CN101074480A - Method for crystallizing L-cysteine muriate high-purity crystal - Google Patents

Abstract

A method for crystallizing L-beta-mercaptoalanine high-purity crystal is carried out by preparing L-beta-mercaptoalanine cathode electrolytic bath liquid by electrolyzing L-cystine, decompress concentrating for electrolytic bath liquid at 70-80 degree, reaching L-beta-mercaptoalanine equivalent concentration in concentrate to 6-8N, reaching hydrochloric acid equivalent concentration 1.2-2 times of L-beta-mercaptoalanine, agitating at 1-6 degree, lowering temperature to 8-12 degree, laying aside and crystallizing. The crystal grain size is coarse, uniform, transparent, net and diamond, the length is 4-5 mm, and width and thickness are 2-3 mm. It has 5 times re-crystallization and better purity.

Description

The crystallization method of L-cysteine muriate high-purity crystal

Technical field

The present invention relates to the manufacture method of L-cysteine hydrochloride, specifically is the crystallization method that crystallization obtains L-halfcystine high-purity crystal in the cell liquid of electrolysis L-Gelucystine acquisition L-cysteine hydrochloride.

Background technology

The L-cysteine hydrochloride has the effect of the stasis of blood of reducing phlegm mainly as the medicine of bronchitis, radiation injury, and the poisoning that is caused by vinyl cyanide and aromatic acid etc. is had detoxification.Fields such as simultaneously fresh-keeping at bread fermentation, fruit juice, aminoacids complex, enhancing food, day chemical industry and fodder additives are with a wide range of applications.

The L-cysteine hydrochloride mainly exists with the form of monohydrate.L-cysteine hydrochloride molecular formula is C₃H₇NO₂SHClH₂O, molecular weight is: 175.61, structural formula is as follows:

L-cysteine hydrochloride preparation method adopts L-Gelucystine electrolytic reduction technology substantially, and the L-Gelucystine drops in the hydrochloric acid soln and carries out electrolysis, and after electrolysis finished, the catholyte tank liquor obtained L-cysteine hydrochloride crystal through concentrated, crystallization:

This technology is mature on the whole at present, but mother liquor is after repeatedly circulation repeats crystallization after the crystallization, also has only 1: 1.34 by the L-Gelucystine to L-cysteine hydrochloride total conversion rate, differ bigger at 1: 1.46 with theoretical yield, mother liquor repeatedly circulates, and then crystallized product purity and clarity have obvious decline in crystallization, but repeatedly the waste liquid after the crystallization still contains a large amount of callable L-halfcystines, thus people research focus on improving transformation efficiency, the crystallization purifying of L-halfcystine is not appeared in the newspapers yet.Because existing crystallization condition is unreasonable; the L-cysteine hydrochloride crystal that the cell liquid Crystallization Separation obtains is Powdered or tiny needle-like; often be mixed with small amount of impurities in the crystal, therefore need follow-up purifying technique just can obtain high-purity L-cysteine hydrochloride crystal.

Summary of the invention

The object of the present invention is to provide a kind of crystallization method of L-cysteine muriate high-purity crystal, can reduce follow-up recrystallization purifying process thus.

The present invention utilizes electrolysis L-Gelucystine to prepare the catholyte tank liquor of L-halfcystine, after electrolysis finishes, the cell liquid concentrating under reduced pressure, 70～80 ℃ of thickening temperatures, the equivalent concentration 6～8N of L-halfcystine in the concentrated solution after concentrating, the equivalent concentration of regulating hydrochloric acid in the concentrated solution is 1.2～2 times of L-halfcystine, stir cooling down, speed is 1～6 ℃/hour, stops cooling after being cooled to 8～12 ℃ and stirs, left standstill crystallization 6～30 hours, filtration, washing obtain crystal.

Described crystallisation process cooling rate is preferably 2～4 ℃/hour, and leaving standstill crystallization time is 8～12 hours, preferred 5～15 rev/mins of temperature-fall period stirring velocity.。

The L-cysteine hydrochloride crystal size that contains a crystal water that the present invention obtains is thick evenly, 4～5 millimeters of length, 2～3 millimeters of width and thickness, the water chestnut column, glittering and translucent, be difficult for sneaking into impurity in the crystal, mother liquor repeats crystallization through five similarity conditions after the crystallization, crystalline form and purity remain unchanged, and purity reaches more than 99.5%.

Embodiment

Embodiment 1

With hydrochloric acid and pure water compound concentration is 1.6 tons of the hydrochloric acid solns of 2.0N, drops into 350 kilograms of L-Gelucystines, and dissolving is finished the back and added activated carbon by gross weight 1%, stirs decolouring in 40 minutes, filtration, and filtrate pumps into cathode can and carries out cyclic electrolysis.

Electrolytic condition is: voltage 36V, anolyte equivalent concentration is controlled at 2.5N, about 16 hours of electrolysis time.

