Question 1

Select the best explanation for why methanol, CH3OH, cannot be used as a solvent for the deprotonation of a terminal alkyne by sodium amide, NaNH2.

Accepted Answer

A)   Sodium amide is not a strong enough base to deprotonate the alkyne.
B)   Sodium amide in methanol reduces alkynes to alkenes.
C)   Methanol is a poor solvent for dissolving alkynes.
D)   Methanol is more acidic than the alkyne and will be deprotonated instead.
E)   Methanol is toxic, and should be avoided when possible.F) None of the above
G) A) and E)

Question 2

Which statement below best explains why the Ka of acetylene is greater than that of ethylene?

Accepted Answer

A)   Acetylide anions are resonance stabilized.
B)   The 4   π\piπ electrons of the acetylide anion better stabilize a negative charge.
C)   The electronegativity of sp carbons is greater than that of sp2 carbons.
D)   The electronegativity of sp carbons is less than that of sp2 carbons.
E)   Acetylene has only two hydrogen atoms while ethylene has four. F) A) and C)
G) A) and B)

Question 3

Draw all of the constitutionally isomeric alkynes with molecular formula C5H8.

Accepted Answer

Question 4

For the reaction below, which of the alkynes listed would be expected to produce the product under the conditions shown?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   VF) None of the above
G) A) and B)

Question 5

Which of the following is a structure for octa-3,6-dien-1-yne?

Accepted Answer

A)   HC≡CCH=CHCH=CHCH2CH3
B)   CH3CH=CHCH2C≡CC≡CH
C)   CH3CH=CHCH2CH=CHC≡CH
D)   CH3C≡CCH=CHCH=CHCH3
E)   H2C=CHC≡CCH2CH=CHCH3F) B) and E)
G) C) and E)

Question 6

The expected major product from treatment of 1-pentyne with excess HBr is:

Accepted Answer

A)   1,1-dibromo-1-pentene
B)   1,2-dibromo-1-pentene
C)   1,1-dibromopentane
D)   2,2-dibromopentane
E)   1,1,2,2-tetrabromopentaneF) A) and B)
G) A) and D)

Question 7

Of the reaction conditions provided below, which would be expected to convert 1 mole of 4-methyl-1-pentyne into 2-methylpentane?

Accepted Answer

A)   H2, Lindlar's catalyst
B)   Na, NH3(l) 
C)   2 moles of HCl
D)   2 moles H2, Pt
E)   1 mole H2, PtF) C) and E)
G) A) and B)

Question 8

For the reaction shown, which of the compounds listed would be the expected major, and final, organic product?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   VF) B) and E)
G) A) and D)

Question 9

For the transformation shown, select the most appropriate reagent(s)  to effect the change. 2SO4, HgSO4, H2O B)  1. Disiamylborane, 2. HO-, H2O2 C)  K2Cr2O7, H+ D)  NaOCl E)  H2, Pd" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   H2SO4, HgSO4, H2O
B)   1. Disiamylborane, 2. HO-, H2O2
C)   K2Cr2O7, H+
D)   NaOCl
E)   H2, PdF) A) and E)
G) A) and D)

Question 10

What is the IUPAC name for the molecule shown below?

Accepted Answer

A)   1,1,1-trichloro-4-hexyne
B)   4,4,4-trichloro-1-butyne
C)   1,1,1-trichloro-2-butyne
D)   5,5,5-trichloro-2-pentyne
E)   6,6,6-trichloro-2-hexyneF) B) and D)
G) C) and D)

Question 11

When preparing terminal alkynes by an elimination reaction, sodium amide (NaNH2)  dissolved in liquid ammonia (NH3)  is used most frequently. Which of the following statements offers the best explanation for the above statement?

Accepted Answer

A)   The above statement is false; terminal alkynes are not produced under the given conditions.
B)   Sodium amide deprotonates the terminal alkyne, driving formation of the alkynide ion.
C)   Only sodium amide is a strong enough base to deprotonate a carbon.
D)   Terminal alkynes are more stable than the internal alkynes, and are always the favored product.
E)   Steric hindrance favors preparation of the less substituted terminal alkyne.F) C) and E)
G) A) and D)

Question 12

What is the IUPAC name for the molecule shown below?

Accepted Answer

A)   3-bromo-4-acetylenylheptane
B)   3-(1-bromopropyl) -1-hexyne
C)   3-bromo-4-propyl-5-hexyne
D)   4-bromo-3-propyl-1-hexyne
E)   4-ethynyl-5-bromo-heptaneF) A) and B)
G) A) and D)

Question 13

Provide the IUPAC name for CH3CHBrC≡C(CH2)3CH3.

Accepted Answer

2-bromo-3-...

