Chemistry 3719 Chapter 9

What is the approximate pKa of a terminal alkyne?

Approximately 26
What shape does an alkyne adopt about the triple bond?

Linear (since, from VSEPR, only two valences repel)
Which base will completely deprotonate a terminal alkyne, NaOH or NaNH₂?

NaNH₂. Its conjugate acid has a pKa of 36 so NaNH₂ is a very powerful base that is capable of completely deprotonating the alkyne (pKa ~26).
What process is involved when an enol converts to a ketone, or vice versa?

Keto-enol tautomerism
What mechanism is involved when the sodium salt of an alkyne attacks methyl bromide to give the methylated alkyne?

S_N2 reaction
Why is cyclohexyne an impossible molecule to make?

The angles around the alkyne would deviate far too much from the ideal 180^o and subsequently the cycle would be far too strained for the molecule to exist
Are low molecular weight alkynes or low molecular weight alcohols typically more likely to dissolve in water? What is the reasoning behind your answer?

Low molecular weight alcohols since they are more polar and also capable of hydrogen bonding with water
What is the hybridization pattern of C atoms in triple bonds?

sp hybridized
What products are formed when acetylene is combusted in oxygen?

CO₂ and H₂O
Why are alkyne protons more acidic than alkane protons?

The sp-hybridized C atoms in alkynes are more electronegative than sp³ atoms in alkynes; this stabilizes the conjugate base in the alkyne case

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pnorris

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Card Set

Chemistry 3719 Chapter 9

Description

YSU Organic Chemistry

Updated

2011-08-26T19:26:42Z

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