Chapter 6 written questions
retention
If the absolute configuration at an asymmetric carbon does not change during the course of a reaction, the reaction is said to occur with ________ of stereochemistry.
2-chlorobutane < 2-iodobutane < 1-iodobutane
List the following alkyl halides in order of their increasing reactivity as substrates in SN2 reactions: 2-chlorobutane, 2-iodobutane, and 1-iodobutane.
1) Br2, hν 2) NaOCH3, CH3OH
110) Provide a series of synthetic steps by which (CH3)2C CH2 could be prepared from 2-methylpropane.
4-bromo-1,1 dimethylcyclohexane
19) Provide an acceptable name for the compound shown below.
CH3CH2CH2CH(CH3)CH2CH2Br
20) Provide the structure of 1-bromo-3-methylhexane.
CH3CH2F < CH3CH2Br < (CH3)2CHBr < CH3CH2CH2Br
29) Arrange the following alkyl halides in order of increasing boiling point: CH3CH2Br, CH3CH2CH2Br, (CH3)2CHBr, CH3CH2F
(CH3)2CHCH2CH2CH2I + CN- → (CH3)2CHCH2CH2CH2CH2CN + I-
39) Provide a detailed, stepwise mechanism for the reaction below.
polarizability
45) Name one factor that is favorable for nucleophilicity but not for basicity.
(CH3)3COH < (CH3)3CO- < CH3CH2O- < CH3CH2S-
46) Arrange the following species in order of increasing nucleophilicity: CH3CH2S-, CH3CH2O-, (CH3)3CO-, (CH3)3COH.
The iodide ion is the better nucleophile. The larger size of this ion renders its electron cloud more polarizable.
47) Which halide is a better nucleophile, iodide or fluoride? Explain.
methyl iodide < isopropyl chloride < t-butyl bromide < t-butyl iodide
Arrange the following compounds in order of increasing reactivity toward ethanol solvolysis: t-butyl bromide, t-butyl iodide, isopropyl chloride, methyl iodide.
2-bromo-2-methylpentane < 1-chloro-2,2-dimethylpentane < 1-chloro-3,3-dimethylpentane < bromoethane
Arrange the following substrates in order of their increasing SN2 reactivity with NaCN: bromoethane, 1-chloro-3,3-dimethylpentane, 1-chloro-2,2-dimethylpentane, and 2-bromo-2-methylpentane.
This is an SN2 reaction with a rate = k [(CH3)3CO-][CH3I]. The reaction rate will increase as [CH3I] increases.
Consider the reaction of (CH3)3CO- with iodomethane. Will the reaction rate increase, decrease, or remain the same if the concentration of iodomethane is increased? Explain.
Free Radical mechanism at the allylic C's
Draw two reasonable resonance structures and the hybrid of the intermediate formed in the following reaction.
chlorocyclopentane < iodocyclopentane < 1-iodo-1-ethylcyclopentane
List the following bromides in order of their increasing reactivity as substrates in SN1 reactions: 1-iodo-1-ethylcyclopentane, chlorocyclopentane, and iodocyclopentane.
1-iodobutane < 2-chlorobutane < 2-iodobutane
List the following bromides in order of their increasing reactivity as substrates in SN1 reactions: 2-chlorobutane, 2-iodobutane, and 1-iodobutane.
PhBr < PhCH2Br < PhCH(CH3)Br
List the following bromides in order of their increasing reactivity as substrates in SN1 reactions: PhBr, PhCH2Br, and PhCH(CH3)Br.
PhBr < PhCH(CH3)Br < PhCH2Br
List the following bromides in order of their increasing reactivity as substrates in SN2 reactions: PhBr, PhCH2Br, and PhCH(CH3)Br.
CH3Br < CH3CH2CH2I < CH3CHBrCH3 < CH3CHICH3 < (CH3)3CI
List the following compounds in order of increasing reactivity in an SN1 reaction. CH3Br, CH3CH2CH2I, (CH3)3CI, CH3CHBrCH3, CH3CHICH3
(3R,4R,6S)-4-ethyl-1,6-difluoro-3-methylheptane
Name the haloalkane shown. Be sure to include the appropriate R or S description if needed.
(S)- 3-chloro-1,1-dimethylcyclohexane
Name the haloalkane shown. Be sure to include the appropriate R or S description if needed.4
2-iodo-2-methylpentane
Provide an acceptable name for CH3CH2CH2C(CH3)2I.
chloroform
Provide an acceptable name for CHCl3.
cis-1, 2-dichlorocyclopentane
Provide an acceptable name for the compound shown below.
3-bromo-4-ethylheptane
Provide the name of the bromoalkane shown below.
(CH3)2CHIf
Provide the structure of isopropyl iodide.
H2O < CH3CO2- < HO- < CH3S-
Rank the species below in order of increasing nucleophilicity in hydroxylic solvents: CH3CO2-, CH3S-, HO-, H2O.
CH3I + NaOCH(CH3)2
Show the best way to prepare CH3OCH(CH3)2 by an SN2 reaction.
chlorofluorocarbon
The term CFC is an abbreviation for ________.
In elimination reactions, the most highly substituted alkene product is the major product.
What is Zaitsev's rule?
Polar, aprotic solvents are best. These solvents have strong dipole moments to enhance solubility of the anionic species but lack the ability to solvate the anion by hydrogen bonding.
What type of solvent is best for SN2 reactions which employ anionic nucleophiles: polar, protic solvents; polar, aprotic solvents; or nonpolar solvents? Explain.
Water is less dense than dichloromethane and therefore forms the upper phase.
When water is shaken with dichloromethane, a two-phase system results. Which compound forms the upper phase? Explain.
Ethoxide is the better nucleophile. The steric bulk of t-butoxide decreases its effectiveness as a nucleophile.
Which is more nucleophilic, t-butoxide or ethoxide? Explain.
The intermediate carbocation is resonance stabilized.
Why does CH2 CHCHBrCH3 undergo solvolysis much more rapidly than 2-bromobutane?
