HW20Key - amount? Indicate your answer by marking the box...

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Graded Homework Problem #20 – Answer Key This problem is worth a total of 20 raw points. When ( S )-3-bromo-2,3-dimethylpentane (shown below) is dissolved in H 2 O/acetone, the resulting solution is optically active . When this solution is heated to 60°C, the alkyl bromide disappears, and a mixture of products is formed. This product mixture is optically inactive . One of the products isolated (as a racemic mixture) is an alcohol having the molecular formula C 7 H 16 O. (HW#18 asked you to deduce the structure of this product and to propose a mechanism for its formation.) Four different hydrocarbons, all having molecular formula C 7 H 14 , can also be isolated from the same product mixture. Propose structures for all 4 of these hydrocarbons. Write your answers in the boxes below. Which of these hydrocarbons would be expected to form in the greatest
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Unformatted text preview: amount? Indicate your answer by marking the box labeled MAJOR PRODUCT with the symbol X. Propose a mechanism to account for formation of this major hydrocarbon product . CH 3 CH 3 H Br C 7 H 16 O ( S )-3-Bromo-2,3-dimethylpentane H 2 O/acetone (racemic) + (4 d i f f e r e n t isomers; draw 1 per box below) C 7 H 14 MAJOR PRODUCT MAJOR PRODUCT MAJOR PRODUCT MAJOR PRODUCT ( E ) ( Z ) X The four different hydrocarbons correspond to the four different alkenes that can form if the starting material undergoes an E1 reaction. In general, when more than one alkene product is possible in an E1 reaction, the major product is the most highly substituted (most stable) alkene. The mechanism that explains formation of this product is given below: H 3 C H 3 C H Br H 3 C H CH 3 H O H CH 3 CH 3 H O H H Br...
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