Alcohols and Phenols

Reduction of 2-butanone with NaBH₄ yields 2-butanol. Is the product chiral? Is it optically active? Explain.

The conversion of 3° alcohols into 3° alkyl halides under acidic conditions involves two cationic intermediates. For each reaction, draw the complete mechanism using curved arrows.

Identify the type of substitution  ${\mathbf{SN}}_{\mathbf{1}}\mathbf{,}{\mathbf{SN}}_{\mathbf{2}}$mechanism involved in the conversion of the alcohol shown into the corresponding alkyl halide.

(a)

(b)

(c)

Question:Identify the type of substitution mechanism ${\mathbf{SN}}_{\mathbf{1}}$,${\mathbf{SN}}_{\mathbf{2}}$ involved in the conversion of the alcohol shown into the corresponding alkyl halide.

a. 

b) 

c) 

The conversion of 3° alcohols into alkenes under acidic conditions involves two cationic intermediates. For each reaction, draw the complete mechanism using curved arrows.

(a)

(b)

(c)

Question: The conversion of 3° alcohols into alkenes under acidic conditions involves two cationic intermediates. For each reaction, draw the complete mechanism using curved arrows.

a) 

b) 

c) 

For each reaction, write the mechanism using curved arrows for the conversion of the alcohol into the corresponding alkene with POCl₃. In each case, explain the regiochemistry of the elimination.

(a)

(b)

(c)

Question:For each reaction, write the mechanism using curved arrows for the conversion of the alcohol into the corresponding alkene with POCl₃. In each case, explain the regiochemistry of the elimination.

a) 

b)

c) 

The trimethylsilyl (TMS) protecting group is one of several silicon protecting groups for alcohols. For each reaction, draw the mechanism for the protection of (R)-3-bromo-1-butanol with the following silyl chlorides, using triethylamine as the base: 

(a) tert-butyldimethylsilyl chloride (TBS-Cl) 

(b) triisopropylsilyl chloride (TIPS-Cl) 

 (c) triethylsilyl chloride (TES-Cl)

Question:The trimethylsilyl (TMS) protecting group is one of several silicon protecting groups for alcohols. For each reaction, draw the mechanism for the protection of (R)-3-bromo-1-butanol with the following silyl chlorides, using triethylamine as the base: 

(a) tert-butyldimethylsilyl chloride (TBS-Cl) 

(b) triisopropylsilyl chloride (TIPS-Cl) 

(c) triethylsilyl chloride (TES-Cl)

Question: When the alcohol below is treated with ${\mathbf{POCl}}_{\mathbf{3}}$and pyridine, the expected elimination product is formed. However, when the same alcohol is treated with ${\mathbf{H}}_{\mathbf{2}}{\mathbf{SO}}_{\mathbf{4}}$, the elimination product is 1,2-dimethylcyclopentene. Propose a mechanism for each pathway to account for these differences.

Question:When the alcohol below is treated with ${\mathbf{POCI}}_{\mathbf{3}}$and pyridine, the expected elimination product is formed. However, when the same alcohol is treated with ${\mathbf{H}}_{\mathbf{2}}{\mathbf{SO}}_{\mathbf{4}}$, the elimination product is 1,2-dimethylcyclopentene. Propose a mechanism for each pathway to account for these differences.

Phenols generally have lower pKa’s than aliphatic alcohols because of resonance stabilization with the aromatic ring. Draw all of the resonance contributors for the phenolate ions below. Make note of how the substituents either stabilize or destabilize the system.

Question: Phenols generally have lower pKa’s than aliphatic alcohols because of resonance stabilization with the aromatic ring. Draw all of the resonance contributors for the phenolate ions below. Make note of how the substituents either stabilize or destabilize the system.

Question: Give IUPAC names for the following compounds:

Question: Give IUPAC names for the following compounds:

Draw and name the eight isomeric alcohols with the formula C₅H₁₂O

Question:Which of the eight alcohols that you identified in Problem 17-38 react with ${\mathbf{CrO}}_{\mathbf{3}}$ in aqueous acid? Show the products you would expect from each reaction

Named bombykol, the sex pheromone secreted by the female silkworm

moth has the formula C₁₆H₂₈O and the systematic name (10E,12Z)-

10,12-hexadecadien-1-ol. Draw bombykol, showing the correct geometry

for the two double bonds.

Carvacrol is a naturally occurring substance isolated from oregano,

thyme, and marjoram. What is its IUPAC name?

What Grignard reagent and what carbonyl compound might you start with to prepare the following alcohols?

(a)

(b)

(c)

(d)

(e)

(f)

What carbonyl compounds would you reduce to prepare the followingalcohols? List all possibilities.

(a)

(b)

(c)

What carbonyl compounds might you start with to prepare the following compounds by Grignard reaction? List all possibilities.

(a) 2-Methyl-2-propanol

 (b) 1-Ethylcyclohexanol

(c) 3-Phenyl-3-pentanol 

(d) 2-Phenyl-2-pentanol

(e)

(f)

How would you synthesize the following alcohols, starting with benzene and other alcohols of six or fewer carbons as your only organic reagents?

(a) 

(b) 

(c) 

(d) 

What products would you obtain from reaction of 1-pentanol with the following reagents?

