1559T_ch08_132-14710/30/0511:59Pa9e140 ⊕ EQA 140.Chapter 8 HYDROXY FUNCTIONAL GROUP:ALCOHOLS:PROPERTIES,PREPARATION,AND STRATEGY OF SYNTHESIS eric interf redominant alcohol diastereome 33.To the right.H2 is a weaker acid than HO,and HO-is a weaker base than H- 34.(a)CH:CHDOH (b)CH,CHOD.from reaction of CH,CH2O with D' 假2 eiae,D, MgCI 35.(a)CHa(CH2)sCHCHs (b)CH:(CH2)sCHDCH ⊕ .0 (e)CHaCH2CH2MgCI 《 -CH2CH2CHs CH Li OHOH (h)CH;CCH2CH2CCH3 ◇◇ 37.Only the co wil Grignard reagent that forms:similarly,the terminal hydrogen on the alkyne function in (e)is acidic is about 25,alth em 4 not a problem,because it does not contain any acidic hydrogen atoms 140 • Chapter 8 HYDROXY FUNCTIONAL GROUP: ALCOHOLS: PROPERTIES, PREPARATION, AND STRATEGY OF SYNTHESIS (f ) Make a model. Here the main steric interference with hydride addition is by the axial hydrogens on the “top” side of the ring in the chair conformation: 33. To the right. H2 is a weaker acid than H2O, and HO
is a weaker base than H
. 34. (a) CH3CHDOH (b) CH3CH2OD, from reaction of CH3CH2O
with D (c) CH3CH2D, from SN2 reaction. (LiAlD4 serves as a source of “deuteride” nucleophile, D
, just as LiAlH4 is a source of hydride nucleophile, H
.) MgCl A 35. (a) CH3(CH2)5CHCH3 (b) CH3(CH2)5CHDCH3 (c) (d) (e) CH3CH2CH2MgCl (f ) (g) (h) 36. The desired reaction is CH3MgI C6H5CHO n CH3CH(OH)C6H5, a synthesis of a secondary alcohol by addition of a Grignard reagent to an aldehyde. The unexpected and undesired side reaction is the addition of methylmagnesium iodide to acetone: CH3MgI CH3COCH3 n (CH3)3COH, forming 2-methyl-2-propanol (tert-butyl alcohol). 37. Only the compounds pictured in parts (a) and (c) will form Grignard reagents in a problem-free manner. In (b) the OOH group contains an acidic hydrogen that will destroy the carbon–metal bond of any Grignard reagent that forms; similarly, the terminal hydrogen on the alkyne function in (e) is acidic enough to do the same (the pKa is about 25, although all you need to know—from the information in Problem 42 of Chapter 1Ois that such hydrogens are much more acidic than hydrogens on alkane carbons). Finally, in (d) the carbonyl function contains a strongly electrophilic carbon and will interfere. The ether function in (c) is not a problem, because it does not contain any acidic hydrogen atoms. OH OH CH3CCH2CH2CCH3 Li CH2CH2CH3 CH3 OH C HO Li H H H H H H O H HO H H H Less hindered Predominant alcohol diastereomer Hindered 1559T_ch08_132-147 10/30/05 11:59 Page 140