Clean Production Technology And Industrial Application Of Acetyl L-Carnitine Hydrochloride

Acetyl L-carnitine hydrochloride,as a naturally occurring substance in the body,has important physiological functions in protecting nerves,promoting nerve function,protecting male reproductive health,preventing Alzheimer’s disease,etc.It is currently widely used in food,medicine and other fields,but with the continuous increase of the product market and the gradual improvement of people’s requirements for product safety,The demand for L-carnitine and acetyl L-carnitine hydrochloride with high product quality is gradually increasing.Firstly,the existing process of L-carnitine was analyzed,and the synthetic route combining biological and chemical methods was adopted to avoid the use of toxic cyanide in pure chemical synthesis.Ethyl 4-chloroacetoacetate was used as the substrate to catalyze the production of(R)-4-chloro-3-hydroxybutyrate by carbonyl reductase.During the catalytic process,the substrate concentration reached 150 g/L,and the conversion rate reached 98.5%.Ethyl(R)-4-chloro-3-hydroxybutyrate was obtained by extraction,concentration and distillation,and the yield reached more than 80%.Subsequently,L-carnitine was obtained by trimethylamine ammoniation reaction.The product was purified by resin,and the yield was 80%,The product conforms to national standards.In this paper,a systematic study was carried out aiming at the shortcomings of low product yield and difficult control of key impurities in the existing acylation process of L-carnitine.At the same time,an industrial production route was designed based on the actual production situation,which has practical application value.The acylation effect of L-carnitine in different acylation systems was investigated.Because of the special structure of L-carnitine hydroxyl group,acetic anhydride can acetylate it in the water phase and acetic acid phase,but the reaction speed is slow and the conversion rate is very low,which is not suitable for industrialization.In the acylation system of acetic acid/acetyl chloride,the acylation effect is obvious,but impurities are also generated.The production process is explored and continuously optimized.Throμgh the design of single factor experiments such as material ratio,reaction time and post-treatment solvent,the various factors affecting the reaction were studied,and finally the reaction conditions with the molar ratio of acetyl chloride and L-carnitine of 1.2:1 and the reaction temperature of40-45 ℃ were determined.The post-treatment used dichloromethane to remove the L-carnitine and acetyl chloride that did not react completely,while removing other impurities to obtain a high quality product.Due to the high solubility of the product in acetic acid,it cannot be recovered by vacuum distillation crystallization.we developed a process of mother liquor application.Through continuous mother liquor application,we controlled the key indicators in the product,the quality yield of the product relative to L-carnitine reached 121%,which is higher than the level reported in the current literature,and has more industrialization potential and cost advantages.Through the comparative study of the enterprise standards of different production enterprises,the biggest difference at present is the control of impurities in the product.It is necessary to conduct a systematic study on the nature of impurities to further determine the product quality standards.Acetyl L-carnitine hydrochloride is mainly used in food-related fields,and its production needs to meet the relevant standard requirements.We have analyzed the key points of its production,formulated the production process procedures,At the same time,the industrialization design and application of the workshop are preliminarily explored.