8Aworksheet5 - Chem 8A Worksheet 5 Concepts nucleophiles...

Unformatted text preview: Chem 8A Worksheet 5 Concepts: nucleophiles electrophiles reaction coordinate diagrams reaction mechanisms alkene reactions carbocation stability reaction of alkynes Practice Problems: 1) Indicate whether each of the following molecules is more liker to behave as an electrophile or a nucleophile, and then explain your choice. (Put an “E” in the box if you think the molecule will behave like an electrophile and put an “N” in the box if you think the molecule will behave like a nucleophile.) \ CH3CH2 E] H306) D 9°” NaCN CH3Li [l D E D 2) Which of the following molecules is the best nucleophile? Circle your answer and provide a brief fl}. #0/ Ni. explanation. 3) Consider the following reaction steps. Label which compound is the nucleophile and which is the electrophile in the reaction step, draw any relevant lone pair electrons, and then draw curved arrows showing the electron movement between the reagents. CH3 a) H\ [H + CH3 )\/CH3 0 H c)\/CH3 Hac 3 (+3 H’%H 69 b Br ) [A + eo‘CHa ——_' Br/VO\CH3 0) o e (34” + CEN —-—-—> @oN ’ a. What are the possible products? The major product? b. What is the name of the carbon intermediate that forms in this reaction? c. Draw the reaction mechanism using curved arrows. 5) Consider the reaction coordinate diagram below to answer the following questions: l Free energy (G) ————-—> progress of reaction How many intermediates are present in the following reaction diagram? How many transition states are present in the following reaction diagram? Which is more stable, reactants or products? ‘ 6) Draw and label the reaction coordinate diagram for the reaction presented in question 4. 7) Which of the carbocations in the following pair is more stable? Briefly explain your answer. /\CH2 vs WCHa C9 C9 (9 69 H3C\ ,CH2 vs HscxN/CH2 0 H 8) Determine the total number of pi bonds and/or rings for the following hydrocarbons: CIOHM D CAOHSB {:l 9) Draw the structure for each of the following: a. 2-hexyne b. 4-bromo-1-octyne c. 4,4—dimethyl-1-pentyne 10) Give the major product(s) for the following reactions: CH3CHZCH2CECH L excess HBr —————D- % 0/ H2 i Pt/C H2 _ ——-—+. ——/——=’/ Lindlar catalyst HSO < :>—CH2CECCHCH3 + H20 _i_4_.> ...
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