Organic Chemistry, 6 th edition Paula Yurkanis Bruice Chapter 12 Radicals: Reactions of Alkanes Brian L. Groh Minnesota State University, Mankato Mankato, MN Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

What is the first step in radical halogenation of alkanes? 12.2 A.Abstraction B.Initiation C.Propagation D.Combination E.Termination Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

What is the first step in radical halogenation of alkanes? 12.2 A.Abstraction B.Initiation C.Propagation D.Combination E.Termination Initiation is the “initial” step in a radical process. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

A.5% B.15% C.29% D.41% E.71% Calculate the percentage yield of the product below formed by radical bromination. [Relative reactivities: 1°(1), 2°(82), 3°(1600)] 12.4 Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

A.5% B.15% C.29% D.41% E.71% Calculate the percentage yield of the product below formed by radical bromination. [Relative reactivities: 1°(1), 2°(82), 3°(1600)] 12.4 % yield = relative reactivity X no. H’s *100 sum of relative amounts Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

Which compound will predominate in the radical bromination of 1-methylcyclohexene? 12.6 Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

Which compound will predominate in the radical bromination of 1-methylcyclohexene? 12.6 In radical additions, the bromine radical adds to the least substituted carbon of the C=C. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

Rank the radicals in decreasing order of stability A.1 > 2 > 3 > 4 B.4 > 3 > 2 > 1 C.3 > 4 > 2 > 1 D.1 > 2 > 4 > 3 E.4 > 2 > 3 > 1 Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

Rank the radicals in decreasing order of stability A.1 > 2 > 3 > 4 B.4 > 3 > 2 > 1 C.3 > 4 > 2 > 1 D.1 > 2 > 4 > 3 E.4 > 2 > 3 > 1 The allyl radical is resonance stabilized. The other radicals are only weakly stabilized by hyperconjugation. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

Which compound will give one product upon radical bromination using NBS, ROOR, and heat? 12.8 Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

Which compound will give one product upon radical bromination using NBS, ROOR, and heat? 12.8 In compound A, abstraction of any allylic hydrogen leads to only one resonance stabilized allylic radical. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

Which reaction sequence would likely give the product in reasonable yield? Bruice: Organic Chemistry, © 20101Pearson Education, Inc. A. 1. Br 2 /h ʋ ; 2. (CH 3 ) 3 COK/(CH 3 ) 3 COH; 3. CH 3 CO 3 H; 4. CH 3 O - /CH 3 OH B. 1. Br 2 /ROOR, h ʋ ; 2. HO - /H 2 O 3. CH 3 CO 3 H; 4. H + /CH 3 OH C. 1. Br 2 /h ʋ ; 2. (CH 3 ) 3 COK/(CH 3 ) 3 COH; 3. H 2 O 2 /H 2 O; 4. CH 3 O - /H 2 O D. 1. NBS/h ʋ ; 2. CH 3 O - /CH 3 OH; 3. H 2 O 2 /THF; 4. H 2 O/CH 3 OH E. 1. NBS/h ʋ ; 2. CH 3 O - /CH 3 OH; 3. CH 3 CO 3 H; 4. H + /CH 3 OH

Which reaction sequence would likely give the product in reasonable yield? Bruice: Organic Chemistry, © 2011 Pearson Education, Inc. A. 1. Br 2 /h ʋ ; 2. (CH 3 ) 3 COK/(CH 3 ) 3 COH; 3. CH 3 CO 3 H; 4. CH 3 O - /CH 3 OH B. 1. Br 2 /ROOR, h ʋ ; 2. HO - /H 2 O 3. CH 3 CO 3 H; 4. H + /CH 3 OH C. 1. Br 2 /h ʋ ; 2. (CH 3 ) 3 COK/(CH 3 ) 3 COH; 3. H 2 O 2 /H 2 O; 4. CH 3 O - /H 2 O D. 1. NBS/h ʋ ; 2. CH 3 O - /CH 3 OH; 3. H 2 O 2 /THF; 4. H 2 O/CH 3 OH E. 1. NBS/h ʋ ; 2. CH 3 O - /CH 3 OH; 3. CH 3 CO 3 H; 4. H + /CH 3 OH Acceptable reactions: Step 1 – A, B, or C; Step 2 – A and C are best; Step 3 – A, B or E; Step 4 – only A