Section 16.6

With regard to the ¹H NMR spectrum of the molecule shown on the right:

(1) The protons labeled 2 are _________ relative to protons 1.

             A. downfield

B. upfield

C. quartet

D. triplet

E. equivalent

(2) The protons labeled 3 are _________ relative to protons 5.

             A. downfield

B. upfield

C. quartet

D. triplet

E. equivalent

(3) The NMR signal from protons labeled 2 are split into a ________.

             A. downfield

B. upfield

C. quartet

D. triplet

E. equivalent

(4) The NMR signal from protons labeled 1 are split into a ________.

             A. downfield

B. upfield

C. quartet

D. triplet

E. equivalent

(5) A less shielded proton falls ________ on an NMR spectrum in relation to a more shielded proton.

             A. downfield

B. upfield

C. quartet

D. triplet

E. equivalent

(6) A compound of the formula C₅H₁₀O gave the following spectral information:
¹H NMR Spectrum: 6 H doublet @ d1.10; 3 H singlet @ d 2.10; 1 H septet @ d 2.50
IR Spectrum: strong peak at 1720 cm^-1

Which of the following is a reasonable structure for the compound?

             A.

B.

C.

D.

E.

(7) The 1,2 monoaddition product(s) for HCl reacting with 2,4-hexadiene is(are)

             A. No reaction.

B. 5-chloro-2-hexene

C. 4-chloro-2-hexene

D. 2-chloro-3-hexene

E. more than one of the above

(Use the following information for questions 5 — 8.)

1H NMR: 3 H s @ 1.96 d; 2 H s @ 5.00 d; 5 H s @ 7.22 d.

Molecular Formula: C₉H₁₀O₂

UV-Visible: Intense peak at 255 nm
IR Data: 3400 cm^-1, no significant peak; 3100 cm^-1, sharp, medium band; 2900, sharp, medium band; 2250 cm^-1, no significant peak; 1735 cm^-1 strong band; 1610 cm^-1, sharp medium band; 1495, sharp, medium band.

(8) Which of the following is ruled out by the IR information?

             A. carboxylic acid

B. ketone

C. ester

D. aldehyde

E. aromatic systems

(9) The NMR peak at 7.22d is indicative of the presence of a(n)

             A. carboxylic acid.

B. extended conjugated system.

C. ester.

D. acid anhydride.

E. aromatic system.

(10) The fact that all of the peaks in the NMR are singlets means that

             A. a decoupling signal has been added to the spectrum to reduce clutter.

B. the three sets of hydrogens are interchangeable with one another on the NMR timescale.

C. equivalent protons on adjacent carbons do not spilt one another.

D. the three sets of hydrogens are isolated from one another.

E. no information can be gained.

(11) Which of the following is the best structure given the information above?

             A.

B.

C.

D.

E.

(12) Which of the following is (are) true?

I. Pyrrole is aromatic.



IV. Pyridine is aromatic.

II. Pyrrole is basic.

V. Pyridine is basic.

III. Pyrrole is neutral.

VI. Pyridine is neutral.

             A. I and IV only
B. II and V only
C. I and II, IV and V

D. I and III, IV and VI
E. I and III, IV and V

(13) Which of the following ions are aromatic?

             A. I and II only

B. II and III only

C. III only

D. I and III only

E. all of the above

(14) Which of the following are characteristics of aromatic systems in general?
I. Planar structure.
II. Neutral.
III. Carbons only in aromatic substructure.
IV. Unhybridized p-orbitals on each aromatic system atom.

             A. I and II

B. I, II and III

C. I and IV

D. II and III

E. II, III, IV

(15) What is the product formed when 1,2-diethylbenzene is treated with an aqueous solution of KMnO₄?

             A. Naphthalene

B. o-benzenedicarboxylic acid

C. No reaction occurs as the ring is inert.

D. Benzoic acid

E. Benzodiquinone

(16) The non-aromatic reactant in electrophilic substitution reactions involving aromatic systems MUST be

             A. positively charged

B. A Lewis Acid

C. A Nucleophile

D. negatively charged

E. A Lewis Base

(17) What is(are) the product(s) of the reaction of nitrobenzene with Cl₂ in the presence of FeCl₃?

             A. p-chloronitrobenzene

B. o-chloronitrobenzene

C. m-chloronitrobenzene

D. a and c

E. a and b

(18) Which of the following statements is(are) true about electrophilic aromatic substitution to nitrobenzene?
I. Resonance stabilization acts to orient the new electrophile in the ortho position relative to the nitro group.
II. Resonance stabilization acts to orient the new electrophile in the meta position relative to the nitro group.
III. Resonance stabilization acts to orient the new electrophile in the para position relative to the nitro group.

