prac mid 3 ans

prac mid 3 ans - Chemistry 140A Professor Nathan Gianneschi...

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Unformatted text preview: Chemistry 140A Professor Nathan Gianneschi Winter 2009 Chapter 7-9 Practice Midterm March 18th, 2009 Name:............KEY.......................... First Last Signature:....................................... PID#:.............................................. 1. [6 pts] k1 and k2 are approximately equal for the two reactions shown below despite one being primary and one being secondary. Draw resonance structures to explain this observation. Br Br k1 k2 2. [6 pts] Give the rate equation for an SN1 reaction occurring between H2O and a tertiary alkyl halide, RX. Write your answer in the box below. Rate = k[RX] 3. (a) [6 pts] In the box provided below indicate the product if complete racemization has occurred. H3CH2C H3C C Cl H3CH2C H3 C C OH H2 O Ethanol (H3C)2HC(H2C)3 (H3C)2HC(H2C)3 (b) [4 pts] If ion pairing effects are accounted for, which enantiomer would you expect would be found in higher yield? Write S or R in the box provided. S 4. [38 pts] Propose a synthesis for the compound in box 3 below. Make it in TWO steps from starting materials of 4 carbons or less. HINT: You are going to have to make a new carbon-carbon bond. 1 2 Br THF, Mg MgBr 1) Ether + 2) H+/H2O O 3 OH 5. [40 pts] Fill in all structures in the boxes provided for the reaction scheme indicated. Remember to look at the formulas provided to help you. Appropriate work ups are assumed when not indicated. Br O PBr3 O Ether Mg 1) Diethyl ether MgBr O 2) H+/H2O O OH OH LiAlH4 Diethylether H O O O 15% H2SO4 t-BuOH 40oC, -H2O H HO SOCl2 CH2Cl2 1) H2SO4 50oC 2) NaH, THF Cl O O O ...
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prac mid 3 ans - Chemistry 140A Professor Nathan Gianneschi...

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