Instructions: 1. Calculators, cell phones and any other electronic devices may N
ID: 593338 • Letter: I
Question
Instructions: 1. Calculators, cell phones and any other electronic devices may NOT be used during the exam. 2. Books or notes are NOT allowed during the exam. 3. Work must be shown where asked in order to receive full credit. 4. Your attention is drawn to the university policy on cheating. This policy will be strictly enforced Q1. When H,O" is added to an alkene A) carbanion B) carbocation C) radical D) acid catalyst is formed as the intermediate. Q2. When HBr is added to an alkene A) carbanion B) radical C) carbene D) None of the above is formed as the intermediate. Q3. When but-1-ene reacts with HBr and H:O2 which of the following structures is formed during the mechanism? A) C) Br D) Q4. The Pi bond in carbon-carbon triple of alkyne is made from overlap of A) sp and sp B) spand sp C) sp and p D) p and p Q. ln (E)·2,7-Dimethyl-3-decen-5-yne the shortest carbon-carbon bond is between carbons-and A) 3 and 4 B) 5 and 6 C) 7 and 8 D) 1 and 2Explanation / Answer
1) option B
When H3O+ is added to alkene, the H= is added to double bond giving a carbocation
R-CH=CH2 + H+ ------------> RCH+-CH3
2) OPtion D
When HBr is treated with alkene, H of HBr is added to double giving a carbocation intermediate.
3) option D
addition of HBr in the presence of peroxide follows free radical mechanism with the initial addition of Br radical to the double bond givng the free radical .
4) oprion D
A pi bond is always formed between pure unhybridised orbitals.
5)OPtion B
The triple bond is the shortest bond between C-C. and in the given molecule of (5-yne) the triple bond is between 5 and 6 carbons.