Organic Chemistry 2 · Functional-group transformations
Alcohol transformations: practice problems
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- Tosylation of cyclohexanol with TsCl and pyridine
- Electron accounting with an ionic base
- Replacing the group on a primary carbon
- A tertiary alcohol substitution branch
- Alcohol dehydration — propan-2-ol to propene
- Follow a rearranged dehydration branch
- Pinacol rearrangement — methyl migration to pinacolone
- Epoxide opening with a methyl shift and inversion
- Protect an alcohol by acyl transfer
Draw the mechanism 94
- Electron accounting with an ionic baseShow O–H deprotonation and H–H bond formation without breaking C–O.
- Replacing the group on a primary carbonActivate an alcohol and perform concerted nucleophilic displacement.
- A tertiary alcohol substitution branchDistinguish tertiary alcohol ionization from primary SN2 replacement and retain the water byproduct.
- Alcohol dehydration — propan-2-ol to propeneProtonate the alcohol, let water leave, then remove a neighboring proton to form the alkene and regenerate the acid.
- Follow a rearranged dehydration branchKeep hydride migration distinct from beta proton loss while following a specified minor-product connectivity.
- Pinacol rearrangement — methyl migration to pinacoloneCouple a 1,2-carbon migration to carbonyl formation in a complete pinacol rearrangement.
- Epoxide opening with a methyl shift and inversionFollow acid-activated epoxide opening coupled to a 1,2-methyl shift (a semipinacol, Meinwald-type rearrangement) and follow inversion at the migration terminus.
- Protect an alcohol by acyl transferDistinguish neutral alcohol acylation from alkoxide attack and account for the acid-scavenging base.
- Activate oxygen without breaking carbon–oxygenTrack sulfonyl substitution and base capture while retaining the original alcohol C–O bond.
- Alcohol to alkyl bromide — PBr₃Bond the alcohol oxygen to phosphorus, then use bromide for an SN2 attack at carbon.
- Williamson ether synthesis — alcohol activation and allylationRemove the alcohol proton, then form an ether by SN2 attack next to the alkene.
- A neutral alcohol traps an alcohol-derived cationContrast SN1 etherification with Williamson synthesis and account for the neutral nucleophile proton.
- Dehydrate without a primary carbocationCoordinate beta proton loss with departure of activated hydroxyl in a primary-alcohol elimination.
- PBr3 converts 3-methylbutan-2-ol to 2-bromo-3-methylbutaneDraw the alcohol oxygen attacking PBr3 and expelling bromide, then the bromide SN2 at the carbinol carbon that releases HOPBr2, giving 2-bromo-3-methylbutane without rearrangement.
- POCl3/pyridine dehydration of cis-2-methylcyclohexan-1-olDraw conversion of cis-2-methylcyclohexan-1-ol into its dichlorophosphate ester, deprotonation by pyridine, and the E2 in which pyridine removes the hydrogen on the methyl-bearing carbon, giving 1-methylcyclohexene.
- SOCl2/pyridine converts 3-methylbutan-2-ol to 2-chloro-3-methylbutaneDraw formation of the alkyl chlorosulfite from 3-methylbutan-2-ol, its deprotonation by pyridine, and the chloride SN2 that releases SO2 and chloride, giving 2-chloro-3-methylbutane.
- Tosylation of cyclohexanol with TsCl and pyridineDraw cyclohexanol attacking the sulfur of tosyl chloride with loss of chloride, then pyridine removing the O–H proton to give cyclohexyl tosylate.
- Acetonide of cis-cyclohexane-1,2-diol with acetone and TsOHDraw the TsOH-catalysed protection of cis-cyclohexane-1,2-diol as its acetonide: hemiketal formation, loss of water to an oxocarbenium ion and ring closure by the second OH.
- Ethyl acetate from ethanol and acetic anhydrideDraw acetylation of ethanol by acetic anhydride: addition to a carbonyl, collapse of the tetrahedral intermediate expelling acetate, and deprotonation by pyridine.
