Explain why the acid-catalyzed condensation is a poor

Classify each reaction as an oxidation, a reduction, or neither.

Problem 2P Predict the products of the reactions of the following compounds with chromic acid and also with PCC. (a) cyclohexanol (b) 1-methylcyclohexanol (c) cyclopentylmethanol (d) cyclohexanone (e) cyclohexane (f) acetic acid, CH3COOH (g) ethanol (h) acetaldehyde, CH3CHO

Problem 3P We have covered several oxidants that use a multi-valent atom (Cr, Cl, S, or I) as their active species, going from a higher oxidation state before the oxidation to a lower oxidation state after oxidizing the alcohol. Draw the structure of the following atoms, before and after the oxidation of an alcohol to a ketone or aldehyde. How many bonds to oxygen does each atom have before and after the oxidation? (a) the Cr in chromic acid (b) the Cl in sodium hypochlorite (c) the S in the Swern oxidation (d) the I in the DMP reagent (e) the carbinol C in the alcohol that is oxidized

Give the structure of the principal product(s) when each of the following alcohols reacts with (1) \(\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} / \mathrm{H}_{2} \mathrm{SO}_{4}\) (2) \(\text { PCC, }\) (3) \(\text { DMP }\) (4) \(\text { NaOCl. }\) (a) octan-1-ol (b) octan-3-ol (c) 4-hydroxydecanal (d) 1-methylcyclohexanol Equation Transcription: Text Transcription: Na_2Cr_2O_7/H_2SO_4 PCC DMP NaOCI

Problem 11P Predict the products of the following reactions. (a) cyclohexylmethanol + TsCl / pyridine (b) product of (a) + LiAIH4 (c) 1-methylcyclohexanol + H2SO4, heat (d) product of (c) +H2,Pt

Problem 10P Show how you would convert propan-1-ol to the following compounds using tosylate intermediates. You may use whatever additional reagents are needed. (a) 1-bromopropane (b) propan-1-amine, CH3CH2CH2NH2 (c)CH3CH2CH2OCH2CH3 ethyl propyl ether (d) CH3CH2CH2CN butyronitrile

Problem 12P Propose a mechanism for the reaction of (a) 1-methylcyclohexanol with HBr to form 1-bromo-1-methylcyclohexane. (b) 2-cyclohexylethanol with HBr to form 1-bromo-2-cyclohexylethane.

Problem 13P The reaction of tert-butyl alcohol with concentrated HCl goes by the SN1 mechanism. Write a mechanism for this reaction.

Problem 14P Show how you would use a simple chemical test to distinguish between the following pairs of compounds. Tell what you would observe with each compound. (a) isopropyl alcohol and tert-butyl alcohol (b) isopropyl alcohol and butan-2-one,CH3COH2CH3 (c) hexan-1-ol and cyclohexanol (d) allyl alcohol and propan-1-ol (e) butan-2-one and tert-butyl alcohol

Neopentyl alcohol, \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCH}_{2} \mathrm{OH}\), reacts with concentrated \(H B r\) to give 2-bromo-2-methylbutane, a rearranged product. Propose a mechanism for the formation of this product. Equation Transcription: Text Transcription: (CH_3)_3CCH_2OH HBr

Explain the products observed in the following reaction of an alcohol with the Lucas reagent. Equation Transcription: Text Transcription: CH_3 CH_3 OH HCI/ZnCI_2 CH_3 CH_3 CI CH_3 CI CH_3

Write balanced equations for the three preceding reactions.

Problem 17P When cis-2-methylcyclohexanol reacts with the Lucas reagent, the major product is 1-chloro- 1-methylcyclohexane. Propose a mechanism to explain the formation of this product.

Problem 19P Suggest how you would convert trans-4-methylcyclohexanol to (a) trans-1-chloro-4-methylcyclohexane. (b) cis-1-chloro-4-methylcyclohexane.

Two products are observed in the following reaction. (a) Suggest a mechanism to explain how these two products are formed. (b) Your mechanism for part (a) should be different from the usual mechanism of the reaction of \(\mathrm{SOCl}_{2}\) with alcohols. Explain why the reaction follows a different mechanism in this case. Equation Transcription: Text Transcription: OH SOCI_2 CI CI SOCI_2

Give the structures of the products you would expect when each alcohol reacts with (1) \(\mathrm{HCl}, \mathrm{ZNC} 1_{2}\) (2) \(\mathrm{HBr}\) (3) \(P B r_{3}\) (4) \(P / I 2\) (5) \(\mathrm{SOCI}_{2}\) (a) butan-1-ol (b) 2-methylbutan-2-ol (c) 2,2-dimethylbutan-1-ol (d) cis-3-methylcyclopentanol Equation Transcription: Text Transcription: HCI,ZNC1_2 HBr PBr_3 P/I2 SOCI_2

Problem 22P Predict the products of the sulfuric acid-catalyzed dehydration of the following alcohols. When more than one product is expected, label the major and minor products. (a) 2-methylbutan-2-ol (b) pentan-1-ol (c) pentan-2-ol (d) 1-isopropylcyclohexanol (e) 2-methylcyclohexanol

Contrast the mechanisms of the two preceding reactions, the dehydration and condensation of ethanol.

