Chem 241 Practice Problems for Exam-3 How to do well in the exams: Work the prob

Question

Chem 241 Practice Problems for Exam-3 How to do well in the exams: Work the problems FIRST before you check the answers. Review textbook and notes to make sure you know how to solve the problems instead of just memorizing the answers. Note: 10 Bonus points will be given for students who turned in this practice problems with answers before this exam. Show your works. Part I: Multiple choice questions. 1. Which solvent is suitable for an Sm2 reaction mostly? None of t 2. Which one would be the major product of the following reaction? Br a) 2-Methyl-2-pentene b) 3-Methyl-2-pentene c) 2-Methyl-3-pentene d) 3-Methyl-1-pentene 3. Which of the following compounds will undergo an Su1 reaction most readily? a) (CHs) CCI b) (CHs)>CCH2I c) (CHa)2CHI d) (CHs)2CHCH2CH CH2I 4. Which statement is correct one for the following reaction: (R) 2-Bromobutane NaCN > (R) 2-cyanobutane + (S) 2-cyanobutane a) The leaving group is cyanide. b) It is a Sm2 reaction. c) This is a S1 reaction. d) Elimination is the major reaction. 5. What type of intermediate is present in the sovolysis of 2-bromo-2- methylpropane? a) Radical b) carbocation c) carbanion d) no intermediate

Explanation / Answer

1) option

acetone

For SN2 either less polar or polar aprotic solvents are most suitable.

Aceone is less polar aprotic solvent, thus suits for SN2 reaction.

2)option D

A secondary alkyl halide with a strong, bulky base undergoes E 2 elimination with Hoffman product.

3)option A

For SN1 , the intermediate is a carbocation. Thus the species that can form a stable tertiary carbocation is most likely to follow SN1.

Thus first option a tertiary alkyl halide is the choice.

4) OPTION C

In the given reaction , the products are both enantiomers, that is a racemic mixture is formed.

In an SN1 reaction , the carbocation intermediate is attacked by the nucleophile from either side of the planar carbon, thus leading to a racemic mixture.

So the SN1 reactions are often identified by the formationof both enantiomers (racemic mixture) while the SN2 are identified by the formation of product with inverted configuration only.

5) option b

All solvolysis reactions are SN1 and the intermediate is carbocation.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.