Valeric esterification

Promotion of Lipase-Catalyzed Esterification of N-Valeric Acid and Citro-neUol in Supercritical Carbon Dioxide in the Near-Critical Region (Ikushima et al 1996). 

The first synthesis of rfZ-deoxynupharidine was reported by Kotake et al. (30). The starting material w as 2,5-lutidine which was made to react with formaldehyde to give the diol XXVII on dehydration, acetylation, and condensation with malonic ester XXVII afforded the diester XXVIII. On hydrogenation and acid hydrolysis XXVIII was decarboxylated to the valeric acid derivative XXIX. After esterification the acid was acylated with 3-furoyl chloride and distilled with soda lime to yield dehydrodeoxynupharidine (XXX), and this on hydrogenation gave dl-deoxynupharidine (II). 

In the case of ester derivatives the degree of esterification (i.e., mono or diesters) and the size of the esterifying acid helps to determine the extent of lipophilicity of the product. Thus betamethasone 17-valerate (Table 14-1) would be expected to be more soluble in CHC13 (1 2) than the 21 -acetate (1 16), which in turn is more lipid soluble than the alcohol (1 325). Topical antiinflammatory potency parallels such values. 

Butenes are usually derived from Crack-C4 from naphtha steam cracking [27]. After the removal of butadiene (by extraction) and isobutene (by conversion into methyl t-butylether) from the crude stream, the so-called Raffinate II contains 1-butene (50-65%), cis/trons-2-butene, and the isomeric butanes. Raffinate II is the cheapest source of butenes, and their most valuable hydroformylation product is n-pentanal, whereas the isomers 2-methylbutyraldehyde and 3-methylbutyraldehyde are less in demand and lower in value. The main application for -valeraldehyde is its transformation into 2-propylheptanol (2-PH) by aldolcondensation and subsequent hydrogenation of the product (Scheme 14.4) [28, 29]. like 2-EH, 2-PH is also an important plasticizer alcohol. n-Valeraldehyde is also used as an ingredient in flavoring mixtures. w-Valeraldehyde can be converted into -valercarboxylic ester by subsequent oxidation and esterification with tertiary valeric alcohol, providing a useful lubricant and a substitute for Freon. 

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