Acids catalytic hydrogenation

Protons present in aqueous acid also act as reasonably efficient electron acceptors. If the reduced hydrogen atoms are formed on metallized suspensions, catalytic hydrogenation can result. For example, in contrast to the oxidative chemistry reported earlier for cyclohexene-4,5-bis-dicarboxylic acid (Eq. 28), if the reaction is conducted in the absence of oxygen in aqueous nitric acid, catalytic hydrogenation of the double bond becomes a major pathway, Eq. (34). ... 

Index Entries Glutamic acid catalytic hydrogenation pyroglutaminol pyroglutamic acid phosphoric acid prolinol. 

Fatty acids (the carboxylic acids produced by saponification of fats) usually have an even number of carbons and may also have one or more cis double bonds. The fatty acid that has 18 carbons with a cis double bond at the 9 position, (Z)-9-octadecenoic acid, is called oleic acid. Catalytic hydrogenation of oleic acid produces stearic acid, or octadecanoic acid, another fatty acid. One of these fatty acids melts at 13.4°C and the other melts at 69.6°C. Explain which fatty acid melts at the higher temperature. 

As contrasted with the vigorous catalytic hydrogenation, the reduction with LiAlH4 is unlikely to lead to the complete elimination of the oxido oxygen. Sec.-tert. epoxides form tert. carbinols in most cases, while a sec. hydroxyl group is formed by acid catalytic hydrogenation.—E a-ChoIesterol oxide acetate 3yJ,5-dihydroxycholestane. Y. 95%. (F. e. s. P. A. Plattner, H. Heusser et al., Helv. 32, 587,1070 (1949).) s. a. 4, 50 L. W. Trevoy and W. G. Brown, Am. Soc. 71, 1675 (1949)... 

Buchanan et al. have recently proposed XXVIII as the structure of oxycolchicine on the basis of chemical and NMR-evidence (33). Boro-hydride reduction of XXVIII gave XXIX, which showed only an amide band in the carbonyl region of the IR-spectrum. XXIX could be transformed into colchiceine by treatment with acid. Catalytic hydrogenation of oxycolchicine provided a hexahydro compound (XXX) which formed a monoacetate, indicating that the ether linkage was still intact. Compound XXVIII was reduced by lithium aluminum hydride to an amine... 

Carboxylic Acids. - Catalytic hydrogenation of carboxylic acids is very difficult to perform, although the use of Ru, RUO2, or Cu-Cr203 or Re catalysts at high temperatures and pressure results in the hydrogenation to alcohols. ... 

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