474 ENOLS AND ENOLATES 18.11 Dehydration of the aldol addition product involves loss of a proton from the a-carbon atom and hydroxide from the B-carbon atom oH O R.C-CHCH R, C=CHCH H,O +HO H H (b) The product of aldol addition of 2-methylbutanal has no a hydrogens. It cannot dehydrate to an aldol condensation product. 2CH3 CH,CHCH CH3CH2CHCH—CCH2CH CH CH HC=O 2-Methylbutanal (c) Aldol condensation is possible with 3-methylbutanal. 2(CH3)2CHCH,CH (CH3)2CHCH, CHCHCH(CH3)h2 (CH3) CHCH,CH=CCH(CH3)2 HC=O 3-Methy butanal Aldol addition product 2-Isopropyl-5-methyl-2-hexenal 18.12 The carbon skeleton of 2-ethyl-1-hexanol is the same as that of the aldol condensation product derived from butanal. Hydrogenation of this compound under conditions in which both the -carbon double bond and the carbonyl group are reduced gives 2-ethyl-l-hexanol CH..CH CHaCH,CH,CH=CCH CHaCH,CH,CH,CHCH,OH CH,CH CHCH 2-Ethyl-2-hexenal 2-Ethyl-1-hexanol 18.13 (b) The only enolate that can be formed from tert-butyl methyl ketone arises by proton abstrac tion from the methyl group. (CH,2 CCCH2 + HO tert-Butyl methyl ate of tert-butyl methyl ketone Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website18.11 Dehydration of the aldol addition product involves loss of a proton from the -carbon atom and hydroxide from the -carbon atom. (b) The product of aldol addition of 2-methylbutanal has no hydrogens. It cannot dehydrate to an aldol condensation product. (c) Aldol condensation is possible with 3-methylbutanal. 18.12 The carbon skeleton of 2-ethyl-1-hexanol is the same as that of the aldol condensation product derived from butanal. Hydrogenation of this compound under conditions in which both the carbon–carbon double bond and the carbonyl group are reduced gives 2-ethyl-1-hexanol. 18.13 (b) The only enolate that can be formed from tert-butyl methyl ketone arises by proton abstrac￾tion from the methyl group. HO O (CH3)3CCCH3 tert-Butyl methyl ketone Enolate of tert-butyl methyl ketone O (CH3)3CCCH2 CH3CH2CH2CH O Butanal 2-Ethyl-1-hexanol CH3CH2CH2CH2CHCH2OH CH2CH3 CH3CH2CH2CH O CCH CH2CH3 2-Ethyl-2-hexenal H2 NaOH, H , Ni 2O heat HO 2(CH3)2CHCH2CH O 3-Methylbutanal (CH3)2CHCH2CHCHCH(CH3)2 HO HC O Aldol addition product (CH3)2CHCH2CH CCH(CH3)2 HC O 2-Isopropyl-5-methyl-2-hexenal H2O 2CH3CH2CHCH CH3 O HO 2-Methylbutanal CH3CH2CHCH CH3 HO CCH2CH3 HC O CH3 (No protons on -carbon atom) H2O HO R2C CHCH O CHCH H O OH R2C OH heat 474 ENOLS AND ENOLATES Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website