- (3-Bromopropyl)benzene by Appel brominationDraw the Appel bromination of 3-phenylpropan-1-ol: bromophosphonium formation, deprotonation by the tribromomethanide anion, the alkoxyphosphonium ion, and SN2 by bromide to (3-bromopropyl)benzene.
- (R)-(2-Chloropropyl)benzene by Appel chlorinationDraw the Appel chlorination of (S)-1-phenylpropan-2-ol: chlorophosphonium formation, deprotonation, the alkoxyphosphonium ion, and the inverting SN2 by chloride that gives (R)-(2-chloropropyl)benzene.
- Benzyl cyclohexyl ether by Williamson synthesisDraw the benzyl protection of cyclohexanol: deprotonation by sodium hydride to the alkoxide and SN2 attack of cyclohexoxide on benzyl bromide to give [(cyclohexyloxy)methyl]benzene.
- 1-Ethylcyclopentene from 1-Ethylcyclopentanol (H3PO4)Draw the phosphoric acid dehydration of 1-ethylcyclopentanol and decide which β-hydrogen is lost to give 1-ethylcyclopentene.
- 1-Methylcyclopentene from (1-methylcyclobutyl)methanolDraw protonation of (1-methylcyclobutyl)methanol, the ring bond migration that expands the four-membered ring to a tertiary cyclopentyl cation as water leaves, and Zaitsev proton loss to 1-methylcyclopentene.
- 1-Methylcycloheptene from 1-Methylcycloheptanol (E1)Draw the E1 dehydration of 1-methylcycloheptanol in hot sulfuric acid through its tertiary carbocation to 1-methylcycloheptene.
- Dehydrating a tertiary ring alcoholDraw the E1 dehydration of 1-methylcyclohexanol in hot sulfuric acid through its tertiary carbocation to 1-methylcyclohexene.
- 1-Phenylcyclohexene from 1-Phenylcyclohexanol (E1)Draw the phosphoric acid dehydration of 1-phenylcyclohexanol through its tertiary benzylic cation to 1-phenylcyclohexene.
- Styrene from 1-phenylethanolDraw the E1 dehydration of 1-phenylethanol to styrene: protonation, loss of water to the benzylic cation, and loss of a methyl proton.
- (E)-1-Phenylpropene from 1-Phenylpropan-1-ol (TsOH)Draw the TsOH-catalysed dehydration of 1-phenylpropan-1-ol through its benzylic cation to the conjugated (E)-1-phenylpropene.
- 1,2-Dimethylcyclohexene from 2,2-dimethylcyclohexan-1-olDraw protonation, loss of water, the 1,2-methyl shift and the E1 deprotonation that turn 2,2-dimethylcyclohexan-1-ol into 1,2-dimethylcyclohexene.
- 2-Methyl-1-phenylprop-1-ene by E1 DehydrationDraw the E1 dehydration of 2-methyl-1-phenylpropan-2-ol and choose the β-hydrogen whose loss gives the conjugated 2-methyl-1-phenylprop-1-ene.
- Zaitsev dehydration of 2-methylcyclohexanolDraw the acid-catalysed E1 dehydration of 2-methylcyclohexanol and explain why the trisubstituted alkene 1-methylcyclohexene is the major product.
- 2,3-Dimethylbut-2-ene from 3,3-dimethylbutan-2-olDraw protonation, loss of water, the methyl shift to a tertiary cation and the deprotonation that gives 2,3-dimethylbut-2-ene from 3,3-dimethylbutan-2-ol.
- 3-Ethylpent-2-ene from 3-Ethylpentan-3-ol (E1)Draw the E1 dehydration of 3-ethylpentan-3-ol in hot sulfuric acid and see why only one alkene, 3-ethylpent-2-ene, can form.
- Ring expansion: cyclobutylmethanol to cyclopenteneDraw protonation of cyclobutylmethanol, the alkyl shift that expands the four-membered ring as water leaves, and loss of a proton to give cyclopentene.
- Cyclohexene from cyclohexanol in hot acidDraw the acid-catalysed E1 dehydration of cyclohexanol, from protonation through loss of water to deprotonation, giving cyclohexene.
