Biological reaction, alcohol elimination reactions

All three elimination reactions--E2, El, and ElcB—occur in biological pathways, but the ElcB mechanism is particularly common. The substrate is usually an alcohol, and the H atom removed is usually adjacent to a carbonyl group, just as in laboratory reactions. Thus, 3-hydroxy carbonyl compounds are frequently converted to unsaturated carbonyl compounds by elimination reactions. A typical example occurs during the biosynthesis of fats when a 3-hydroxybutyryl thioester is dehydrated to the corresponding unsaturated (crotonyl) thioester. The base in this reaction is a histidine amino acid in the enzyme, and loss of the OH group is assisted by simultaneous protonation. 

Substitution and Elimination Reactions of Alcohols Oxidation Biological Redox Reactions Oxidation of Phenol Synthesis Strategies... 

When complex organic systems have evolved in nature, they are frequently made by the combination of carboxy carbonyl groups and the heteroatoms of alcohols, amines, or thiols. Why The addition-elimination processes introduced in Chapter 19 provide mechanistic pathways of relatively low activation energy for the interconversion of variously substituted carboxylic acid derivatives, many of which play central roles in biology (Chapter 26). Chemists find these compounds similarly useful, as we shall see in this chapter, which deals with the chemistry of four major carboxylic acid derivatives halides, anhydrides, esters, and amides. Each has a substituent, L, that can function as a leaving group in substitution reactions. We already know, for instance, that displace-O... 

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