BE719104A - - Google Patents

Description

  

  The present invention relates to a process for the preparation of esters of carboxylic acids and

  
 <EMI ID = 1.1>

  
by reaction with the alkali salt of a carboxylic acid in the corresponding ester of p-formylcrotyl alcohol.

  
However, it has been found that esters of carboxylic acids and p-formylcrotyl alcohol can be prepared in a simple manner, when esters are transposed from carboxylic acids and from 2-formyl-2-hydroxy-butene. - (3) or

  
 <EMI ID = 2.1>

  
cuprous or cupric compounds or their mixture and that the products thus obtained are hydrolyzed, if necessary.

  
 <EMI ID = 3.1>

  
to care about . by way of example, the reaction equation below: '

  

 <EMI ID = 4.1>


  
While giving good yields, the new pro

  
 <EMI ID = 5.1>

  
In general, the starting materials for the process of the invention are accessible in a simpler manner and with better yields than the starting materials for the process of the invention.

  
 <EMI ID = 6.1> low molecular weight alkoxy or halogen atoms, for example chlorine or bromine. Preference is given to using starting substances, the ester group of which is derived from aliphatic carboxylic acids with 1 - 4 carbon atoms, as examples of carboxylic acids forming the basis of the ester group; we will mention hexahydrobenzoic acid, acetic acid,

  
 <EMI ID = 7.1>

  
zolque, palmitic acid.

  
Esters can be used as starting substances

  
 <EMI ID = 8.1>

  
of its acetal or acylate, the acetals preferably being used ...

  
 <EMI ID = 9.1>

  
Aliphatic cools of 1, .- 4 carbon atoms, such as methyl alcohol, ethyl alcohol, isopropyl alcohol. As

  
 <EMI ID = 10.1>

  
Suitable as catalysts for the conversion of metallic copper as well as copper compounds or

  
 <EMI ID = 11.1>

  
copper can be organic as well as inorganic, the nature of the anion in the copper salts not being critical.

  
Metallic copper can be used by. example in form

  
 <EMI ID = 12.1>

  
powder. As suitable copper or cupric compounds, there may be mentioned, for example, cuprous chloride, copper bromide.

  
 <EMI ID = 13.1>

  
'acetate, oxide or cupric hydroxide. We can put in. uses the catalysts as they are or else applied to an inert support. The amount of catalyst can vary between

  
wide limits. In general, the catalyst, calculated as copper, is used in amounts between 0.005 and

  
 <EMI ID = 14.1>

  
starting substance.

  
For the reaction. we usually choose temples "

  
 <EMI ID = 15.1>

  
already that decomposition products are formed. The reaction is generally carried out under atmospheric pressure. However, it is also possible to operate under increased pressure, for example when the reaction is carried out at a temperature above the boiling point of the reaction mixture, or well under reduced pressure, such as 700 mm Hg. The process according to the invention can be carried out both batchwise and continuously.

  
 <EMI ID = 16.1>

  
the starting substances as they are or with inert solvents. As preferred solvents, mention will be made of hy-;

  
 <EMI ID = 17.1>

  
tick or cyclic, low molecular weight aliphatic carboxylic acids, amides, In this context, for example, n-hexane, n-octane, hydrocarbons from petroleum, which have for example a zone of boiling between 80 and 150 * This cyclohexane, benzene,

  
 <EMI ID = 18.1>

  
tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, formic acid, acetic acid, N-methylpyrrolidone, dimethylformamide.

  
When carboxylic acid esters and 2-formyl-2-hydroxy-butene (") are used as starting materials, immediately after conversion, esters are obtained.

  
 <EMI ID = 19.1>

  
starting with the corresponding acetals or acylates, acetals or acylates are obtained as transposition products

  
 <EMI ID = 20.1>

  
lique, which are then transformed into the final products by hydrolysis in a manner known per se. For this purpose, the acetals or the transposed acylates can be isolated and then hydrolyzed by a second operation. It is, however, advantageous to convert the transposed acetals or acylates into the final products in the same reaction vessel, without isolating them.

  
For hydrolysis, for example dilute aqueous mineral acids, such as hydrochloric acids, can be isolated.

  
 <EMI ID = 21.1>

  
nitric acid in a concentration of 1% by weight, for example. The hydrolysis is however advantageously carried out "in,

  
 <EMI ID = 22.1>

  
Depending on the temperature, the transposition reaction generally lasts 2 to 6 hours. Depending on the temperature and the pH of the reaction mixture, the hydrolysis of the transposed acetals or acylates generally takes 0.5 to 2 hours,

  
The process can be carried out, for example, so as to heat to the drafting temperature in a stirred vessel the starting substance together with the catalyst, optionally in an inert solvent. Once the transposition is complete, it is optionally subjected to hydrolysis. The hydrolysis is carried out, for example, so as to add to the reaction mixture thus obtained, in the same reaction recrient, for example water, and that the mixture is maintained for a period of time.

  
 <EMI ID = 23.1>

  
drolysis. The ester of the carboxylic acid and α-formyl-crotyl alcohol, each time contained in the mixture, is subjected to the post-treatment by purifying by distillation or by crystallization.

  
 <EMI ID = 24.1>

  
The parts shown in the following examples are by weight.

  
 <EMI ID = 25.1>

 

Claims (1)

Example 2 <EMI ID = 26.1> glacial acetic acid and 0.5 part of copper acetate. Then 200 parts of water are added and the mixture is abandoned. <EMI ID = 27.1> 10 parts of copper powder. The copper powder is then filtered off from the reaction mixture and washed with a little chloroform. The copper powder is advantageously reused for the reaction. The combined filtrates are subjected to the post-treatment described in Example 1. 53 g are obtained. <EMI ID = 28.1> metallic copper *, cuprous or cupric compounds or their mixtures, and that the products may be hydrolyzed in this way obtained,