Preparation Of Amide Substance By Ammonia Exchange Of Dimethyl Oxalate And Its Application

In recent years,China's coal chemical industry has developed rapidly.Coal-based ethylene glycol has become an important project in the development of national coal chemical industry.The demand for ethylene glycol in China will also gradually increase.However,from a global perspective,ethylene glycol has experienced overcapacity trend.Therefore,this paper uses dimethyl oxalate,an intermediate product of coal-based ethylene glycol,to prepare amides such as oxamide and polyoxalate,and explores the sustained-release properties of oxamide and the solvent resistance of polyoxalate.Provide new ways to reduce the risk of excess ethylene glycol overcapacity.In this paper,the synthetic route of amide compounds prepared by ammonia exchange reaction of dimethyl oxalate was studied.The problems in the synthesis of oxalic acid and polyoxalate were analyzed,and the preparation process of oxamide and polyoxalate was explored and optimized.The added value of coal-based ethylene glycol by-products has laid a solid foundation for the final industrialization of the products.In this paper,oxamide was continuously produced by tubular reactor using dimethyl oxalate as raw material,and the prepared oxamide was characterized by infrared and nuclear magnetic properties.The effects of solvent,reaction temperature,reaction time and ammonia flow rate on the conversion of dimethyl oxalate were investigated.The process conditions for the preparation of oxamide by dimethyl oxalate were determined by experiment: methanol as reaction solvent,normal pressure at 60?,ammonia flow rate of 4 L/min,and 4 h of cyclic reaction,the final conversion rate of dimethyl oxalate was 98.70%.In order to prepare a slow-release fertilizer oxaamide granule which is convenient to use and has stable performance,the powdered oxamide and the auxiliary agent are mixed in a certain ratio.The best process formula was determined by experimental screening: 80% oxamide(raw material),3% kaolin(carrier),6% sodium dodecylbenzene sulfonate(wetting agent),5% calcium lignin sulfonate(dispersant),5% sodium sulfate(disintegrant),1% sodium carboxymethylcellulose(adhesive).The fertilizer yield performance of the finally obtained oxamide particles was tested.The results show that the finally obtained product oxalyl granules have good sustained release properties and promote crop yield increase.Dimethyl oxalate and hexamethylenediamine were added to a three-necked flask,and reacted at 50? for 2 h to obtain a polyoxalate 6,2 prepolymer.Finally,polyoxalate 6,2 were prepared in a micro pressure reactor.The effects of raw material ratio,reaction temperature,reaction time and stirring rate on the synthesis reaction of polyoxalate 6 and 2 were investigated,and the optimal reaction process was obtained through experimental screening: the excess mole fraction of hexamethylenediamine was 4%,polymerization The temperature was 340?,the polymerization time was 3 h,and the stirring rate was 400 r/min.Finally,the product polyoxalate 6,2 was characterized by infrared.The preparation technology of polyoxalate 6,2 was explored and optimized,and the added value of coal glycol by-products was added,which laid a solid foundation for the final industrialization of the product.