CHEM 241 TEST 2 OCT. 12, 2016 (WED NAME SCORE PART A (3 ea) Please circle the be

Question

CHEM 241 TEST 2 OCT. 12, 2016 (WED NAME SCORE PART A (3 ea) Please circle the best answer. 1. Which one is the most stable carbocation among the following? e)V a) b) II c) III d)IV 2. What is the element of unsaturation of C,H? d) 5 e) 6 b) 3) c)4 a) 2 3. Which one can be used an electophile? d) nitrate ion c) CH,OH a) nium ion b) chloride ion hydro 4. Which is not true in an electrophilic addition reaction? a) Addition of electophile prefers to form more stable carbocation. b) An electrophile is added first to the double bond. c) Hydroboration oxidation is following the Markovnikovs rule. d Hydroboration oxidation on an alkene gives a carbonyl compound as product. 5. Which reaction of alkene would give the alcohol as its product? d) Acid-Catalyzed c) Bromination b) Epoxidation a) Hydrohalogenation Hydration 6. Which would be most stable among the following four alkene? b) 1-Methylcyclohexene a) Cyclohexene d) 1,3-Dimethylcyclohexene e) 1.2-Dimethylcyclohexene 7, which one would give an epoxide as product when it reacts with cyclohexene? a) HCl with water MCPBA c) oo, with (CH),s d) Br, with CH,0H 8. Which one would be Z isomer? b) 9. What is the right statement for the following compound, 2,4-dichloropentane? III CHo IV CH3 I CH3 CH

Explanation / Answer

1. In the given carbocations, "a) I " is the only tertiary carbocation which can be stabilized by three R groups +inductive effect. Hence, it is the most stable in given carbocations.

2. C5H8 : Element of unsaturation = (2* C + 2 + N - X - H) / 2 = (2* 5 +2 + 0 - 0 - 8) / 2 = 2

Element of unsaturation = 2 Answere is a) 2

3. methenol and chloride ions can not be used as an electrophile (electrophiles are electron defficient centers, and are trying to get electrons). Hence, Nitrate inons can be used as electrophiles.

4. b) an electrophile is added to the double bond first. This is a true statment as double bond act as an nucleophile to attack on electrophile first.

5. Acid catalised hydration adds water molecule across the double bond (C=C) to give alcohol.

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