- (E)-Pent-2-ene from Pentan-2-ol by Acid DehydrationDraw the E1 dehydration of pentan-2-ol in hot sulfuric acid and explain why (E)-pent-2-ene is the major alkene.
- Diethyl ether from ethanolDraw the acid-catalysed condensation of two ethanol molecules to diethyl ether: protonation, SN2 displacement of water by a second ethanol, and deprotonation.
- 1-Bromo-1-ethylcyclohexane from 1-CyclohexylethanolShow how the secondary cation from 1-cyclohexylethanol takes a hydride from the ring so that bromide ends up on the ring carbon of 1-bromo-1-ethylcyclohexane.
- Benzylic alcohol to benzylic bromideDraw the SN1 conversion of 1-phenylethanol to (1-bromoethyl)benzene and explain why the secondary benzylic cation forms easily.
- Prenyl Bromide from 2-Methylbut-3-en-2-ol and HBrShow how the allylic cation from 2-methylbut-3-en-2-ol is trapped by bromide at the primary end to give 1-bromo-3-methylbut-2-ene.
- Hydride shift during HBr substitutionFollow 3-methylbutan-2-ol through protonation, ionization, a 1,2-hydride shift and bromide capture to the rearranged tertiary bromide.
- 3-Bromo-3-methylpentane from 3-Methylpentan-2-olFollow 3-methylpentan-2-ol through protonation, loss of water, a 1,2-hydride shift from C3 and bromide capture to 3-bromo-3-methylpentane.
- Allyl Bromide from Allyl Alcohol by SN2 with HBrDraw the SN2 conversion of allyl alcohol to allyl bromide with cold aqueous HBr, from the protonated alcohol to backside attack by bromide.
- Benzyl Bromide from Benzyl Alcohol and Hot HBrDraw the SN1 conversion of benzyl alcohol to benzyl bromide and explain why a primary benzylic alcohol can ionize.
- Allylic rearrangement with HBrShow how the allyl cation from but-3-en-2-ol is trapped by bromide at the far end to give (E)-1-bromobut-2-ene.
- Primary alcohol to primary bromide with HBrShow why a primary alcohol reacts with hot HBr by protonation followed by one-step backside displacement of water (butan-1-ol).
- 2-Bromo-2-methylbutane from Neopentyl Alcohol and HBrShow why neopentyl alcohol with hot HBr gives 2-bromo-2-methylbutane: a methyl group migrates as water leaves, so no primary cation ever forms.
- 2-Bromo-2-methylpropane from tert-butyl alcoholConvert a tertiary alcohol to a tertiary alkyl bromide with HBr by protonation, ionization and bromide capture (2-methylpropan-2-ol).
- 1-Chloro-1-methylcyclohexane from 1-MethylcyclohexanolConvert 1-methylcyclohexanol to 1-chloro-1-methylcyclohexane with concentrated HCl, showing the oxonium ion and the tertiary ring carbocation.
- 2-Chloro-2-methylbutane from 2-Methylbutan-2-ol (SN1)Draw the SN1 reaction of 2-methylbutan-2-ol with concentrated HCl at room temperature through the tertiary cation to 2-chloro-2-methylbutane.
- trans-2-Methylcyclohexan-1-ol by hydroboration–oxidationDraw syn hydroboration of 1-methylcyclohexene, addition of hydroperoxide to boron, the alkyl shift from boron to oxygen, and hydrolysis to trans-2-methylcyclohexan-1-ol.
- Oxane from 5-chloropentan-1-olDraw the deprotonation of 5-chloropentan-1-ol by sodium hydride and the intramolecular SN2 that closes the six-membered ring of oxane.
- Lucas reagent on butan-2-olDraw how ZnCl2 activates butan-2-ol so that chloride from HCl can trap a secondary carbocation, the basis of the Lucas test.
- Phenylacetaldehyde from styrene oxide (Meinwald)Draw the BF3-promoted Meinwald rearrangement of styrene oxide: coordination of the oxygen to boron, opening at the benzylic carbon, a 1,2-hydride shift with C=O formation, and release of BF3 to give 2-phenylacetaldehyde.