Question 14

Provide the structure(s) of the expected major organic product(s) from the following reaction:

Accepted Answer

The answer of Provide the structure(s) of the expected major...

Question 15

Draw the line-bond structure for the compound with the IUPAC name 2,5,9-trimethyl-2-decen-7-yne.

Accepted Answer

The answer of Draw the line-bond structure for the compound...

Question 16

For the reaction below, how many different organic products would be expected?

Accepted Answer

A)   one
B)   two
C)   three
D)   four
E)   fiveF) A) and B)
G) D) and E)

Question 17

Reaction of (3E,5Z) -3-methylhepta-3,5-dien-1-yne with H2 and Pd/C will produce which of the compounds below?

Accepted Answer

A)   1-sec-butylbutane
B)   2-butylbutane2
C)   3-methylheptane
D)   3-methyl-1-heptyne
E)   (3E,5Z) -3-methyl-1,3,5-heptatrieneF) A) and B)
G) A) and C)

Question 18

Which of the alkyl bromides listed would work as a reagent in step 2 of the reaction sequence shown, with the resulting major product being an internal alkyne?

Accepted Answer

A)   I and III
B)   II and IV
C)   III, IV, V
D)   I, II, IV
E)   II, III, VF) B) and E)
G) B) and D)

Question 19

Select the reagent(s)  expected to accomplish the transformation shown below. 2, Ni B)  H2, Ni2B C)  Na, NH3(l)  D)  A or B E)  B or C" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   H2, Ni
B)   H2, Ni2B
C)   Na, NH3(l) 
D)   A or B
E)   B or CF) A) and D)
G) B) and D)

Question 20

Ozonolysis of one mole of the compound shown is expected to produce how many moles of CO2 upon completion of the reaction? 2 upon completion of the reaction?   A)  1 B)  2 C)  3 D)  4 E)  8" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   8F) A) and E)
G) A) and C)

Exam 10: Alkynes

Which statement below best explains why the Ka of acetylene is greater than that of ethylene?

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Select the best explanation for why methanol, CH3OH, cannot be used as a solvent for the deprotonation of a terminal alkyne by sodium amide, NaNH2.

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Which of the following is a structure for octa-3,6-dien-1-yne?

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For the transformation shown, select the most appropriate reagent(s) to effect the change.

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Select the reagent(s) expected to accomplish the transformation shown below.

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Draw all of the constitutionally isomeric alkynes with molecular formula C5H8.

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For the reaction shown, which of the compounds listed would be the expected major, and final, organic product?

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For the reaction below, which of the alkynes listed would be expected to produce the product under the conditions shown?

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For the reaction below, how many different organic products would be expected?

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Draw the line-bond structure for the compound with the IUPAC name 2,5,9-trimethyl-2-decen-7-yne.

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What is the IUPAC name for the molecule shown below?

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Ozonolysis of one mole of the compound shown is expected to produce how many moles of CO2 upon completion of the reaction?

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Provide the IUPAC name for CH3CHBrC≡C(CH2)3CH3.

Correct Answerverified2-bromo-3-...View AnswerShow Answer

The expected major product from treatment of 1-pentyne with excess HBr is:

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Which of the alkyl bromides listed would work as a reagent in step 2 of the reaction sequence shown, with the resulting major product being an internal alkyne?

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When preparing terminal alkynes by an elimination reaction, sodium amide (NaNH2) dissolved in liquid ammonia (NH3) is used most frequently. Which of the following statements offers the best explanation for the above statement?

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Reaction of (3E,5Z) -3-methylhepta-3,5-dien-1-yne with H2 and Pd/C will produce which of the compounds below?

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Of the reaction conditions provided below, which would be expected to convert 1 mole of 4-methyl-1-pentyne into 2-methylpentane?

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Provide the structure(s) of the expected major organic product(s) from the following reaction:

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What is the IUPAC name for the molecule shown below?

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Which statement below best explains why the K_a of acetylene is greater than that of ethylene?

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Select the best explanation for why methanol, CH₃OH, cannot be used as a solvent for the deprotonation of a terminal alkyne by sodium amide, NaNH₂.

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Draw all of the constitutionally isomeric alkynes with molecular formula C₅H₈.

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Ozonolysis of one mole of the compound shown is expected to produce how many moles of CO₂ upon completion of the reaction?

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Provide the IUPAC name for CH₃CHBrC≡C(CH₂)₃CH₃.

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2-bromo-3-...
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When preparing terminal alkynes by an elimination reaction, sodium amide (NaNH₂) dissolved in liquid ammonia (NH₃) is used most frequently. Which of the following statements offers the best explanation for the above statement?

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Reaction of (3E,5Z) -3-methylhepta-3,5-dien-1-yne with H₂and Pd/C will produce which of the compounds below?

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