Problem Set 5 in Chem 220a: Alkyl Halides and Ethers Reactions, Assignments of Organic Chemistry

Download Problem Set 5 in Chem 220a: Alkyl Halides and Ethers Reactions and more Assignments Organic Chemistry in PDF only on Docsity! PS5.html Page 1 Wed, Oct 10, 2001 1:19 PM Chem 220a Problem Set 5 Chapter 6 Due: Monday, October 15, 2001 1. Study #2 and #3 in the Alkyl Halide module and #1 in the Ether module in ORGO. 2. Consider each of the compounds 1 and 2 as a racemate. a) What is their relationship to one another? b) Which one undergoes elimination faster? Explain and illustrate. What is the structure of the product? Is it optically active? c) Consider structures 1 and 2 as the enantiomers shown. They differ only in the configuration at the carbon bearing bromine, and neither one is superimposable on its own mirror image. Thus, both stereoisomers are capable of existing as enantiomers. The only "chiral carbons" in 1 (and 2 also but you need not do this one) are the ones bearing deuterium. R. S. Cahn (left), C. Ingold, and V. Prelo (1966) [One wag has suggested that "R" and "S" were chosen by Cahn for the CIP system for an obvious reason.] What is the common configuration (R,S) at these carbons? The carbons bearing the Br- and t-butyl groups are not chiral (why?) but they are stereogenic. Explain. [Hint: Try to use R and S on the carbons bearing the Br- and t-butyl groups. Any luck? Try inverting the configuration at the carbons bearing the Br- and t-butyl groups. What happens?] PS5.html Page 2 Wed, Oct 10, 2001 1:19 PM 3. Predict and explain the formation of each of the products of the following reactions. Be sure to address issues of stereochemistry and optical activity. 4. An optically active compound (R)-A, C 5 H 11 Cl, undergoes free radical chlorination to give 5 constitutional (structural) isomers (C 5 H 10 Cl 2 ), one of which is a pair of diastereomers. Dichlorides B and C are optically inactive while the remaining four, D, E, F, and H are optically active. The pair of diastereomers is D and E. The carbon bearing the new chlorine atom in E is of the (S)-configuration. Compound C reacts more rapidly with water than any of the dichlorides and forms compound G, C 5 H 11 ClO. Dichloride H is geminally substituted. What are the structures of A-H? Provide R/S configurations for D, E, F, and H. Include explanations for the following: a) Why are B and C optically inactive?, b) Why does C react rapidly with water?, c) Is G optically active? Explain.