- Pinacolone from tetramethyloxirane by Meinwald rearrangementDraw the BF3-promoted Meinwald rearrangement of tetramethyloxirane: oxygen coordination to boron, ring opening to a tertiary cation, a 1,2-methyl shift with C=O formation, and release of BF3 to give pinacolone.
- Cyclohexyl mesylate via sulfeneDraw the sulfene pathway by which triethylamine and methanesulfonyl chloride convert cyclohexanol into cyclohexyl mesylate.
- trans-4-tert-Butylcyclohexyl 4-nitrobenzoate by MitsunobuDraw the Mitsunobu esterification of cis-4-tert-butylcyclohexan-1-ol with 4-nitrobenzoic acid: PPh3 addition to DIAD, the proton transfers, the axial alkoxyphosphonium ion, and the inverting SN2 that gives the trans ester.
- (S)-Butan-2-yl benzoate by Mitsunobu inversionDraw the Mitsunobu esterification of (R)-butan-2-ol with benzoic acid: PPh3 addition to DEAD, proton transfers, the alkoxyphosphonium ion, and the inverting SN2 by benzoate.
- Cyclohexanol from its MOM ether with HCl in methanolDraw the acid-catalysed cleavage of (methoxymethoxy)cyclohexane in methanol: protonation, loss of cyclohexanol to the methoxymethyl cation and its capture by methanol.
- Cyclohexyl MOM ether from cyclohexanol and MOMClDraw the MOM protection of cyclohexanol: ionization of chloromethyl methyl ether to the oxocarbenium ion, attack by the alcohol oxygen, and deprotonation by Hünig's base to give (methoxymethoxy)cyclohexane.
- 1-Methylcyclohexan-1-ol by oxymercuration–demercurationDraw the oxymercuration of 1-methylcyclohexene (mercury electrophile, water attack at the tertiary carbon, deprotonation) and the NaBH4 replacement of mercury by hydrogen to give 1-methylcyclohexan-1-ol.
- (Bromomethyl)cyclopentane from Cyclopentylmethanol (PBr3)Convert cyclopentylmethanol to (bromomethyl)cyclopentane with PBr3 and explain why no ring-expanded product forms.
- (R)-2-Bromopentane from (S)-pentan-2-olDraw O–P bond formation and the backside bromide attack that converts (S)-pentan-2-ol into (R)-2-bromopentane without rearrangement.
- cis-1-Bromo-4-tert-butylcyclohexane by PBr3 InversionShow how PBr3 and pyridine turn trans-4-tert-butylcyclohexanol into cis-1-bromo-4-tert-butylcyclohexane by axial backside attack on the activated equatorial oxygen.
- 3,3-Diphenylbutan-2-one by pinacol rearrangementDraw the pinacol rearrangement of 2-methyl-1,1-diphenylpropane-1,2-diol: ionization at the diphenyl carbon, a 1,2-methyl shift, and deprotonation of the oxocarbenium ion to 3,3-diphenylbutan-2-one.
- 3-Methyl-3-phenylbutan-2-one by pinacol rearrangementDraw the pinacol rearrangement of 2-methyl-3-phenylbutane-2,3-diol: protonation of the benzylic OH, loss of water, a 1,2-methyl shift, and deprotonation of the oxocarbenium ion to 3-methyl-3-phenylbutan-2-one.
- Spiro[5.6]dodecan-7-one from bicyclohexyl-1,1′-diolDraw the ring-expanding pinacol rearrangement of [1,1′-bi(cyclohexane)]-1,1′-diol to spiro[5.6]dodecan-7-one: protonation, loss of water, ring-bond migration and deprotonation.
- 2,2-Diphenylacetaldehyde from hydrobenzoinDraw the pinacol rearrangement of hydrobenzoin: protonation, loss of water, phenyl migration, and deprotonation of the oxocarbenium ion to 2,2-diphenylacetaldehyde.
- 1-Phenylcyclohexene from cis-2-Phenylcyclohexanol (POCl3)Show how POCl3 and pyridine dehydrate cis-2-phenylcyclohexanol by E2, removing the benzylic hydrogen that is trans-diaxial to the leaving group.
