CHAPTER FIFTEEN Alcohols, Diols, and Thiols Ketones yield secondary alcohols: RCR′+H P, Pd, Ni, or R RCHR′ Ketone Secondary alcohol Cyclopentanone Cyclopentanol (93-95%) TPROBLEM 15.1 Which of the isomeric CaH1oo alcohols can be prepared by hydrogenation of aldehydes? Which can be prepared by hydrogenation of stones? Which cannot be prepared by hydrogenation of a carbonyl compound For most laboratory-scale reductions of aldehydes and ketones, catalytic hydro- genation has been replaced by methods based on metal hydride reducing agents. The two most common reagents are sodium borohydride and lithium aluminum hydride H the electrostatic laps of CHa, BH Na*H-B=H Li*H-AI-H ice how different the H lectrostatic potentials associ- ted with hydrog Sodium borohydride(NaBH4) Lithium aluminum hydride (LiAlH4) Sodium borohydride is especially easy to use, needing only to be added to an aque- ous or alcoholic solution of an aldehyde or a ketone: water. methanol RCHO Aldehyde O,N m-Nitrobenzaldehyde m-Nitrobenzyl alcohol (82%o) RCR RCHR Ketone or ethanol Secondary alcohol OH CH3CCH,C(CH3)3 CH3CHCH, C(CH3)3 4, 4-Dimethy l-2-pentanone 4. 4-Dimethy l-2-pentanol(85%) Back Forward Main MenuToc Study Guide ToC Student o MHHE WebsiteKetones yield secondary alcohols: PROBLEM 15.1 Which of the isomeric C4H10O alcohols can be prepared by hydrogenation of aldehydes? Which can be prepared by hydrogenation of ketones? Which cannot be prepared by hydrogenation of a carbonyl compound? For most laboratory-scale reductions of aldehydes and ketones, catalytic hydro￾genation has been replaced by methods based on metal hydride reducing agents. The two most common reagents are sodium borohydride and lithium aluminum hydride. Sodium borohydride is especially easy to use, needing only to be added to an aque￾ous or alcoholic solution of an aldehyde or a ketone: NaBH4 methanol O2N CH O m-Nitrobenzaldehyde CH2OH O2N m-Nitrobenzyl alcohol (82%) NaBH4 water, methanol, or ethanol RCH O Aldehyde RCH2OH Primary alcohol NaBH4 water, methanol, or ethanol RCR O Ketone RCHR OH Secondary alcohol CH3CCH2C(CH3)3 O 4,4-Dimethyl-2-pentanone CH3CHCH2C(CH3)3 OH 4,4-Dimethyl-2-pentanol (85%) NaBH4 ethanol Sodium borohydride (NaBH4) Na H±B±H H W W H  Li H±Al±H H W W H  Lithium aluminum hydride (LiAlH4) RCR O Ketone H2 Hydrogen Pt, Pd, Ni, or Ru RCHR OH Secondary alcohol H2, Pt methanol O Cyclopentanone H OH Cyclopentanol (93–95%) 584 CHAPTER FIFTEEN Alcohols, Diols, and Thiols Compare the electrostatic potential maps of CH4, BH4 , and AlH4  on Learning By Mod￾eling. Notice how different the electrostatic potentials associ￾ated with hydrogen are. Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website