CH464197A - Process for the direct preparation of free esters of B-pyridinecarboxylic acid with amino alcohols - Google Patents

Description

  

  
 



  Process for the direct preparation of free esters of B-pyridinecarboxylic acid with amino alcohols
The preparation of esters of β-pyridinecarboxylic acid with amino alcohols by a known method, namely by treating equivalent amounts of the amino alcohols with nicotinoyl chloride hydrochloride, primarily gives the hydrochlorides of the esters. The preparation of the free esters must therefore take place in two stages. In addition, the yield of the compounds prepared by this two-stage process is unsatisfactory.



   It has now been found that the free esters can be obtained directly, and this in a higher degree of purity and in a better yield, if the amino alcohol to be esterified is suspended in a reaction mixture consisting of equivalent amounts of oxalyl chloride and alkali metal salt of ß-pyridine carboxylic acid an organic solvent such as benzene - can react. After cooling and washing the organic phase with soda solution and subsequent drying and filtration of the organic phase, the solvent can be distilled off and the resulting free ester can be purified by distillation in a high vacuum.



   The preparation of the dimethylaminoethyl ester of β-pyridinecarboxylic acid is given as an example of the new process, but other amino alcohols of the general formula can also be used by this method
EMI1.1
 where x = 0 or 1 and Rt is an alkyl radical and R2 = H or CH5, esterify with β-pyridinecarboxylic acid.



   example
15 g (93 mmol) of potassium nicotinate are suspended in 80 ml of absolute benzene. At a temperature of 0 C, 11.8 g (93 mmol) of oxalyl chloride in 30 ml of absolute benzene are added dropwise. The temperature is now slowly increased to about 40 ° C. and the reaction mixture is left at this temperature for 20 minutes. Then 10.8 g (121 mmol) of dimethylaminoethanol are added to the reaction mixture and the mixture is heated to 600 ° C. for 2 hours. After cooling, the benzene solution is washed twice with 2N soda solution, the aqueous phase is extracted again with benzene and the combined dried benzene extracts, filtered and evaporated. The oily residue is then distilled in a high vacuum.

   The nicotinic acid N, N-dimethylaminoethyl ester boils at 0.5 mm at 960 ° C. The yield is 92%, while the yield for the same compound, prepared by the already known process, is only 34%.



   PATENT CLAIM
Process for the direct preparation of the free ss pyridine carboxylic acid esters with amino alcohols of the general formula
EMI1.2
 where x = 0 or 1 and Rt is an alkyl radical and R2 = H or CH3, characterized in that the amino alcohol to be esterified is reacted with the reaction mixture consisting of equivalent amounts of oxalyl chloride and alkali metal salt of fi-pyridinecarboxylic acid - suspended in an organic solvent leaves.



   SUBClaim
Method according to claim, characterized in that benzene is used as the organic solvent.

** WARNING ** End of DESC field could overlap beginning of CLMS **.



   

 

Claims (1)

** WARNING ** Beginning of CLMS field could overlap end of DESC **. Process for the direct preparation of free esters of B-pyridinecarboxylic acid with amino alcohols The preparation of esters of β-pyridinecarboxylic acid with amino alcohols by a known method, namely by treating equivalent amounts of the amino alcohols with nicotinoyl chloride hydrochloride, primarily gives the hydrochlorides of the esters. The preparation of the free esters must therefore take place in two stages. In addition, the yield of the compounds prepared by this two-stage process is unsatisfactory. It has now been found that the free esters can be obtained directly, and this in a higher degree of purity and in a better yield, if the amino alcohol to be esterified is suspended in a reaction mixture consisting of equivalent amounts of oxalyl chloride and alkali metal salt of ß-pyridine carboxylic acid an organic solvent such as benzene - can react. After cooling and washing the organic phase with soda solution and subsequent drying and filtration of the organic phase, the solvent can be distilled off and the resulting free ester can be purified by distillation in a high vacuum. The preparation of the dimethylaminoethyl ester of β-pyridinecarboxylic acid is given as an example of the new process, but other amino alcohols of the general formula can also be used by this method EMI1.1 where x = 0 or 1 and Rt is an alkyl radical and R2 = H or CH5, esterify with β-pyridinecarboxylic acid. example 15 g (93 mmol) of potassium nicotinate are suspended in 80 ml of absolute benzene. At a temperature of 0 C, 11.8 g (93 mmol) of oxalyl chloride in 30 ml of absolute benzene are added dropwise. The temperature is now slowly increased to about 40 ° C. and the reaction mixture is left at this temperature for 20 minutes. Then 10.8 g (121 mmol) of dimethylaminoethanol are added to the reaction mixture and the mixture is heated to 600 ° C. for 2 hours. After cooling, the benzene solution is washed twice with 2N soda solution, the aqueous phase is extracted again with benzene and the combined dried benzene extracts, filtered and evaporated. The oily residue is then distilled in a high vacuum. The nicotinic acid N, N-dimethylaminoethyl ester boils at 0.5 mm at 960 ° C. The yield is 92%, while the yield for the same compound, prepared by the already known process, is only 34%. PATENT CLAIM Process for the direct preparation of the free ss pyridine carboxylic acid esters with amino alcohols of the general formula EMI1.2 where x = 0 or 1 and Rt is an alkyl radical and R2 = H or CH3, characterized in that the amino alcohol to be esterified is reacted with the reaction mixture consisting of equivalent amounts of oxalyl chloride and alkali metal salt of fi-pyridinecarboxylic acid - suspended in an organic solvent leaves. SUBClaim Method according to claim, characterized in that benzene is used as the organic solvent.