Question

- Merdanym i Act antalyzod Hrdian ca Come Lazarmistry I V WORKSHOP #9 Alkenes, Alkynes, Reactions 1. Give a reasonable mechanism for the following reaction. Clearly show intermediates and show the movement of electron pairs with curved arrows. all сна H20. (H2SO4) H₃C CH₂ нас он H3CX сна 2. The addition of HBr to 2-methylpropene can, in principle, give either 1-bromo-2- methylpropane or 2-bromo-2-methylpropane. In reality, only the latter is formed. Show mechanisms for the formation of each of these alkyl bromides, using curved arrows to indicate the flow of electron pairs. Also, construct reaction energy diagrams that describe the energy of the system as a function of the progress in formation of both alkyl bromides. Use these reaction coordinate diagrams to explain why 2-bromo-2-methylpropane is the only product. 3. When one of the stereoisomeric ethylene dicarboxylic acids reacts with C H20, the corresponding chlorohydrin is formed with the stereochemistry as shown below. ноос сі Cl2, H2O HON HOOCHC=CHCOOH ΠΗ H COOH Give the correct stereochemistry for the starting ethylene dicarboxylic acid. Show the detailed mechanism for this reaction suing curved arrows to show the movement of electron pairs. Carefully explain how your mechanism accounts for the stereochemistry of the reactant and the product. 4. Two different compounds having the elemental composition CH 3Br are formed when 1,6-dimethylcyclohexene reacts with hydrogen bromide in the dark and in the absence of peroxides. The same two, compounds are formed from 1,2- dimethylcyclohexene. What are the chemical structures of these two products? OBSERVATION DEDUCTION K= L= J=

How to solve alkene and alkyne reactions

Answer 1

Hydride shift to form more stable carbocation Н Нао Нас Hас-н Hас. Нас H+ H3C H Нас он НаС. Hас. Hас. Hас. H H н Н Н H Br Hас Н-Bг Hас, Нас Вr H Hас Н Hас НаС 2-bromo-2-methylpropane Stable carbocation is favored Нс Hас H-Br Нас Br HаС H,со Нас Н 1-bromo-2-methylpropane less stable carbocation is not favored Not formed CI Н Н CI но CI Н н. но-с "Cooн н' но-с Но-с H H созн но т H HO2с "соон со-н Но-С "соон H Br CH3 CH3 CHз CHз CH3 Br Br-H CH3 CHз HBr Br Н CHз H. Н 1,6-dimethylcyclohex-1-ene CHз CHз Н. CHз Нас. Hас. Hас. Br Brw 1,2-dimethylcyclohex-1-ene