Pettit

Catalytic hydrogenation is mostly used to convert C—C triple bonds into C C double bonds and alkenes into alkanes or to replace allylic or benzylic hetero atoms by hydrogen (H. Kropf, 1980). Simple theory postulates cis- or syn-addition of hydrogen to the C—C triple or double bond with heterogeneous (R. L. Augustine, 1965, 1968, 1976 P. N. Rylander, 1979) and homogeneous (A. J. Birch, 1976) catalysts. Sulfur functions can be removed with reducing metals, e. g. with Raney nickel (G. R. Pettit, 1962 A). Heteroaromatic systems may be reduced with the aid of ruthenium on carbon. 

Usually esters cannot be reduced directly to the corresponding ethers. Eflicient conversion with the NaBH4 —BF3 reagent is only possible, if the alcohol component is tertiary (G.R. Pettit, 1962 B). 

Single-bond cleavage with molecular hydrogen is termed hydrogenolysis. Palladium is the best catalyst for this purpose, platinum is not useful. Desulfurizations are most efficiently per-formed with Raney nickel (with or without hydrogen G.R. Pettit, 1962 A or with alkali metals in liquid ammonia or amines. The scheme below summarizes some classes of compounds most susceptible to hydrogenolysis. 

C. L. Brooks III, M. Karplus, and B. M. Pettit, Proteins A Theoretical Perspective of Dynamics, Structure andThermodynamics,]oha WUey Sons, New York, 1988. 

G. S. Giggias and E. S. Pettit, Pratt and Whitney Mircraft, report no. ER-11545, East Hartford, Conn., Sept. 1978. 

M. Bodansky, Peptide Synthesis, 2nd ed., John Wiley Sons, Inc., New York, 1976 J. Meinhofer in Ref. 1, Chapt. 9, p. 297 G. R. Pettit, Synthetic Peptides, Vols. 1—4, Van Nostrand Reinhold, New York, 1980, Vols. 5, 6, Elsevier New York, 1982 E. Shroeder and K. Luebke, The Peptide, Vol. 1, Methods of Peptide Synthesis, Academic Press, New York, 1965 N. Izumiya and co-workers. Fundamentals and Experiments of Peptide Synthesis (in Japanese), Mamzen, Tokyo, Japan, 1987 R. B. Merriheld,/ Mm. Chem. Soc. 85, 2149 (1963) G. Barany and R. B. Merriheld in E. Gross andj. Meinenhofer, eds.. The Peptides Mnalysis, Synthesis, Biology, Vol. 2, Academic Press, New York, 1980, pp. 1—284 G. R. Marshall, Peptides Chemistry and Biology, Escom, Leiden, The Netherlands, 1988. 

It has been recrystd from H2O (fine needles) and is freely soluble in boiling H2O. Crysts also from H2O by addition of acetone. Purified by chromatography on Dowex 1 (in formate form), eluting with 0.25M formic acid. It was then adsorbed onto charcoal (which had been boiled for 15min with M HCI, washed free of chloride and dried at 100°), and recovered by stirring three times with isoamyl alcohol/H20 (1 9 v/v). The aqueous layer from the combined extracts was evaporated to dryness under reduced pressure, and the product was crystallised twice from hot H2O. [Morrison and Doherty Biochem J19 433 7967]. It has A-max 259nm (e 15,400) in H2O at pH 7.0. [Alberty et al. J Biol Chem 193 425 7957 Martell and Schwarzenbach Heh Chim Acta 39 653 7956]. The acridinium salt has m 208° [Baddiley and Todd J Chem Soc 648 1947 Pettit Synthetic Nucleotides, van Nostrand-Reinhold, NY, Vol 1 252 1972 NMR Sarma et al. J Am Chem Soc 96 7337 1974 Norton et al. J Am Chem Soc 98 1007 1976 IR of diNa salt Miles Biochem Biophys Acta 27 324 1958],... 

L. G. SiLLfiN and A. E. Martell, Stability Constants of Metal-ion Complexes, The Chemical Society, London, Special Publications No. 17, 1964, 754 pp., and No. 25, 1971, 865 pp. Stability Constants of Metal-lon Complexes, Part A. Inorganic Ligands (E. Hcigfeldt, ed.), 1982, pp. 310, Part B. Organic Ligands (D. Perrin, ed.), 1979, pp. 1263. Pergamon Press, Oxford. A continually updated database is now provided by L. D. Pettit and K. J. Powell (eds.), IVPAC Stability Constants Database, lUPAC and Academic Software. 

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