Quiz - Alkynes | Alkynes

1

The triple bond of an alkyne is made up of:

3 σ bonds

2 σ bonds + 1 π bond

1 σ bond + 2 π bonds

3 π bonds

C ≡ C bond of alkynes:
​​​​​​​1 σ bond ⇒ formed from 2 sp orbitals of carbon atoms
2 π bonds ⇒ formed from 4 p orbitals of carbon atoms

2

How many distinct alkynes are there with a molecular formula of C4H6?

0

1

2

3

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3

Which of the following reagents should be used to convert but-2-yne to (E)-but-2-ene?

H2, Pt

H2, Lindlar catalyst

Na, NH3 (liq.)

HgSO4, H2O

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4

Which of the following reagents should be used to convert but-2-yne to (Z)-but-2-ene?

H2, Pt

H2, Lindlar catalyst

Na, NH3 (liq.)

HgSO4, H2O

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5

Which of the species below is less basic than acetylide?

n​​​​​​​BuLi

MeMgBr

MeONa

All of the above

n​​​​​​​BuLi (pKa ~ 50) = MeMgBr (pKa ~ 50) > Alkynes (pKa = 25) > MeONa (pKa = 15-16)

6

Which of the alkyne addition reactions below involves an enol intermediate?

Addition of hydrogen halide

Hydroboration - Oxidation

Hydration with HgSO4

None of the above

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