Chapter 18-3

Chapter 18-3 - CHEM 262 Wei You Chapter 18. Functional...

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Unformatted text preview: CHEM 262 Wei You Chapter 18. Functional Derivatives of Carboxylic Acids (3) Rxn with Alcohols Acid halides react with alcohols to give esters acid halides are so reactive toward even weak nucleophiles such as alcohols that no catalyst is necessary when the alcohol or resulting ester is sensitive to HCl, reaction is carried out in the presence of a 3 amine to neutralize the acid Butanoyl chloride Cyclohexyl butanoate + Cyclohexanol HO HCl Cl O + O O Rxn with Alcohols sulfonic acid esters are prepared by the reaction of an alkane- or arenesulfonyl chloride with an alcohol or phenol the key point here is that OH- (a poor leaving group) is transformed into a sulfonic ester (a good leaving group) with retention of configuration at the chiral center OH TsCl OTs ( R )-2-Octanol p- Toluenesulfonyl chloride (Tosyl chloride) ( R )-2-Octyl p-t oluenesulfonate [( R )-2-Octyl tosylate] + pyridine Rxn with Alcohols Acid anhydrides react with alcohols to give one mole of ester and one mole of carboxylic acid cyclic anhydrides react with alcohols to give one ester group and one carboxyl group CH 3 COCCH 3 O HOCH 2 CH 3 CH 3 COCH 2 CH 3 O CH 3 COH O Acetic acid Ethyl acetate Ethanol Acetic anhydride + + (sec-Butyl hydrogen phthalate 2-Butanol ( sec- Butyl alcohol) + Phthalic anhydride O O O O OH HO O O Rxn with Alcohols aspirin is synthesized by treating salicylic acid with acetic anhydride Acetylsalicylic acid (Aspirin) 2-Hydroxybenzoic acid (Salicylic acid) + + Acetic acid A cetic anhydride CH 3 COH CH 3 COCCH 3 O O COOH CH 3 O OH COOH O O Rxn with Alcohols Esters react with alcohols in the presence of an acid catalyst in an equilibrium reaction called transesterification Butyl propenoate (Butyl acrylate) (bp 147C) 1-Butanol...
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This note was uploaded on 03/22/2009 for the course CHEM 262 taught by Professor Forbes during the Spring '08 term at UNC.

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Chapter 18-3 - CHEM 262 Wei You Chapter 18. Functional...

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