JPS59216865A - Drying of cysteine hydrochloride hydrate - Google Patents

Abstract

PURPOSE:To obtain purified crystal of cysteine hydrochloride hydrate useful as drugs, foods, cosmetic, etc. simply, by filtering an aqueous solution of hydrochloric acid containing crude crysteine by a centrifugal dryer, drying it. CONSTITUTION:An aqueous solution of hydrochloric acid containing crude cysteine is recrystallized to give slurry of purified cysteine hydrochloride hydrate, which is filtered by a batch type centrifugal dryer, it is not taken out of the system, and dried air at 0-40 deg.C, preferably 20-40 deg.C is forcedly introduced from nozzles attached to the dryer into the dryer successively, and dehydration and drying are carried out simultaneously, to give the desired substance. The centrifugal effect during dehydration is preferably at about 300-1,000 G, and a plastic, rubber, or a specific metal having hydrochloric acid resistance is used as a material for the centrifugal dryer. The crystal of purified cysteine hydrochloride can be directly processed into products.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for drying cysteine hydrochloride hydrate crystals. More specifically, when crystallizing crystals from an aqueous hydrochloric acid solution containing crude cysteine, filtering and drying the slurry, the slurry is filtered using a centrifugal dehydrator, and during dehydration, air is blown through the nozzle of the equipment and dried at the same time. This invention relates to a method for drying cysteine hydrochloride hydrate.

The industrial method for producing cysteine or its oxidation product, cysteine, is to hydrolyze and extract cysteine contained in human hair, body hair, etc., and purify and isolate cysteine by electrolytic reduction in the presence of hydrochloric acid. How to do it, β-
Reacting halogenoalanine with a compound having a sulfur atom to form an ester salt, which is then hydrolyzed in the presence of hydrochloric acid.
Methods for producing cysteine using synthetic methods are known◇
Cysteine is usually isolated as a crystal in the form of a hydrochloride-hydrate and is commercially available as a commercial product.

The reason for this is that compared to free cystine, oxidation to cystine is slow and storage stability is good, and it is usually isolated from an aqueous hydrochloric acid solution as described above. For this reason, there are limitations in drying cysteine in order to maintain the crystalline form of hydrochloride-hydrate.

In other words, there is a limit to the drying temperature because cysteine melts at temperatures above 50"C, resulting in a drying temperature of 11.1"C.
Preferably 0°C! It is necessary to carry out the process at 20 to 40°C, and if you try to dry under reduced pressure to shorten the drying time, some of the crystallization water will come out, which will cause quality control problems. , which is usually carried out under normal pressure. Furthermore, the issue of particles in the dryer and attached equipment is also important.
Metals such as iron and SUS cannot be used because they are corroded by hydrochloric acid, and it is necessary to select plastic, rubber, or a special metal that is resistant to hydrochloric acid. (3) Dry exhaust gas contains wet hydrochloric acid gas and has a sulfur odor, so it cannot be released into the atmosphere as it is, and requires exhaust gas treatment measures such as absorption in an aqueous alkaline solution.

As mentioned above, Cystine's drying equipment has various limitations when it comes to industrial scale, and has the drawback of requiring a large amount of equipment investment.

The method of the present invention does not require a large amount of equipment costs, such as installing a new drying process using hydrochloric acid-resistant scales, as in the conventional method, from a slurry containing cysteine hydrochloride group-hydrate crystals. Cystine hydrochloride group hydrate crystals containing almost no attached water can be obtained by a simple method of blowing dry air during dehydration and isolation using a centrifuge.

In the present invention, it is preferable to use a centrifugal dehydrator as a Fail and "U" dryer for cysteine, and carry out the process in a patch method.In other words, it is preferable to use a centrifugal dehydrator as a cysteine fail and "U" dryer, and carry out the process in a patch manner. This slurry is filtered through a batch-type centrifugal dehydrator, and then air is forcibly blown through a nozzle installed in the equipment without taking it out of the system. As a centrifugal dehydrator that also performs drying by creating air-drying conditions and dehydrating for a desired time, a hydrochloric acid-resistant, for example, a rubber-lined vertical centrifuge is suitable.

The centrifugal effect during dehydration should be as large as possible, but it is 300 to 10
Approximately 0OG is sufficient.

Further, the amount of air blown from the nozzle of the centrifugal separator during dehydration is not particularly limited, and is determined by the size of the centrifugal separator used, the throughput, and the processing time. There is no particular restriction on the temperature of the air as long as it is below the melting temperature of cysteine, and air at room temperature is fine, but dehumidified dry air at 20 to 40° C. is preferable. Also, as in the filtration step, the dry exhaust gas is led to the exhaust gas cleaning device from the F liquid outlet of the centrifuge and is treated therein.

The crystals of refined cysteine hydrochloride hydrate, which have been dried by blowing air for a desired period of time, can be scraped off with a scraping device and shipped as a product simply by being packaged in bags.

As described above, according to the present invention, p-perdrying can be easily performed and commercialized using a single centrifugal dehydrator without installing a cysteine filter and a dryer separately, and the present invention The effects of this method are significant.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples.

(6) Example Reaction product of β-chloralanine and 1-lithiocarbonic acid, mono(amine hydroxyethyl phthiocarbonic ester) obtained by hydrolysis in an aqueous solution of hydrochloric acid, coarse nails, L-cysteine 9% in aqueous solution 70 containing 5 kg of hydrochloride hydrate:
While stirring with a crystallizer made of 1001 glass lining,
The mixture was cooled to 5°C to precipitate fine cysteine. This slurry was passed through a rubber-lined vertical centrifuge (Tanabe Iron Works size 2).
Feed a 4-inch tube and perform filtration.Next, the rotation speed during dehydration was set to 170 Orpm (centrifugal effect: 700 GJ).
Then, dry air (temperature 28D,
Dehydration was carried out for 30 minutes while forcibly blowing in water (dew point -40°C) at a flow rate of 300 l/f+.

[Theoretical value [crystal water content] ＼＼wj%].

In addition, the drying loss is measured using a 1g sample in a vacuum desiccator (vacuum).
It was dried with On'L+y+J (g or less, silica gel) for 24 hours, and the loss on drying was measured according to the well-known [General Rules for Cosmetic Raw Materials Standards]. Moreover, the purity was measured by titrimetric analysis of the dried product.

From the above measurement results, it was found that the adhering water content was only 01 wt% compared to the theoretical value, and the cysteine hydrochloride hydrate taken out from the centrifuge was almost completely dried.

Comparative Example Crystallization and filtration using a centrifuge were carried out under exactly the same conditions as in the Example, except that the dehydration was carried out for 30 minutes without blowing air during the dehydration. The purity of the crystals was 98.8 wt%, and the loss on drying was 11.8 wt%.

In addition, the crystals were wet and the hydrochloric acid was left behind.

After continuing to extend the dehydration time and dehydrating for a total of 3 #s, the loss on drying] 1. Although it decreased to Qwt%, the hydrochloric acid component did not disappear.

Claims (1)

[Claims] 1. A slurry containing cysteine hydrochloride hydrate obtained by crystallizing two crystals from an aqueous hydrochloric acid solution containing crude cysteine is filtered and dried to obtain a crystal of cysteine hydrochloride hydrate. A method for drying cysteine hydrochloride hydrate, characterized in that when the slurry is filtered and dehydrated using a centrifugal dehydrator, air is blown into the dehydrator to perform dehydration and drying simultaneously. 2. The method according to claim 1, wherein the air blown in during dehydration is dry air at a temperature of 20 to 40°C.