- 3,3-Dimethylbut-1-ene from 3,3-dimethylbutan-2-ol with POCl3Draw the POCl3/pyridine dehydration of 3,3-dimethylbutan-2-ol: formation of the dichlorophosphate ester, deprotonation by pyridine, and the E2 elimination that gives 3,3-dimethylbut-1-ene without a methyl shift.
- 3-Methylcyclohexene from trans-2-methylcyclohexan-1-olDraw conversion of trans-2-methylcyclohexan-1-ol into its dichlorophosphate, deprotonation by pyridine, and the anti-periplanar E2 that gives 3-methylcyclohexene.
- 2-Methylpropanal from 2-methylpropane-1,2-diolDraw the acid-catalysed pinacol rearrangement of 2-methylpropane-1,2-diol: ionization of the tertiary OH, a 1,2-hydride shift that forms the protonated aldehyde, and deprotonation to 2-methylpropanal.
- 2,2-Diphenylcyclohexanone by pinacol ring expansionDraw the pinacol ring expansion of 1-(hydroxydiphenylmethyl)cyclopentan-1-ol: ionization at the diphenyl carbon, migration of a ring bond that grows the ring to six carbons, and deprotonation to 2,2-diphenylcyclohexan-1-one.
- Retention with SOCl2 and no baseDraw chlorosulfite formation from (R)-butan-2-ol and the internal front-side chlorine delivery (SNi) that gives (R)-2-chlorobutane with retention.
- (2-Chloroethyl)benzene from 2-Phenylethanol and SOCl2Draw how thionyl chloride and pyridine convert 2-phenylethanol to (2-chloroethyl)benzene through an alkyl chlorosulfite and SN2 attack by chloride.
- (S)-(3-Chlorobutyl)benzene from (R)-4-Phenylbutan-2-olDraw how SOCl2 and pyridine turn (R)-4-phenylbutan-2-ol into (S)-(3-chlorobutyl)benzene through a chlorosulfite ester and backside attack by chloride.
- (S)-2-Chlorobutane from (R)-butan-2-olDraw chlorosulfite formation from (R)-butan-2-ol and the backside chloride attack that gives (S)-2-chlorobutane with inversion.
- Solketal from glycerol and acetone with TsOHDraw the TsOH-catalysed formation of solketal from glycerol and acetone, and explain why the 1,2-diol forms a five-membered acetonide.
- Ethanol from its TBS ether with TBAFDraw fluoride removal of the TBS group from tert-butyldimethyl(ethoxy)silane and the protonation of ethoxide in the aqueous workup.
- tert-Butyldimethyl(ethoxy)silane from ethanolDraw protection of ethanol as its TBS ether: substitution of chloride at silicon by the alcohol oxygen and removal of the O–H proton by imidazole.
- TBS ether of 1-methylcyclohexanol with TBSOTf and lutidineDraw the silylation of the tertiary alcohol 1-methylcyclohexanol with TBSOTf: substitution at silicon with loss of triflate, then deprotonation by 2,6-lutidine.
- tert-Butyl methyl ether by Williamson synthesisDraw deprotonation of tert-butyl alcohol by sodium hydride and the SN2 attack of tert-butoxide on iodomethane to give tert-butyl methyl ether.
- 2-Ethoxyoxane from ethanol and dihydropyranDraw the PPTS-catalysed formation of the THP ether: protonation of 3,4-dihydro-2H-pyran to the oxocarbenium ion, addition of ethanol, and deprotonation by pyridine.
- Tiffeneau–Demjanov expansion to cycloheptanoneDraw the Tiffeneau–Demjanov reaction of 1-(aminomethyl)cyclohexan-1-ol: diazotization with the nitrosonium ion, loss of N2 with migration of a ring bond, and deprotonation to cycloheptanone.
- Tiffeneau–Demjanov expansion to cyclohexanoneDraw the Tiffeneau–Demjanov reaction of 1-(aminomethyl)cyclopentan-1-ol: diazotization with the nitrosonium ion, loss of N2 with migration of a ring bond, and deprotonation to cyclohexanone.