(a) ${\mathbf{PBr}}_{\mathbf{3}}$

(b) ${\mathbf{SOCl}}_{\mathbf{2}}$

(c) ${\mathbf{CrO}}_{\mathbf{3}}\mathbf{ }\mathbf{,}\mathbf{ }{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{ }\mathbf{,}\mathbf{ }{\mathbf{H}}_{\mathbf{2}}{\mathbf{SO}}_{\mathbf{4}}$

(d) Dess- Martin periodinane

How would you prepare the following compounds from 1-phenylethanol?

More than one step may be required.

(a) Acetophenone 

(b) Benzyl alcohol

(c) m-Bromobenzoic acid 

(d) 2-Phenyl-2-propanol

How would you prepare the following substances from cyclopentanol?

More than one step may be required.

(a) Cyclopentanone 

(b) Cyclopentene

(c) 1-Methylcyclopentanol 

(d) trans-2-Methylcyclopentanol

What products would you expect to obtain from reaction of 1-methylcyclohexanol with the following reagents?

(a) HBr (b) NaH (c) H₂SO₄  (d) Na₂Cr₂O₇

The following ¹H NMR spectrum is that of an alcohol, C₈H₁₀O

. Propose a structure.

Propose structures for alcohols that have the following ${}^{\mathbf{1}}\mathit{H}$  NMR spectra:

(a) ${\mathbf{C}}_{\mathbf{5}}{\mathbf{H}}_{\mathbf{12}}\mathbf{O}$

(b) ${\mathbf{C}}_{\mathbf{8}}{\mathbf{H}}_{\mathbf{10}}\mathbf{O}$

Propose a structure consistent with the following spectral data for a

compound ${\mathbf{C}}_{\mathbf{8}}{\mathbf{H}}_{\mathbf{18}}{\mathbf{O}}_{\mathbf{2}}$  :

IR:  $\mathbf{3350}{\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$

${}^{\mathbf{1}}\mathbf{H}$ NMR: $\mathbf{1}\mathbf{.}\mathbf{56}\mathbf{\delta }$ (12 H, singlet); $\mathbf{1}\mathbf{.}\mathbf{56}\mathbf{\delta }$ (4 H, singlet); $\mathbf{1}\mathbf{.}\mathbf{95}\mathbf{\delta }$ (2 H, singlet)

The NMR spectrum shown is that of 3-methyl-3-buten-1-ol. Assign

all the observed resonance peaks to specific protons, and account for

the splitting patterns.

A compound of unknown structure gave the following spectroscopic data:

Mass spectrum: ${\mathbf{M}}^{+}\mathbf{=}\mathbf{88}\mathbf{.}\mathbf{1}$

IR:  $\mathbf{3600}{\mathbf{cm}}^{-1}$

 ${}^1\mathbf{H}$NMR: 1.4$\mathbf{\delta }$  (2H, quartet, J=7Hz); 1.2$\mathbf{\delta }$ (6H, singlet); 1.0$\mathbf{\delta }$ (1H, singlet); 0.9$\mathbf{\delta }$ (3H, triplet, J=7Hz)

 ${{}^1}^3\mathbf{C}$NMR: 74, 35, 27, 25$\mathbf{\delta }$

(a) Assuming that the compound contains C and H but may or may not contain O, give three possible molecular formulas.

(b) How many protons (H) does the compound contain? 

(c) What functional group(s) does the compound contain?

(d) How many carbons does the compound contain?

(e) What is the molecular formula of the compound? 

(f) What is the structure of the compound?

(g) Assign peaks in the molecule’s NMR spectrum corresponding to specific protons.

Starting from testosterone (Problem 17-62), how would you prepare the following substances?

a.

b.

c.

d.

Compound A, ${\mathbf{C}}_{10}{\mathbf{H}}_{18}\mathbf{O}$ , undergoes reaction with dilute ${\mathbf{H}}_2{\mathbf{SO}}_4$ at $\mathbf{25}\mathbf{°}\mathbf{C}$ to yield a mixture of two alkenes, ${\mathbf{C}}_{10}{\mathbf{H}}_{16}$ . The major alkene product, B, gives only cyclopentanone after ozone treatment followed by reduction with zinc in acetic acid. Write the reactions involved, and identify A and B.

Compound A, ${\mathbf{C}}_5{\mathbf{H}}_{10}\mathbf{O}$, is one of the basic building blocks of nature. All steriods and many other naturally occurring compounds are built from compound A. Spectroscopic analysis of A yields the following information:

IR : $\mathbf{3400}{\mathbf{cm}}^{-1}$; $\mathbf{1640}{\mathbf{cm}}^{-1}$

${}^1\mathbf{H}\mathbf{NMR}$: 1.63$\mathbf{\delta }$ (3H, singlet); 1.70 $\mathbf{\delta }$ (3H, singlet); 3.83 $\mathbf{\delta }$ (1H, broad singlet); 4.15 $\mathbf{\delta }$ (2H, doublet, J=7 Hz); 5.70$\mathbf{\delta }$ (1H, triplet, J = 7 Hz)

1. How many double bonds and/or rings does A have?
2. From the IR spectrum, what is the identity of the oxygen-containing functional group?
3. What kinds of protons are responsible for the NMR absorptions listed?
4. Propose a structure for A.