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Alkene and Alkyne Mechanisms

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In my organic class we are studying alkenes and alkynes. I am familiar with the addition and elimination procedures. However, I am unclear of how some of the mechanism go since my book only deals with the straight forward mechanisms such as halogenation, hydration, etc. Please see the attachment.

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Solution Summary

The solution is given in an attachment in 350-400 words, explaining the mechanism of alkenes and alkynes.

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Writing Equations for Each of the Given Reagents

1. Write an equation for the reaction of 3-methyl-2-pentene with each of the following reagents:
a. hydrogen bromide
b. BH3 followed by H2O2, OH¯
c. hydrogen (Pt catalyst)
d. KMnO4, OH¯
e. bromine
f. H2O, H+

2. What reagent will react by addition to what unsaturated hydrocarbon to form each of the following compounds?



3. Which of the following reagents is an electrophile? Which is a nucleophile?
a. Br¯
b. BF3
4. Explain in your own words why the water molecule can act either as an electrophile or as a nucleophile.
5. The acid-catalyzed hydration of 1-ethylcyclopentene gives 1-ethylcyclopentanol. Write every step in the mechanism of this reaction. +
6. Draw the resonance contributors to the carbocation CH3CHCH=CHCH2CH3 does the ion have a symmetric structure? (positive sign over the first CH single bond)
7. Adding one equivalent of sulfuric acid to 2,4-hexadiene gives two products. Give the structures, and write all the steps in a reaction mechanism that explains how each product is formed.
8. Predict the product of this Diels-Alder reaction.

9. Write an equation that clearly shows the structure of the alcohol obtained from the sequential hydroboration and H2O2/OH¯ oxidation of 1-methylcyclohexene.
10. Write equations to show how 2-methyl-1-pentene could be converted to
a. 2-hydroxy-2-methylpentane
b. 1-hydroxy-2-methylpentane
11. Write equations for the following reactions:
a. 2-pentyne + H2 (1 mol, Lindlar's catalyst)
b. 1-butyne + HBr (2 mol).

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