After electrolysis finishes, filter, filtrate pumps into concentration tank and carries out concentrating under reduced pressure, concentration tank vacuum tightness 0.09MPa, 75 ℃ stirring is concentrated after 10 hours down, check concentrated solution concentration, finish to concentrate check concentration of hydrochloric acid, hydrochloric acid equivalent concentration 10N during L-halfcystine equivalent concentration 8N.Under 10 rev/mins stirring velocity, progressively lower the temperature with 4 ℃/hour cooling rate then, insulation was 1 hour after temperature dropped to 10 ℃.Centrifuging, with the washing of a small amount of frozen water, oven dry obtains epigranular, the water chestnut column crystallization that 4～5 millimeters of length, width and height are 2～3 millimeters, outward appearance is glittering and translucent.Mother liquor concentrating under five identical conditions, crystallization obtain same water chestnut column crystallization.Product is with charging into N₂Bag film packing, shading is preserved.The product sampling analysis, detected result is as follows:

Project	Detected result
		Outward appearance	The translucent crystallization of white, 2～3 millimeters of 4～5 millimeters of length, width, height, water chestnut column
Content	99.7％
		The pH value	1.8
Specific rotatory power, [α]D20	+6.2°
		Solubility test	Water white transparency
Clarity test	98.7％
		Chlorine (Cl)	20.02％
Ammonium salt (NH4)	0.01％
		Vitriol (SO4)	0.01％
Iron (Fe)	4.0ppm
		Heavy metal (Pb)	2.0ppm
Arsenic (As2O3)	0.6ppm
		Other amino acid	Climb the plate immaculate
Weight loss on drying	10.0％
		Ignition residue	0.08％

Embodiment 2

With hydrochloric acid and pure water compound concentration is 1.6 tons of the hydrochloric acid solns of 2.3N, drops into 350 kilograms of L-Gelucystines, and dissolving is finished the back and added activated carbon by gross weight 1%, stirs decolouring in 40 minutes, filtration, and filtrate pumps into cathode can and carries out cyclic electrolysis.

Electrolytic condition is: voltage 36V, anolyte equivalent concentration is controlled at 3.0N, about 16 hours of electrolysis time.

After electrolysis finishes, filter, filtrate pumps into concentration tank and carries out concentrating under reduced pressure, concentration tank vacuum tightness 0.09MPa, 80 ℃ stirring is concentrated after 10 hours down, check concentrated solution concentration, finish during halfcystine equivalent concentration 6N to concentrate, the check concentration of hydrochloric acid, hydrochloric acid equivalent concentration is 8N.Under 10 rev/mins stirring velocity, progressively lower the temperature with 2 ℃/hour cooling rate then, insulation was 1 hour after temperature dropped to 10 ℃.Centrifuging, with the washing of a small amount of frozen water, oven dry obtains epigranular, the water chestnut column crystallization of 4～5 millimeters of length, 2～3 millimeters of width, outward appearance is glittering and translucent.Mother liquor concentrating under five identical conditions, crystallization obtain same water chestnut column crystallization.Product is with charging into N₂Bag film packing, shading is preserved.The product sampling analysis, detected result is as follows:

Project	Detected result
		Outward appearance	The translucent crystallization of white, 2～3 millimeters of 4～5 millimeters of length, width, height, water chestnut column
Content	99.9％
		The pH value	1.7
Specific rotatory power, [α]D20	+6.4°
		Solubility test	Water white transparency
Clarity test	98.9％
		Chlorine (Cl)	20.01％
Ammonium salt (NH4)	0.01％
		Vitriol (SO4)	0.01％
Iron (Fe)	5.0ppm
		Heavy metal (Pb)	2.0ppm
Arsenic (As2O3)	0.7ppm
		Other amino acid	Climb the plate immaculate
Weight loss on drying	9.4％
		Ignition residue	0.05％

Claims (4)

1. the crystallization method of a L-cysteine muriate high-purity crystal, utilize electrolysis L-Gelucystine to prepare the catholyte tank liquor of L-halfcystine, after electrolysis finishes, the cell liquid concentrating under reduced pressure, it is characterized in that, 70～80 ℃ of described thickening temperatures, concentrate the equivalent concentration 6～8N of L-halfcystine in the concentrated solution of back, the equivalent concentration of regulating hydrochloric acid in the concentrated solution is 1.2～2 times of L-halfcystine, stir cooling down, speed is 1～6 ℃/hour, stops cooling after being cooled to 8～12 ℃ and stirs, left standstill crystallization 6～30 hours, filtration, washing obtain crystal.

2. according to the crystallization method of the described L-cysteine muriate high-purity crystal of claim 1, it is characterized in that described crystallisation process cooling rate is 2～4 ℃/hour.

3. according to the crystallization method of the described L-cysteine muriate high-purity crystal of claim 1, it is characterized in that, describedly left standstill crystallization time 8～12 hours.

4. according to the crystallization method of the described L-cysteine muriate high-purity crystal of claim 1, it is characterized in that 5～15 rev/mins of described temperature-fall period stirring velocitys.