Method for Recycling Methylamine Hydrochloride

Methylamine is an organic compound with a formula of CH3NH2. This colorless gas is a derivative of ammonia, but with one hydrogen atom being replaced by a methyl group. It is the simplest primary amine.  Methylamine hydrochloride synthetic pharmaceuticals, pesticides, dyes and other synthetic organic basic material having the formula:

The method of process waste byproduct methylamine hydrochloride or dimethylamine hydrochloride wastewater currently produced industrially are generally three types: 1, stripping or gas membrane Method: The aqueous solution of methylamine hydrochloride PH ^ 11, so that the vast majority of ammonia or organic amines in the presence of free ammonia in water or an organic amine may remove 99% or more to obtain an aqueous solution of ammonia or organic amines concentrated 5-20 times the volume of a by-product, which may further concentrated aqueous solution ammonia or an organic amine obtained. This method consumes a large amount lye, salt content by the waste water after the treatment is still high, increasing the difficulty of wastewater treatment; large power consumption, complex process, even though most of the amine recovery, but also for treatment of wastewater after biological processing in order to meet emission requirements. 2, the biological treatment method: waste coming methylamine hydrochloride (dissolved in water) or wastewater by anaerobic - aerobic - flocculation process, meeting the emission requirements of industrial wastewater. However, the law wastewater treatment works great, mainly a large number of methylamine hydrochloride can not be recycled, resulting in waste of raw materials. 3, Ger. Pat. No952086, Netherlands. Pat. No. 65-12169 reports the phosgene to 250 ° C to melt through methylamine hydrochloride or dimethylamine hydrochloride in a high-boiling solvent suspension of the salt into the acid chloride and reused. This method is the high reaction temperatures, strict material requirements of equipment, the reaction process is long, phosgene consumption.

Methylamine hydrochloride recycling method of Xiaohong Kong(CN) provided is the use of high pressure reaction, an organic solvent as the reaction solvent, methylamine hydrochloride with phosgene prepared methylamino chloride. The organic solvent is 1,1-dichloroethane, 1,2-dichloroethane, chloroform, toluene, xylene any one of an amount of methylamine hydrochloride in an amount of 2-5 molar. 5 times; 1. phosgene in an amount of 01-15 times the molar amount of monomethylamine hydrochloride; reaction temperature is 80 ° C~150 ° C, the reaction time is 4 to 8 hours, a reaction pressure of 1.6~3.0 MPa.

Reaction Scheme:

CH3NH2HCl + COCl2> CH3NHCOCI + 2HC1

The specific steps of the Kong’s present invention is a light gas containing the slag and methylamine hydrochloride liquefied organic solvent metered a stirred autoclave, the reaction pressure is 1.6~3.0 MPa, organic solvent molar 2-5 in an amount of 5 times the molar quantity of methylamine hydrochloride, a molar amount of phosgene 1. 01-1. 5-fold molar amount of methylamine hydrochloride, the reaction 4 at 80 ° C ~50 ° C temperature 8 hours, then the reaction was cooled to room temperature and filtered to give the filtrate methylamino chloride. Methylamine hydrochloride pass reaction yield> 90%. The filtrate was stripped to the column directly after the removal of excess phosgene gas. Removal of condensed phosgene after recycling, hydrochloric acid gas absorption into the exhaust system.

The advantages of the Kong’s present invention are: the use of an organic solvent to make the reaction solvent, phosgene and methylamine hydrochloride at high pressure in a urethane prepared by reacting carboxylic acid chloride, simple process, mild reaction conditions and high yield, used industrial organic solvents adapt claim methylamine hydrochloride salt was treated directly recycled, significantly reduce the energy consumption and waste emissions, good environmental benefits. 

References

[1]Xiaohong Kong, Ping Li, Qianzheng Xiong, et al. Method for recycling methylamine hydrochloride.China Patent No.101891652A
[2] Shangwu Chen. N-methylcarbamoyl chloride synthesis ratio study [J], 《Hubei Chemical Industry》, December 2001 (2001-12-31), no. 1, 31,pages 34 – 35.

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