PracticeQuestionsChap8-10

PracticeQuestionsChap8-10 - Chem 2261 Checklist and...

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1 Chem 2261 Checklist and Practice Questions for Chapters 8-10 Chapter 8 Rank alkyl halide substrates in order of reactivity in an S N 2 (or S N 1) reaction. Rank nucleophiles in order of reactivity in an S N 2 (or S N 1) reaction. Rank leaving groups in order of reactivity in an S N 2 (or S N 1) reaction. Rank solvents in terms of effectiveness (reaction rate) in an S N 2 (or S N 1) reaction. Draw and/or explain products (including stereochemical outcome where appropriate) an S N 2 (or S N 1) reaction. Distinguish between substrates and/or reaction conditions likely to favor the S N 2 or S N 1 mechanism for nucleophilic substitution. Carbocation Stability Carbocation Rearrangement. Chapter 9 Draw and/or explain products (including selectivity where appropriate) an E2 (or E1) reaction. Types of Selectivity Regioselectivity Reactions which follow Zaitsev's Rule (i.e., give the more stable alkene product). Exceptions to Zaitsev's Rule (for example: alkyl fluorides). Stereoselectivity Consequences of requirement for C-H and C-X to be antiperiplanar in E2 reactions. Distinguish between substrates and/or reaction conditions likely to favor substitution (S N 2 or S N 1) or elimination (E2 or E1). Chapter 10 Nomenclature of alcohols Conversion of alcohols to alkyl halides By reaction with HX By reaction with PBr 3 , PCl 3 , or SOCl 2 . Conversion of alcohols to alkyl tosylates (ROH to ROTs). Controlling stereochemistry for nucleophilic substitution reactions involving secondary alcohols. Conversion of an alcohol to a halide (using PBr 3 , PCl 3 , or SOCl 2 ) occurs with inversion of configuration (because oxygen of alcohol gets displaced in S N 2 reaction). Conversion of an alcohol to a sulfonate ester occurs with retention of configuration (because carbon- oxygen bond of alcohol retained; no S N 2 displacement) Dehydration (conversion of alcohols to alkenes) 3° alcohols are more reactive (room temp. reaction) and 1° and 2° alcohols (which require heating) 2° and 3° alcohols undergo S N 1 ( look for carbocation rearrangement) 1° undergo S N 2 ( no carbocation rearrangement possible) Formation of Ethers Williamson Ether Synthesis (S N 2 reaction of an alkoxide) Identify preferred alkyl halide/alkoxide combination for synthesis of an unsymmetrical ether. Via carbocation intermediates Formation of epoxides from halohydrins Nucleophilic substitution reactions of epoxides Ring-Opening under Basic Conditions Regiochemistry = Nucleophile adds to less substituted side Ring-Opening under Acidic Conditions Regiochemistry = Nucleophile adds to more substituted side Stereochemistry = inversion of configuration for either type of epoxide ring-opening.
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