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Solutions for Structure and Synthesis of Alcohols
21 continued
Br
Br
Li CuI
Li CuI
CuLi
CuLi
I
I
(c)
2
2
(d)
Alternatively, coupling lithium dicyclohexylcuprate with 1-bromobutane would also work. As 
this mechanism is not a typical SN2, it is not as susceptible to steric hindrance like acetylide ion 
substitution or a similar SN2 reaction.
H BrMg C C CH2CH3
D
 + Mg(OD)Br
(e)
(a)
22 These reactions are acid-base reactions in which an acidic proton (or deuteron) is transferred to a 
basic carbon in either a Grignard reagent or an alkyllithium.
(d)(c)
+
D (b) CH3CH2CH2CH3 + LiOCH2CH3+ Mg(OD)I
OCH3
O
OH
HO
O
O OH
OH
(a) As Grignard reagent is formed, it would instantaneously be protonated by the N—H present in other 
molecules of the same substance.
(b) As Grignard reagent is formed, it would immediately attack the ester functional group present in other 
molecules of the same substance.
(c) Care must be taken in how reagents are written above and below arrows. If reagents are numbered 
"1. ... 2. ... etc.", it means they are added in separate steps, the same as writing reagents over separate 
arrows. If reagents written around an arrow are not numbered, it means they are added all at once in the 
same mixture. In this problem, the ketone is added in the presence of aqueous acid. The acid will 
immediately protonate and destroy the Grignard reagent before reaction with the ketone can occur.
(d) The ethyl Grignard reagent will be immediately protonated and consumed by the OH. This reaction 
could be made to work, however, by adding two equivalents of ethyl Grignard reagent: the first to consume 
the OH proton, the second to add across the ketone. Aqueous acid will then protonate both oxygens.
23 Grignard reagents are incompatible with acidic hydrogens and with electrophilic, polarized multiple 
bonds like C=O, NO2, etc.
acid work-up)
(PhCOO– before(b) no reaction
(e)
(c) no reaction(a) CH3(CH2)8CH2OH
24 Sodium borohydride does not reduce carboxylic acids or esters.
(d)
(f) ester
OH
OH
HO
HO
HO OH
OH
+ HOCH3
(a) CH3(CH2)8CH2OH
25 Lithium aluminum hydride reduces carboxylic acids and esters as well as other carbonyl groups.
(c) PhCH2OH(b) CH3CH2CH2OH + HOCH3
(e) (f)
(d)
O
O– Li+H3C
+
231