             A. I

B. II

C. III

D. I and III

E. none

(19) Benzene is reacted with chlorobenzene in the presence of AlCl₃. The product is

             A. dibenzene

B. naphthalene

C. anthacene

D. graphite

E. no reaction.

(20) Rank the following from "most reactive" to "least reactive" with respect to electrophilic aromatic substitution.
I. benzene; II. phenol; III. benzonitrile

             A. I > II > III

B. II > I > III

C. I > III > II

D. III > II > I

E. II > III > I

(21) A chemist would choose to use NaBH₄ (in ether) instead of LiAlH₄ (in ether) for reductions in organic reactions because

             A. LiAlH₄ is stable in ether, whereas NaBH₄ is not.

B. NaBH₄ is stable in ether, whereas LiAlH₄ is not.

C. LiAlH₄ is a stronger reducing agent than NaBH₄.

D. LiAlH₄ is unstable and potentially explosive if mishandled.

(22) The molecule p-cyanophenol is a much stronger acid than phenol. Which of the following best explains this observation?

             A. aromatic stabilization of benzylic carbocations

B. hydrogen transfer of an aromatic proton

C. aromatic stabilization of benzylic carbanions

D. resonance stabilization of the resulting cation

E. resonance stabilization of the resulting anion

(23) Alcohols have boiling points elevated from other molecules of similar size. Which of the following best explains this observation?

             A. van der Waals or dispersive interactions

B. strong dipole/dipole interactions

C. extensive hydrogen-bonding

D. ordered packing of molecules

E. most small alcohols are infinitely soluble in water

(Use the following for questions 24 and 25.) The following product was prepared using the Williamson ether synthesis.

(24) The reaction would proceed most readily to the correct product under which the following combinations of reagents / conditions ?

             A. CH₃I + (CH₃)₂CHOH / PCC in CH₂Cl₂

B. CH₃I / NaBH₄ in (CH₃)₂CHOH

C. CH₃OH / 1) Na; 2) (CH₃)₂CHI in ether

D. (CH₃)₂CHOH / 1) Na; 2) CH₃I in ether

(25) The reaction occurs by

             A. S_N2

B. S_N1

C. E2

D. E1

E. radical

		A.	I and IV only
		B.	II and V only
		C.	I and II, IV and V
		D.	I and III, IV and VI
		E.	I and III, IV and V

		A.	I and II only
		B.	II and III only
		C.	III only
		D.	I and III only
		E.	all of the above

		A.	I and II
		B.	I, II and III
		C.	I and IV
		D.	II and III
		E.	II, III, IV

		A.	Naphthalene
		B.	o-benzenedicarboxylic acid
		C.	No reaction occurs as the ring is inert.
		D.	Benzoic acid
		E.	Benzodiquinone

		A.	positively charged
		B.	A Lewis Acid
		C.	A Nucleophile
		D.	negatively charged
		E.	A Lewis Base

		A.	p-chloronitrobenzene
		B.	o-chloronitrobenzene
		C.	m-chloronitrobenzene
		D.	a and c
		E.	a and b

		A.	I > II > III
		B.	II > I > III
		C.	I > III > II
		D.	III > II > I
		E.	II > III > I

		A.	LiAlH₄ is stable in ether, whereas NaBH₄ is not.
		B.	NaBH₄ is stable in ether, whereas LiAlH₄ is not.
		C.	LiAlH₄ is a stronger reducing agent than NaBH₄.
		D.	LiAlH₄ is unstable and potentially explosive if mishandled.

		A.	aromatic stabilization of benzylic carbocations
		B.	hydrogen transfer of an aromatic proton
		C.	aromatic stabilization of benzylic carbanions
		D.	resonance stabilization of the resulting cation
		E.	resonance stabilization of the resulting anion

		A.	van der Waals or dispersive interactions
		B.	strong dipole/dipole interactions
		C.	extensive hydrogen-bonding
		D.	ordered packing of molecules
		E.	most small alcohols are infinitely soluble in water

		A.	CH₃I + (CH₃)₂CHOH / PCC in CH₂Cl₂
		B.	CH₃I / NaBH₄ in (CH₃)₂CHOH
		C.	CH₃OH / 1) Na; 2) (CH₃)₂CHI in ether
		D.	(CH₃)₂CHOH / 1) Na; 2) CH₃I in ether