Explain why the acid-catalyzed condensation is a poor method for the synthesis of an unsymmetrical ether such as ethyl methyl ether, \(\mathrm{CH}_{3} \mathrm{CH}_{2}-0-\mathrm{CH}_{3}\) Equation Transcription: Text Transcription: CH_3CH_2-0-CH_3

Some alcohols undergo rearrangement or other unwanted side reactions when they dehydrate in acid. Alcohols may be dehydrated under mildly basic conditions using phosphorus oxychloride \(\left(\mathrm{POCI}_{3}\right)\) in pyridine. The alcohol reacts with phosphorus oxychloride much like it reacts with tosyl chloride (Section 11-5), displacing a chloride ion from phosphorus to give an alkyl dichlorophosphate ester. The dichlorophosphate group is an outstanding leaving group. Pyridine reacts as a base with the dichlorophosphate ester to give an E2 elimination. Propose a mechanism for the dehydration of cyclohexanol by \(\mathrm{POCI}_{3}\) in pyridine. Equation Transcription: Text Transcription: (POCI_3) POCI_3

When the following substituted cycloheptanol undergoes dehydration, one of the minor products has undergone a ring contraction. Propose a mechanism to show how this ring contraction occurs. Equation Transcription: Text Transcription: H_3C CH_3 CH_3 OH H_2SO_4 H_2O. heat H_3C CH_2 CH_3

Propose a mechanism for each reaction. Equation Transcription: Text Transcription: H_3C HO OH CH_3 H+ OH OH Ph Ph H_2SO_4 Ph Ph

The following reaction involves a starting material with a double bond and a hydroxyl group, yet its mechanism resembles a pinacol rearrangement. Propose a mechanism, and point out the part of your mechanism that resembles a pinacol rearrangement. Equation Transcription: Text Transcription: OH CH=CH_2 H_2SO_4 CH_3

Predict the products formed by periodic acid cleavage of the following diols. Equation Transcription: Text Transcription: CH_3CH(OH)CH(OH)CH_3 CH_2OH OH Ph-C-CH(OH)CH_2CH_3 CH_3

Show the alcohol and the acid chloride that combine to make the following esters. Equation Transcription: Text Transcription: CH_3CH_2CH_2C-OCH_2CH_2CH_3 CH_3(CH_2)_3-O-C-CH_2CH_3 H_3C-O-C-CH(CH_3_)2

Problem 32SP Use resonance forms of the conjugate bases to explain why methanesulfonic acid (CH3SO3H, pKa = -2.6) is a much stronger acid than acetic acid (CH3COOH, pKa = 4.8).

A good Williamson synthesis of ethyl methyl ether would be What is wrong with the following proposed synthesis of ethyl methyl ether? First, ethanol is treated with acid to protonate the hydroxyl group (making it a good leaving group), and then sodium methoxide is added to displace water. Equation Transcription: Text Transcription: CH_3CH_2-O-Na+ + CH_3I CH_3CH_2-O-CH_3 + NaI CH_3CH_2-OH + H+ CH_3CH_2-OH_2 CH_3CH_2-O-CH_3

Problem 34SP (a) Show how ethanol and cyclohexanol may be used to synthesize cyclohexyl ethyl ether (tosylation followed by the Williamson ether synthesis). (b) Why can’t we synthesize this product simply by mixing the two alcohols, adding some sulfuric acid, and heating?

Problem 35SP A student wanted to use the Williamson ether synthesis to make (R)-2-ethoxybutane. He remembered that the Williamson synthesis involves an displacement, which takes place with inversion of configuration. He ordered a bottle of (S)-butan-2-ol for his chiral starting material. He also remembered that the SN2 goes best on primary halides and tosylates, so he madeethyl tosylate and sodium (S)-but-2-oxide. After warming these reagents together, he obtained an excellent yield of 2-ethoxybutane. (a) What enantiomer of 2-ethoxybutane did he obtain? Explain how this enantiomer results from the sN2 reaction of ethyl tosylate with sodium (S)-but-2-oxide. (b) What would have been the best synthesis of (R)-2-ethoxybutane? (c) How can this student convert the rest of his bottle of (S)-butan-2-ol to (R)-2-ethoxybutane?

