Reichstein

Rehm-Weller equation Reichert cone Reich process Reichstein approach... 

Most current industrial vitamin C production is based on the efficient second synthesis developed by Reichstein and Grbssner in 1934 (15). Various attempts to develop a superior, more economical L-ascorbic acid process have been reported since 1934. These approaches, which have met with htde success, ate summarized in Crawford s comprehensive review (46). Currently, all chemical syntheses of vitamin C involve modifications of the Reichstein and Grbssner approach (Fig. 5). In the first step, D-glucose (4) is catalytically (Ni-catalyst) hydrogenated to D-sorbitol (20). Oxidation to L-sotbose (21) occurs microhiologicaRy with The isolated L-sotbose is reacted with acetone and sulfuric acid to yield 2,3 4,6 diacetone-L-sorbose,... 

Fermentation. Much time and effort has been spent in undertaking to find fermentation processes for vitamin C (47). One such approach is now practiced on an industrial scale, primarily in China. It is not certain, however, whether these processes will ultimately supplant the optimized Reichstein synthesis. One important problem is the instabiUty of ascorbic acid in water in the presence of oxygen it is thus highly unlikely that direct fermentation to ascorbic acid will be economically viable. The successful approaches to date involve fermentative preparation of an intermediate, which is then converted chemically to ascorbic acid. 

L-Sorhose to 2-KGA Fermentation. In China, a variant of the Reichstein-Grbssner synthesis has been developed on an industrial scale (see Fig. 5). L-Sorbose is oxidized direcdy to 2-ketogulonic acid (2-KGA) (24) in a mixed culture fermentation step (48). Acid-catalyzed lactonization and enolization of 2-KGA produces L-ascorbic acid (1). 

Adrenosterone (Reichstein s G) [382-45-6] M 300.4, m 220-224 . Crystd from EtOH. Can be sublimed under high vacuum. 

Detection and result The chromatogram was freed from mobile phase and evenly sprayed with reagent solution. After a short time at room temperature violet-colored chromatogram zones appeared for the corticosteroids tetrahydrocortisol hRf 10-15), tetrahydrocortisone (hR( 15 — 20), prednisolone hRf 15-20), hydrocortisone (hR( 20 — 25), prednisone hRf 30 — 35), cortisone hRf 35 — 40), corticosterone hRf 45 — 50), cortexolone (Reichstein S., hRf 50 — 55), 11-dehydro-corticosterone hRf 60 — 65), 11-desoxycorticosterone hRf 75 — 80). 

Ahl and Reichstein have pointed out that though it is certain that the structure of emetine includes one, and possibly two, 6 7-dimethoxy-tetrahydroisoquinoline nuclei, the suggestions so far made as to the nature of the rest of the molecule are speculative. They investigated the Hofmann degradation of A-acetylemetine, m.p. 97-9°. This forms a monomethiodide, m.p. 2ia-6°, from which, by the action of silver oxide and potassium hydroxide, followed by eautious tbermal deeomposition and reacetylation,... 

Aristolochic Acid. Rosenmund and Reichstein prepared their material from roots and rhizomes of A. Sipho. It has the formula Cj HjiO N, m.p. 275° (dec.), and forms a methyl ester, m.p. 280° (dec.), [a]n 0°, which is difficult to saponify and on. hydrogenation gives a bright yellow substance, m.p. 312°, which forms a diacetyl... 

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