1.15: Elimination Reactions and Alkene Synthesis Exercises
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1) One of the products that results when 1-bromo-2,2-dimethylcyclopentane is heated in ethanol is shown below. Give a mechanism by which it is formed and give the name of this mechanism.
2) Provide the structure of the major organic product in the following reaction
3) Provide the structure of the major organic product from following reaction
4) Which diastereomer of 1-bromo-4-t-butylcyclohexane, the cis or the trans, undergoes elimination more rapidly when treated with sodium ethoxide? Explain your answer.
5) Provide the structure of the major organic product from the following reaction.
6) When 1-iodo-1-methylcyclohexane is treated with NaOCH2CH3 as the base, the more highly substituted alkene product predominates. When KOC(CH3)3 is used as the base, the less highly substituted alkene predominates. Give the structures of the two products and offer an explanation.
7) Which of the following statements apply to E1 reactions of alkyl halides? Choose as many as necessary.
I. Rate = k[base]
II. Rate = k[base][RX]
III. Rate = k[RX]
IV. The reactions occur in two or more distinct steps.
V. Rearrangements are sometimes seen.
8) What is Saytzeff's rule?
9) What major product results when 2-bromo-2-methylbutane is treated with sodium ethoxide.
10) How many distinct alkenes can result from E2 elimination of the compound below? Give their structures and IUPAC names.
11) Give the major product and the mechanism of the following reaction
12) Predict the most likely mechanism and the product for the reaction below.
13) Predict the most likely mechanism and the product from the reaction between 2-chloro-2-methylpentane and sodium ethoxide in ethanol.
14) The major product which results when 2-chloro-2-methylpentane is heated in ethanol is an ether. Show and name the mechanism by which this ether forms.
15) Which of the following mechanisms feature carbocation intermediates?
A) SN1 only
B) SN2 only
C) E1 only
D) E2 only
E) both SN1 and E1
16) Which mechanism(s) give(s) alkenes as the major products, Sn1, Sn2, E1, or E2?
17) Which compound produces only one alkene when treated with sodium methoxide?
18) When 3-iodo-3-ethylpentane is treated with sodium methoxide in methanol, the major organic product is an ______ that is generated through an ______ mechanism.
A) ether, SN1 B) ether, SN2 C) ether, E1 D) alkene, E2 E) alkene, E1
19) Provide the structure of the major alkene product of the reaction below
20) Based on Saytzeff's rule, select the most stable alkene.
D) They are all of equal stability
21) Based on Saytzeff's rule, select the most stable alkene.
D) They are all of equal stability
FOR QS. 22-24, DRAW ALL ALKENE PRODUCTS AND CIRCLE THE PREDOMINANT ONE
25) Propose a detailed, step-by-step mechanism for the reaction shown below.
26) Draw all likely products of the following reaction and circle the product you expect to predominate.
27) Draw all likely products of the following reaction and circle the product you expect to predominate.
28) Which base, ammonia (NH3) or triethylamine [(CH3CH2)3N], would be more effective to use for the following conversion?
29) Which compound would undergo dehydrohalogenation with strong base to give the alkene shown below as the only alkene product?
FOR SYNTHESES # 30-32 GIVE THE MISSING REAGENTS AND STRUCTURES.
33) Which of the following statements applies to the E2 mechanism?
A) It occurs with inversion of stereochemistry.
B) It occurs with racemization of stereochemistry.
C) It proceeds through the more stable carbocation intermediate.
D) The C-H and C-X bonds that break must be anti.
E) Use of a bulky base gives the more highly substituted alkene product.