ALDEHYDES AND KETONES: NUCLEOPHILIC ADDITION TO THE CARBONYL GROUP 427 17.2 (b) First write the structure from the name given. Ethyl isopropyl ketone has an ethyl group and an isopropyl group bonded to a carbonyl group CH.CCHCH H3 Ethyl isopropyl ketone may be alternatively named 2-methyl-3-pentanone Its longest contin uous chain has five carbons. The carbonyl carbon is C-3 irrespective of the direction in which the chain is numbered, and so we choose the direction that gives the lower number to the sition that bears the methyl group (c) Methyl 2, 2-dimethylpropyl ketone has a methyl group and a 2, 2-dimethylpropyl g bonded to a carbonyl group o CH CH. CCHCCH The longest continuous chain has five carbons, and the carbonyl carbon is C-2. Thus, methyl 2, 2-dimethylpropyl ketone may also be named 4, 4-dimethyl-2-pentanone (d) The structure corresponding to allyl methyl ketone is O CH,CH=CH, Because the carbonyl group is given the lowest possible number in the chain, the substitutive name is 4-penten-2-one not 1-penten-4-o1 17.3 No Lithium aluminum hydride is the only reagent we have discussed that is capable of reducing carboxylic acids(Section 15.3) 17. 4 The target molecule, 2-butanone, contains four carbon atoms. The problem states that all of the car bons originate in acetic acid, which has two carbon atoms. This suggests the following disconnections H CHa CCH,CH3 CH; CHCH,CH CHCH CHCH The necessary aldehyde(acetaldehyde) is prepared from acetic acid by reduction followed by on CH- COH 1.LiAIH. CH, CH2OH 2.H,O CH3CH Acetic acid Ethanol Ethylmagnesium bromide may be obtained from acetic acid by the following sequence CHCHOH HBr or CH CHBI CHCHMgBr Ethanol Ethyl bromide Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE WebsiteALDEHYDES AND KETONES: NUCLEOPHILIC ADDITION TO THE CARBONYL GROUP 427 17.2 (b) First write the structure from the name given. Ethyl isopropyl ketone has an ethyl group and an isopropyl group bonded to a carbonyl group. Ethyl isopropyl ketone may be alternatively named 2-methyl-3-pentanone. Its longest contin￾uous chain has five carbons. The carbonyl carbon is C-3 irrespective of the direction in which the chain is numbered, and so we choose the direction that gives the lower number to the po￾sition that bears the methyl group. (c) Methyl 2,2-dimethylpropyl ketone has a methyl group and a 2,2-dimethylpropyl group bonded to a carbonyl group. The longest continuous chain has five carbons, and the carbonyl carbon is C-2. Thus, methyl 2,2-dimethylpropyl ketone may also be named 4,4-dimethyl-2-pentanone. (d) The structure corresponding to allyl methyl ketone is Because the carbonyl group is given the lowest possible number in the chain, the substitutive name is 4-penten-2-one not 1-penten-4-one. 17.3 No. Lithium aluminum hydride is the only reagent we have discussed that is capable of reducing carboxylic acids (Section 15.3). 17.4 The target molecule, 2-butanone, contains four carbon atoms. The problem states that all of the car￾bons originate in acetic acid, which has two carbon atoms. This suggests the following disconnections: The necessary aldehyde (acetaldehyde) is prepared from acetic acid by reduction followed by oxidation in an anhydrous medium. Ethylmagnesium bromide may be obtained from acetic acid by the following sequence: CH3CH2OH Ethanol (Prepared as previously) CH3CH2Br Ethyl bromide CH3CH2MgBr Ethylmagnesium bromide HBr or PBr3 Mg diethyl ether CH3CO2H Acetic acid CH3CH2OH Ethanol CH3CH O Acetaldehyde 1. LiAlH4 2. H2O PDC CH2Cl2 CH3CHCH2CH3 OH CH3CCH2CH3 O O CH3CH CH2CH3 2-Butanone CH3CCH2CH CH2 O CH3CCH2CCH3 CH3 O CH3 CH3CH2CCHCH3 O CH3 Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website