184 CHAPTER 6The Reactions of Alkynes • An Introduction to Multistep Synthesis Important Termsacetylide ion the conjugate base of a terminal alkyne RCC−aldehyde a compound with a carbonyl group that is bonded to an alkyl group and to a hydrogen (or bonded to two hydrogens). OCRHorOCHHalkylation reaction a reaction that adds an alkyl group to a reactant. alkyne a hydrocarbon that contains a triple bond. carbonyl group a carbon doubly bonded to an oxygen. OCenol an α,β-unsaturated alcohol. OHCgeminal dihalidea compound with two halogen atoms bonded to the same carbon. internal alkynean alkyne with its triple bond not at the end of the carbon chain. keto-enol tautomers a ketone and its isomeric ,-unsaturated alcohol. OCRRCH2ketoenolRCHCROHketone a compound with a carbonyl group that is bonded to two alkyl groups. OCRRπ-complex a complex formed between an electrophile and a triple bond. polymer alarge molecule made by linking up many small molecules called monomers. radical aniona species with a negative charge and an unpaired electron.
Chapter 6 185 retrosynthetic analysis working backward (on paper) from a target molecule to available starting or materials. retrosynthesistautomerizationinterconversion of tautomers. tautomersisomers that are in rapid equilibrium. The keto and enol tautomers differ in the location of a double bond and a hydrogen. terminal alkynean alkyne with its triple bond at the end of the carbon chain. vinylic cationa compound with a positive charge on a vinylic carbon. vinylic radicala compound with an unpaired electron on a vinylic carbon.
186 Chapter 6 Solutions to Problems1.The molecular formula of a noncyclic hydrocarbon with 14 carbons and no πbonds is 14302 +2CH (CH)nn. Because a compound has two fewer hydrogens for every ring and bond, a compound with one ring and 4 bonds (2 triple bonds) would have 10 fewer hydrogens than the 2+2formula. Thus, the molecular formula is 1420. 2. a. 2223ClCH CH CCCH CHc. CH3CHCCH3CHe. HCCCH2CCH3CH3CH3b. d. 2HCCCH Clf. 33CH CCCH3.To answer this question, you need to have the information in Section 6.2. a. 1-bromo-1,3-pentadiene b. 1-hepten-5-yne c. 4-hepten-1-yne 4. HCCCH2CH2CH2CH3CH3CCCH2CH2CH3CH3CH2CCCH2CH31-hexynebutylacetylene2-hexynemethylpropylacetylene3-hexynediethylacetyleneCH3CH2CHCCHCH3CHCH2HCH3CHCCCH33-methyl-1-pentynesec-butylacetylene4-methyl-1-pentyneisobutylacetyleneCH3CH3CH34-methyl-2-pentyneisopropylmethylacetyleneCH3CC3,3-dimethyl-1-butynetert-butylacetyleneCHCH3CH35.a.5-bromo-2-pentyne c.1-methoxy-2-pentyne b.6-bromo-2-chloro-4-octyne d. 3-ethyl-1-hexyne 6. a. 1-hepten-4-yne d. 3-butyn-1-ol b. 4-methyl-1,4-hexadiene e. 1,3,5-heptatriene c.5-vinyl-5-octen-1-yne f. 2,4-dimethyl-4-hexen-1-ol 7. pentane 1-pentene 1-pentyne
Chapter 6 187 8.a.sp2–sp2d.sp–sp3g.sp2–sp3b.sp2–sp3e.sp–sp h. sp–sp3c.sp–sp2f.sp2–sp2i. sp2
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