- (S)-Octan-2-yl acetate from (R)-octan-2-yl tosylateDraw the SN2 displacement of tosylate from (R)-octan-2-yl tosylate by acetate in DMF and assign the inverted configuration of (S)-octan-2-yl acetate.
- Cyclohexene via cyclohexyl tosylateDraw tosylation of cyclohexanol and the concerted E2 of cyclohexyl tosylate with potassium tert-butoxide that forms cyclohexene.
- Tosylate then cyanide on (R)-butan-2-olTrack the stereocentre of (R)-butan-2-ol through tosylation with retention and cyanide displacement with inversion to (S)-2-methylbutanenitrile.
- (R)-2-Iodopentane from (S)-pentan-2-yl tosylate and NaIDraw the SN2 displacement of tosylate from (S)-pentan-2-yl tosylate by iodide in acetone and assign the inverted configuration of (R)-2-iodopentane.
- Isobutyl tosylate from 2-methylpropan-1-ol and TsClDraw the tosylation of 2-methylpropan-1-ol: attack of the alcohol oxygen on the sulfur of TsCl with loss of chloride, then deprotonation by pyridine to give 2-methylpropyl 4-methylbenzenesulfonate.
- 2-Hydroxypropyl tosylate from propane-1,2-diolDraw the selective tosylation of propane-1,2-diol at the primary OH: attack of the primary oxygen on TsCl with loss of chloride, then deprotonation by pyridine to give 2-hydroxypropyl 4-methylbenzenesulfonate.
- 2-Phenylethyl triflate from 2-phenylethanol and Tf2ODraw the triflation of 2-phenylethan-1-ol: attack of the alcohol oxygen on a sulfur of triflic anhydride with loss of triflate, then removal of the O–H proton by pyridine to give 2-phenylethyl triflate.
- Selective trityl ether of butane-1,3-diol at the primary OHDraw the selective tritylation of butane-1,3-diol: ionization of trityl chloride to the trityl cation, capture by the primary OH and deprotonation by pyridine.
Predict the product 17
- Follow the oxygen atomUse isotopic labeling to distinguish O–H exchange from C–O cleavage.
- Dehydration of cyclobutylmethanol with ring expansionPredict the product of an acid-catalysed dehydration in which a strained ring expands.
- Major alkene from 2-methylbutan-2-ol in hot acidPredict the major alkene from acid-catalysed dehydration of a tertiary alcohol using the Zaitsev rule.
- Ethyl acetate from ethanol and acetic acid with acidPredict the ester formed when an alcohol is heated with a carboxylic acid and an acid catalyst.
- HBr on 2-methylpropan-2-ol: predict the bromidePredict the product of HBr with a tertiary alcohol through an SN1 pathway.
- Methylmagnesium bromide opens ethylene oxidePredict the alcohol formed when a Grignard reagent opens an epoxide.
- NaBH4 on methyl 4-oxopentanoateUse the reactivity gap between ketones and esters to predict a selective NaBH4 reduction.
- PCC on 2-methylpentane-2,4-diol: which OH reacts?Use the carbinol C–H requirement to predict which OH of a diol is oxidized.
- Jones oxidation of pentan-1-olPredict how far aqueous chromic acid oxidizes a primary alcohol.
- PCC oxidation of pentan-1-olPredict the oxidation level reached when a primary alcohol meets anhydrous PCC.
- Dichromate oxidation of cyclohexanolPredict the product of oxidizing a secondary alcohol with aqueous chromic acid.
- Configuration after PBr3 on (S)-pentan-2-olPredict the configuration of the alkyl bromide formed when a chiral secondary alcohol reacts with PBr3.
- Periodic acid cleavage of cyclohexane-1,2-diolPredict the carbonyl products of periodic acid cleavage of a cyclic 1,2-diol.
- Pinacol in sulfuric acid: predict the ketonePredict the carbonyl product of a pinacol rearrangement of a symmetrical 1,2-diol.
- SOCl2 and pyridine on (R)-butan-2-ol: which stereochemistry?Predict the configuration of the alkyl chloride formed from a chiral secondary alcohol with SOCl2 and pyridine.