Problem 36SP The anions of phenols (phenoxide ions) may be used in the Williamson ether synthesis, especially with very reactive alkylating reagents such as dimethyl sulfate. Using phenol, dimethyl sulfate, and other necessary reagents, show how you would synthesize methyl phenyl ether.

Problem 37SP To practice working through the early parts of a multistep synthesis, devise syntheses of (a) pentan-3-one from alcohols containing no more than three carbon atoms. (b) 3-ethylpentan-2-one from compounds containing no more than three carbon atoms.

Problem 39SP Show how you would convert 2-methylcyclopentanol to the following products. Any of these products may be used as the reactant in any subsequent part of this problem. (a) 1-methylcyclopentene (b) 2-methylcyclopentyl tosylate (c) 2-methylcyclopentanone (d) 1-methylcyclopentanol (e) 1,2-dimethylcyclopentanol (f) 1-bromo-2-methylcyclopentane (g) 2-methylcyclopentyl acetate (h) 1-bromo-1-methylcyclopentane

In each case, show how you would synthesize the chloride, bromide, and iodide from the corresponding alcohol. (a) 1-halobutane ( bromo, iodo) (b) halocyclopentane (c) 1-halo-1-methylcyclohexane (d) 1-halo-2-methylcyclohexane

Problem 41SP Predict the major products of the following reactions, including stereochemistry where appropriate. (a) ( R)-butan-2-ol + TsCl in pyridine (b) (S)-2-butyl tosylate + NaBr (c) cyclooctanol + CrO3/H2SO4 (d) cyclopentylmethanol + CrO3 . pyridine. HCl (e) cyclopentylmethanol + Na2Cr2O7/H2SO4 (f) cyclopentanol + HCl/ZnCl2 (g) n-butanol + HBr (h) cyclooctylmethanol + CH3CH2MgBr (i) potassium tert-butoxide + methyl iodide (j) sodium methoxide + tert-butyl iodide (k) cyclopentanol + H2SO4/heat (l) product from (k) + OsO4/H2O2, then HIO4 (m) sodium ethoxide + 1-bromobutane (n) sodium ethoxide + 2-methyl-2-bromobutane (o) octan-1-ol + DMSO + oxalyl chloride (p) 4-cyclopentylhexan-1-ol + DMP reagent

Show how you would accomplish the following synthetic conversions. Equation Transcription: Text Transcription: OH OCH_2CH_3 CH_2Br Br C-CH_2CH_2CH_3 CH_2OH CHCH_2CH_3

Predict the esterification products of the following acid/alcohol pairs. Equation Transcription: Text Transcription: CH_3CH_2CH_2COOH+CH_3OH CH_3OH+HNO_3 2 CH_3CH_2OH+H_3PO_4 COOH + CH_3CH2OH OH + CH_3-C-OH

Problem 43SP Predict the major products of dehydration catalyzed by sulfuric acid. (a) hexan-1-ol (b) hexan-2-ol (c) pentan-3-ol (d) 1-methylcyclopentanol (e) cyclopentylmethanol (f) 2-methylcyclopentanol

Problem 7P A chronic alcoholic requires a much larger dose of ethanol as an antidote to methanol poisoning than does a nonalcoholic patient. Suggest a reason why a larger dose of the competitive inhibitor is required for an alcoholic.

Problem 8P Unlike ethylene glycol, propylene glycol (propane-1,2-diol) is nontoxic because it oxidizes to a common metabolic intermediate. Give the structures of the biological oxidation products of propylene glycol.

Predict the major products of the following reactions. (a) ethyl tosylate + potassium tert-butoxide (b) isobutyl tosylate + \(\mathrm{NaI}\) (c) (R)-2-hexyl tosylate + \(\mathrm{NaCN}\) (d) the tosylate of cyclohexylmethanol + excess \(\mathrm{NH}_{3}\) (e) n-butyl tosylate + sodium acetylide, \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}:^{-}{ }^{+} \mathrm{Na}\) Equation Transcription: Text Transcription: NaI NaCN NH_3 H-C{equiv}C:^{-} ^{+}Na

Compound A is an optically active alcohol. Treatment with chromic acid converts A into a ketone, B. In a separate reaction, A is treated with \(\mathrm{PBr}_{3}\) converting A into compound C. Compound C is purified, and then it is allowed to react with magnesium in ether to give a Grignard reagent, D. Compound B is added to the resulting solution of the Grignard reagent. After hydrolysis of the initial product (E), this solution is found to contain 3,4-dimethylhexan-3-ol. Propose structures for compounds A, B, C, D, and E. Equation Transcription: Text Transcription: PBr_3 PBr_3 Mg Na_{2}Cr_{2}O_{7}, H_{2}SO_4 H_{3}O^+

