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CHAPTER 15AN INTRODUCTION TO ORGANOMETALLIC COMPOUNDSMULTIPLE CHOICE

1.What term describes the process whereby an alkyl halide undergoes reaction with magnesium metal to give an alkylmagnesium bromide (Grignard reagent)?

a.nucleophilic substitution

b.electrophilic addition

c.oxidative addition

d.reductive elimination

ANS:C

2.What is the change in oxidation state of the metal when magnesium reacts with an alkyl bromide to give an alkylmagnesium bromide (Grignard reagent)?

a.0 +1

b.0 +2

c.0 1

d.0 2

ANS:B

3.Which of the following is the best choice of solvent for the formation of phenylmagnesium bromide by the reaction of bromobenzene with magnesium?

a.water

b.methanol

c.diethyl ether

d.

ANS:C

4.Which of the following is the best choice of solvent for the formation of phenyllithium by the reaction of bromobenzene with lithium?

a.water

b.ethanol

c.tetrahydrofuran

d.acetic acid

ANS:C

5.Which of the following bonds has the most ionic character?

a.CAl

b.CHg

c.CMg

d.CZn

ANS:C

6.Which of the following bonds has the most ionic character?

a.CSn

b.CCu

c.CZn

d.CLi

ANS:D

7.Which of the following compounds is the strongest base?

a.CH3CH2MgBr

b.CH3CH2OH

c.CH3CH2OMgBr

d.CH3CH3

ANS:A

8.Which of the following compounds is the strongest base?

a.NaOH

b.NH3

c.CH3Li

d.CH3OH

ANS:C

9.Which of the following molecules are deprotonated by ethylmagnesium bromide?

a.phenol, PhOH

b.propyne, CH3CCH

c.dimethylamine, (CH3)2NH

d.all of these

ANS:D

10.Which of the following mechanisms accounts for the acid-base reaction of ethylmagnesum bromide with acetylene to give acetylide anion?

a.1

b.2

c.3

d.4

ANS:A

11.What is the major organic product obtained from the following sequence of reactions?

a.2-methylbutane

b.3-methyl-1-butanol

c.3-methyl-2-butene

d.3-methyl-2-butanol

ANS:A


a.2-pentanol

b.pentane

c.1-pentene

d.(E)-2-pentene

ANS:B

13.What is the major organic product obtained from the following reaction?

a.1

b.2

c.3

d.4

ANS:B


a.1

b.2

c.3

d.4

ANS:D

15.Which of the following alcohols can be prepared from a Grignard reagent and ethylene oxide?

a.only 1

b.only 1 and 2

c.only 1, 2 and 3

d.1, 2, 3 and 4

ANS:B

16.Which of the following alcohols can be prepared from a Grignard reagent and ethylene oxide?

a.only 1 and 2

b.only 1 and 4

c.only 1, 2 and 3

d.only 2 and 4

ANS:D


a.1

b.2

c.3

d.4

ANS:B


a.1

b.2

c.3

d.4

ANS:C

19.Which combination(s) of alkyl bromide and epoxide can be used to prepare the following product by addition of the Grignard reagent derived from the alkyl bromide to the epoxide?

a.only 1

b.only 2

c.only 1 and 3

d.only 2 and 4

ANS:B

20.Which combination(s) of alkyl bromide and epoxide can be used to prepare the following product by addition of the Grignard reagent derived from the alkyl bromide to the epoxide?

