous.

The reaction of the lactone (II) with the amine (III) can be carried out in an inert solvent or without an additional solvent. Excess lactone is preferably used as the solvent.

To work up the reaction mixture, the solvent and / or excess lactone is preferably first distilled off. The residue which contains the desired betaine can then be processed further in a manner known per se, for example by electrodialysis (EP 0 360 222).

In addition to the betaine, the residue also contains the corresponding hydroxy acid, which is formed by hydrolysis of the lactone, in the form of its trimethylammonium salt and / or its salt with the base optionally added as a catalyst. This salt can be isolated and used again in the reaction, so it does not constitute waste. If, for example, lithium hydroxide is used as the base, the lithium salt of the hydroxy acid formed can be used in a new reaction mixture instead of lithium hydroxide.

The following examples illustrate the implementation of the method according to the invention, without any restriction to the embodiments described therein.

Example 1 (comparative example without water and without catalyst)

A mixture of 43.1 g (0.5 mol) of y-butyrolactone and 2.93 g (0.05 mol) of trimethylamine was heated at 160 ° C. in a 120 ml autoclave for 5 hours. After cooling, the contents of the autoclave were analyzed; it contained no y-butyrobetaine and consisted of the unchanged starting materials.

Example 2

In an autoclave, 21.6 g (0.25 mol) of y-butyrolactone were heated to 160 ° C. for 5 hours with 20 g of water and 3.34 g of 45% aqueous trimethylamine solution (25 mmol of trimethylamine). After cooling, the y-butyrobetaine content of the reaction mixture was determined to be 4.6%, corresponding to a yield (based on trimethylamine) of 56%.

Example 3

The procedure was as in Example 2, but with a reaction time reduced to 2.5 h. The y-butyrobetaine content of the reaction mixture was then 3.7%, corresponding to a yield of 45%.

Example 4

The procedure was as in Example 3, with 6.7 g (0.16 mol) of lithium hydroxide monohydrate being added to the reaction mixture. The content of y-butyrobetaine in the reaction mixture after the reaction was 5.5%, corresponding to a yield of 77%.

Example 5

The procedure was as in Example 3, using a mixture of 3.8 g of water, 16.0 g of 1N sodium hydroxide solution (15 mmol of NaOH) and 2.17 g (25 mmol) of lithium bromide instead of pure water. The content of y-butyrobetaine in the reaction mixture after the reaction was 4.1%, corresponding to a yield of 52%.

Example 6

The procedure was as in Example 3, using a mixture of 19.6 g of water, 0.34 g (8 mmol) of lithium hydroxide monohydrate and 1.06 g (12 mmol) of lithium bromide instead of pure water. The y-butyrobetaine content of the reaction mixture after the reaction was 3.8%, corresponding to a yield of 48%.

Example 7

215 g (2.49 mol) of y-butyrolactone, 200 g of water, 33.7 g (0.804 mol) of lithium hydroxide monohydrate and 31.5 g of 47% aqueous trimethylamine solution (0.25 mol of trimethylamine) were placed in an autoclave for 7 hours heated to 165 ° C. The cooled reaction mixture was desalted by electrodialysis and finally evaporated to dryness. 24.5 g of residue containing 80.5% yBu-tyrobetain were obtained, corresponding to a yield of 54.3%.

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Example 8

Analogously to Example 7, 109 g (1.26 mol) of y-butyrolactone, 165 g of water and 66 g of evaporated residue of the salt solution obtained in the electrodialysis were reacted with 23.8 g (0.188 mol) of trimethylamine solution and worked up. 17.0 g of residue were obtained with 83.6% of y-butyrobetaine, corresponding to a yield of 51.8%.

Example 9

The procedure was as in Example 3, the amount of trimethylamine being 26.6 mmol and 20.5 g (0.16 mol) of lithium yhydroxybutyrate being added to the reaction mixture. The content of y-butyrobetaine in the reaction mixture after the reaction was 4.4%, corresponding to a yield of 74%.

Example 10

The procedure was as in Example 3, the amount of trimethylamine being 25.2 mmol and 8.42 g (0.1 mol) of sodium hydrogen carbonate being added to the reaction mixture. The y-butyrobetaine content of the reaction mixture after the reaction was 5.0%, corresponding to a yield of 63%.

Example 11

Analogously to Example 7, 226 g (2.6 mol) of y-butyrolactone and 157 g (1.1 mol) of sodium hydroxybutyrate were mixed with 47.1 g of aqueous trimethylamine solution (0.38 mol of trimethylamine) and 348.6 g of water for 5 hours heated to 155 ° C. 777.6 g of reaction solution with 5.6% butyrobetaine were obtained, corresponding to a yield of 80%.

Claims (8)

Claims 1. Process for the preparation of betaines of the general formula RR'R "N + A COO" I wherein R is a Ci-C22 alkyl group, R 'and R "independently of one another each a CHIU alkyl group and A is a group of the formula -CR1R2-CR3R4-CR5R6-, _crir2_cr3R4_cr5R6_cr7R6_ 0der -CR1R2-CR3R4-CR5R6-CR7R8-R1 and CR9R10- to R10 each independently represent hydrogen or a Ci-C4-alkyl group, characterized in that a lactone of the general formula O wherein A has the meaning given above, with a tertiary amine of the general formula RR'R "N III wherein R, R 'and R "have the meanings given above, is reacted in the presence of water at a temperature of 50 to 250 ° C. 2. The method according to claim 1, characterized in that the reaction is carried out at 120 to 200 ° C. 3. The method according to claim 1 or 2, characterized in that the reaction is carried out in the presence of a basic catalyst. 4. The method according to claim 3, characterized in that an alkali or alkaline earth metal hydroxide, an alkali metal carbonate or alkaline earth metal carbonate or an alkali metal bicarbonate is used as the basic catalyst. 5. The method according to claim 4, characterized in that lithium hydroxide is used as the alkali hydroxide. 4th 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 CH 687 984 A5 6. The method according to claim 3, characterized in that an alkali salt of the lactone (II) corresponding hydroxy acid is used as the basic catalyst. 7. The method according to any one of claims 1 to 6, characterized in that Y-butyrolactone is used as the lactone (II). 8. The method according to any one of claims 1 to 7, characterized in that trimethylamine is used as the amine (III). 5