Give the structures of the intermediates and products V through Z. Equation Transcription: Text Transcription: OH PBr_3 Mg H_{3}O^+ CH_{3}C-Cl Na_{2}Cr_{2}O_7 H_{2}SO_4

Under acid catalysis, tetrahydrofurfuryl alcohol reacts to give surprisingly good yields of dihydropyran. Propose a mecha- nism to explain this useful synthesis. Equation Transcription: Text Transcription: CH_{2}OH H^+

Predict the products you expect when the following starting material undergoes oxidation with an excess of each of the reagents shown below. (a) chromic acid (b) PCC (pyridinium chlorochromate) (c) sodium hypochlorite (d) DMSO and oxalyl chloride (e) DMP (periodinane) reagent Equation Transcription: Text Transcription: HO CH_{3} CH_{2}OH OH

Suggest the most appropriate method for each of the following laboratory syntheses. In each case, suggest both a chromium reagent and a chromium-free reagent. (a) butan-1-ol butanal, \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CHO}\) (b) but-2-en-1-ol but- 2 -enoic acid, \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}-\mathrm{COOH}\) (c) butan-2-ol butan-2-one, \(\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{3}\) (d) cyclopentanol 1-ethylcyclopentanol (two steps) (e) cyclopentylmethanol 1-cyclopentylpropan-1-ol (two steps) (f) 1 -methylcyclohexanol 2-methylcyclohexanone (several steps) Equation Transcription: Text Transcription: CH_{3}CH_{2}CH_{2}CHO CH_{3}CH=CH-COOH CH_{3}COCH_2CH_3

Problem 49SP Predict the major products (including stereochemistry) when cis-3-methylcyclohexanol reacts with the following reagents. (a) PBr 3 (b) SOCl 2 (c) Lucas reagent (d) concentrated HBr (e) TsCl/pyridine, then NaBr

Problem 50SP Show how you would use simple chemical tests to distinguish between the following pairs of compounds. In each case, describe what you would do and what you would observe. (a) butan-1-ol and butan-2-ol (b) butan-2-ol and 2-methylbutan-2-ol (c) cyclohexanol and cyclohexene (d) cyclohexanol and cyclohexanone (e) cyclohexanone and 1-methylcyclohexanol

Write the important resonance forms of the following anions. Equation Transcription: Text Transcription: C=C ^-O-S-CH_3 O^-

Problem 46SP Show how you would convert (S)-hexan-2-ol to (a) (S)-2-chlorohexane (b) (R)-2-bromohexane (c) (R)-hexan-2-ol

When 1-cyclohexylethanol is treated with concentrated aqueous HBr, the major product is 1-bromo-1-ethylcyclohexane. (a) Propose a mechanism for this reaction. (b) How would you convert 1-cyclohexylethanol to (1-bromoethyl)cyclohexane in good yield? Equation Transcription: Text Transcription: OH HBr H_{2}O Br OH Br

Show how you would make each compound, beginning with an alcohol of your choice. Equation Transcription: Text Transcription: CHO CH_{2}Br OCH_3 Cl CH_3 CH_3 CH_3 C-OH CH_3 OTs

Propose mechanisms for the following reactions. In most cases, more products are formed than are shown here. You only need to explain the formation of the products shown, however. Equation Transcription: Text Transcription: CH_{2}-OH HCl, ZnCl_2 Cl H_{3}C OH H_{2}SO_4 CH_3 CH_3 OH OH H_{2}SO_4

Show how you would synthesize the following compounds. As starting materials, you may use any alcohols containing four or fewer carbon atoms, cyclohexanol, and any necessary solvents and inorganic reagents. Equation Transcription: Text Transcription: CH_3 OCH_3 C-CH_3 CH_{2}CH_3 OH OH Br CH_3 N{equiv}C CH_{2}CH_3 CHOCH_{2}CH_3 OH OH

Show how you would synthesize the following compound. As starting materials, you may use any alcohols containing five or fewer carbon atoms and any necessary solvents and inorganic reagents.

The following pseudo-syntheses (guaranteed not to work) exemplify a common conceptual error. (a) What is the conceptual error implicit in these syntheses? (b) Propose syntheses that are more likely to succeed. Equation Transcription: Text Transcription: (CH_{3})_{3}C-Br CH_{3}OH (CH_{3})_{3}C^+ Br^- Na^{+} ^{-}OCH_{3} (CH_{3})_{3}C-OCH_{3} OH H_{2}SO_{4} OH_{2} Na+ -OCH3 OCH3+H2O

Two unknowns, X and Y, both having the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}\), give the following results with four chemical tests. Propose structures for X and Y consistent with this information. Equation Transcription: Text Transcription: C_{4}H_{8}O