a.only 1

b.only 2

c.only 1 and 3

d.only 2 and 4

ANS:A


a.1

b.2

c.3

d.4

ANS:A


a.(E) 2-iodo-2-butene

b.1-iodo-2-methylpropene

c.methylcyclopropane

d.(E) 2-butene

ANS:D


a.1

b.2

c.3

d.4

ANS:A


a.2-methylheptane

b.3-methylheptane

c.2-methyloctane

d.3-methyloctane

ANS:C


a.(E) 6,6-dimethyl-1-hexene

b.(E) 5,5-dimethyl-1-heptene

c.(E) 6,6-dimethyl-1-heptene

d.(E) 6,6-dimethyl-2-heptene

ANS:D


a.(Z)-6-methyl-2-heptene

b.(E)-4-methyl-2-pentene

c.2-methylheptane

d.3-methylheptane

ANS:C


a.2-iodo-7-methyloctane

b.(E)-7-methyl-1-octene

c.(E)-7-methyl-2-octene

d.(E)-7-methyl-3-octene

ANS:D

28.Which of the following is not true regarding the carbon atom of the methylene carbene, H2C: ?

a.it is sp2 hybridized

b.it has a complete octet of valence electrons

c.it has a vacant 2p atomic orbital

d.it has a lone pair of electrons in an sp2 molecular orbital

ANS:B

29.What reactive intermediates are involved in the following reaction?

a.the trichloromethyl anion (Cl3C:) and dichlorocarbene (Cl2C:)

b.the trichloromethyl cation (Cl3C+)

c.the cyclohexyl carbocation

d.the cyclic chloronium ion derived from cyclohexene

ANS:A


a.

b.2

c.3

d.4

ANS:C


a.1

b.2

c.3

d.4

ANS:B


a.1

b.2

c.3

d.4

ANS:C


a.1

b.2

c.3

d.4

ANS:A


a.1

b.2

c.3

d.4

ANS:B


a.1

b.2

c.3

d.4

ANS:C

TRUE/FALSE

1.The reaction of an alkene with dichlorocarbene is stereospecific.ANS:T

2.The following reaction would be classified as a Simmons-Smith reaction.

ANS:T

3.The product of the following reaction would be a cyclopropane.

ANS:T

4.The following conversion could be accomplished using a Grignard reaction.

ANS:F

5.In a coupling reaction using a Gilman reagent, both of the Gilman reagent alkyl groups are transferred in the reactionANS:F

6.Both Grignard reagents and Gilman reagents are synthetically useful because they form new carbon to carbon bonds.ANS:T

7.In the formation of the ether soluble complex in a Grignard reaction, magnesium acts as a Lewis base and the ether as a Lewis acid.ANS:F

8.The percent ionic character of a CMg bond is less than that of a CCu bond.ANS:F

9.In organometallic bonds, carbon attains a partial negative charge which makes it both basic and nucleophilic.ANS:T

COMPLETIONConsider the following reaction to answer the following question(s).

1.Substance A is termed a ___________reagent.ANS:

Grignard

2.Substance ____ is the nucleophile in the reaction.ANS:A

3.Substance ____ is the electrophile in the reaction.ANS:B

4.Substance A is formed from the reaction of Mg with ______________.ANS:bromocyclohexaneConsider the reaction below to answer the following question(s).

5.The reaction intermediate formed by the reaction of KOH with the alkene is called_____________.ANS:dichlorocarbene

6.In this reaction the alkene would be classified as the:

a. electrophile

b. nucleophile

c. Lewis base

d. both b and cANS:a

7.Name the product of the following reaction.

ANS:

cis-1,2-dimethylcyclopropaneConsider the following conversion.

Use this reacton to answer the following questions.

8.The first step in this conversion would be reaction with:

a. Mg/ether

b. PCC

c. oxiraneANS:a

9.The second step in this conversion would be reaction with:

a. Mg/ether

b. PCC

c. oxiraneANS:c

10.The first step in this conversion would be reaction with:

a. Mg/ether

b. PCC

c. oxiraneANS:b

11.The name of the product of the reaction of 2-chlorobutane with 1.) Li, 2.) CuI, 3.) 1-bromobutane would be _______________________.ANS:3-methylheptane

12.Consider the following reaction.

The name of the product that should be placed in the box is __________________.ANS:ethylcyclohexanePROBLEM


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BIAF 7eTest Bank17

ch15

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