- Tosylation of (R)-octan-2-ol: configuration keptPredict the configuration of a sulfonate ester formed from a chiral alcohol with TsCl and pyridine.
- Cyanide on (R)-octan-2-yl tosylate: which nitrile?Predict the stereochemistry of the nitrile formed when cyanide displaces a secondary tosylate.
Classify 8
- Read the alcohol carbonClassify an alcohol and predict its non-cleaving oxidation product.
- 1°, 2°, 3°Classify an alcohol by the number of carbons on the carbinol carbon.
- E1 or E2 dehydration for each alcohol classClassify acid-catalysed alcohol dehydrations as E1 or E2 based on the degree of the alcohol carbon.
- Name the alcoholPick the structure of 3-methylbutan-2-ol from its IUPAC name.
- Ring alcohol stereoName a disubstituted cyclohexanol with ring numbering and cis/trans.
- Name a diolName a diol with locants and the retained -e of the alkane.
- OH outranks alkeneNumber a chain so the hydroxyl, not the alkene, gets the lowest locant.
- Which oxidants stop a primary alcohol at the aldehyde?Classify common oxidants by the oxidation level they reach with a primary alcohol.
Compare 4
- Compare proposed leaving groupsRelate leaving-group ability to protonation of hydroxyl.
- Rank alcohol acidityRank alcohols by acidity using induction and solvation of the alkoxide.
- Dehydration rate: three pentanol isomersRank alcohols by their ease of acid-catalysed dehydration from the stability of the cationic intermediate.
- Lucas test speed: butanol isomersRank alcohols by Lucas test speed from the stability of the carbocation each one forms.
Calculate 1
- Periodic acid equivalents for glycerolCount the equivalents of periodic acid consumed by a polyol from its C–C bonds between OH-bearing carbons.
Find the error 2
- Audit a dehydration proposalRecognize hydride rearrangement after acid-promoted water loss.
- HBr on 3-methylbutan-2-ol: will it rearrange?Diagnose when an alcohol-to-halide reaction with HBr gives a rearranged product through a hydride shift.
Interpret the evidence 1
- Separate activation from displacementCombine retention in O-sulfonylation with inversion in SN2 displacement.
Work backward 2
- Work backward from dehydrationIdentify an alcohol precursor using carbon connectivity.
- Grignard route to 2-phenylbutan-2-olDisconnect a tertiary alcohol into a Grignard reagent and a ketone.
Plan a synthesis 7
- Choose a stopping pointSelect conditions that stop a primary-alcohol oxidation at an aldehyde.
- Make the alkoxideChoose a base that converts an alcohol completely to its alkoxide.
- cis- and trans-Cyclohexane-1,2-diol from cyclohexeneChoose reagents that give either the cis or the trans 1,2-diol from the same cycloalkene.
- Anti-Markovnikov alcohol from 1-methylcyclohexenePredict the regiochemistry and stereochemistry of hydroboration–oxidation of a trisubstituted cyclic alkene.
- Markovnikov alcoholChoose reagents that add water across an alkene with Markovnikov regiochemistry.
- Protecting 4-bromobutan-1-ol before a Grignard stepChoose a protecting group for an alcohol that survives a Grignard reagent and can be removed afterwards.
- Methoxycyclohexane from cyclohexanol: Williamson planChoose the alkoxide and alkyl halide pairing for a Williamson ether synthesis that avoids elimination.
Explain why 6
- Locate the missing hydrogenExplain the boundary of ordinary alcohol-to-carbonyl oxidation.
- Why alcohols boil higherExplain the boiling-point gap between an alcohol and an isomeric ether.
- Why POCl3 and pyridine for 3,3-dimethylbutan-2-olExplain why POCl3 and pyridine dehydrate an alcohol without carbocation rearrangement.
- Why make a mesylate or tosylate from an alcoholExplain why alcohols are converted to mesylates or tosylates before substitution or elimination.
- pKa 10 vs 16Explain why phenol is about a million times more acidic than cyclohexanol.
- Pinacol shift in 1,1-diphenyl-2-methylpropane-1,2-diolDecide which group migrates in an unsymmetrical pinacol rearrangement by first finding the more stable carbocation.
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