215 (8) Ethynylcyclohexane is C≡CH CH3 (h) 3-Ethyl-3-methyl-l-pentyne is CH,CH,CC=CH CHCH 9.20 Ethynylcyclohexane has the molecular formula C&Hi. All the other compounds are CHi 9.21 Only alkynes with the carbon skeletons shown can give 3-ethy lhexane on catalytic hydrogenation 9.22 The carbon skeleton of the unknown acetylenic amino acid must be the same as that of homoleucine The structure of homoleucine is such that there is only one possible location for a carbon-carbon triple bond in an acetylenic precursor. HC≡ CCHCH,CHCO CH CHCHCHCHCO CHNI ChInO Homoleucine 9.23 (a) CH, CH-CH_CH2 CH- CHCI2 2.. NW, CH3 CH,CH_CHIC=CH hexyne 1. NaNH. NH CH CH, CH,CH, CH=CH2 CH CH, CHCH, CHCH, Br CH2CH2CH2CHC≡CH 2-Dibromohexane l-Hexyne HC≡CH HC≡ C Na* CH,CH2 CH- CH,Br CH2CH2CH2CHC≡CH (d) CH_CH__,CH,I DMSO CH3 CH,CH,CH,CHECH I-lodohexane -Hexene 1-Hexene is then converted to l-hexyne as in part(b). 9. 24 (a) Working backward from the final product, it can be seen that preparation of 1-butyne will allow the desired carbon skeleton to be constructed CHaCH,=CCH,CH3 prepared from CH,CH,CEC: BrCH,CH3 3-Hexyne Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website(g) (h) 9.20 Ethynylcyclohexane has the molecular formula C8H12. All the other compounds are C8H14. 9.21 Only alkynes with the carbon skeletons shown can give 3-ethylhexane on catalytic hydrogenation. 9.22 The carbon skeleton of the unknown acetylenic amino acid must be the same as that of homoleucine. The structure of homoleucine is such that there is only one possible location for a carbon–carbon triple bond in an acetylenic precursor. 9.23 (a) (b) (c) (d) 1-Hexene is then converted to 1-hexyne as in part (b). 9.24 (a) Working backward from the final product, it can be seen that preparation of 1-butyne will allow the desired carbon skeleton to be constructed. CH3CH2C CCH2CH3 3-Hexyne CH2CH2C C prepared from BrCH2CH3 CH3CH2CH2CH2CH CH2 1-Hexene CH3CH2CH2CH2CH2CH2I 1-Iodohexane KOC(CH3)3 DMSO HC CH Acetylene CH3CH2CH2CH2C CH 1-Hexyne CNa HC NaNH2 NH3 CH3CH2CH2CH2Br 1-Hexene 1,2-Dibromohexane CH3CH2CH2CH2CH CH2 CH3CH2CH2CH2C CH 1-Hexyne Br2 CCl4 1. NaNH2, NH3 2. H2O CH3CH2CH2CH2CHCH2Br Br 1. NaNH2, NH3 2. H2O CH3CH2CH2CH2CH2CHCl2 1,1-Dichlorohexane CH3CH2CH2CH2C CH 1-Hexyne HC CCHCH2CHCO CH3 NH3 O CH3CH2CHCH2CHCO CH3 NH3 O H2 Pt C7H11NO2 Homoleucine H2 Pt or or 3-Ethyl-1-hexyne 4-Ethyl-1-hexyne 4-Ethyl-2-hexyne 3-Ethylhexane 3-Ethyl-3-methyl-1-pentyne is CH3CH2CC CH2CH3 CH3 CH Ethynylcyclohexane is CH C ALKYNES 215 Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website