Which of the following structures is antiaromatic? A) B) C) D) How many electrons are in the HOMO of 1, 3, 5-hexatriene? A) 1 B) 2 C) 4 D) 6 When 1, 3-butadiene is protonated by aqueous sulfuric acid during acid catalyzed hydration, which of the following statements accurately describes the reactive intermediate formed? A) A single carbocation is formed with delocalized partial charges primarily located on 2 different carbons. (B) A single carbocation is formed with a full +1 charge localized exclusively on C2. C) A single carbocation is formed with a full + 1 charge localized exclusively on C1 D) Two different rapidly equilibrating carbocations are formed which give two different products. Which of the following compounds would be the least reactive when reacted with ammonia? A) hexane B) t-butyl bromide C) BF_3 D) concentrated sulfuric acid Which of the following isomeric compounds will react fastest in an Sn2 substitution reaction? A) 2-bromo-2-methylhexane B) 1-bromoheptane C) 2-bromoheptane D) 1-bromo-2, 2-dimethylpentane Which alkene is the most stable? A) cyclohexene B) 1-phenylcyclohexene C) 3-phenycyclohexene D) 1-ethylcyclohexene Which of the following compounds is not aromatic?