Sodium Hydroxide → (-)-Cystine

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Reaction Steps

100 grams of L-cystine dihydrochloride were dissolved in 500 ml of water. The solution was adjusted to pH 3 by the addition of a concentrated aqueous solution of sodium hydroxide. As a result of this, the L-cystine separated out. The yield was 74 grams, corresponding to 94% based on the L-cystine dihydrochloride added. The L-cystine in a 5 percent solution in 1 N aqueous hydrochloric acid had a specific rotation of -217°. According to thin layer chromatography and column chromatography examination it was free from impurities.

Provenance & Evidence