orgo alkynes

what are the two types of reductions?

chemical and catalytic

what reaction conditions reduce to a cis alkene?

catalytic reduction with Lindlar’s

H₂, Lindlar’s

what reaction conditions reduce to a trans alkene?

chemical reduction

Na⁰ / NH₃

What reaction conditions reduce to an alkane?

catalytic reduction without Lindlar’s

H2/Pd or H2/Pt or H2/Ni

What are the reaction conditions for hydration?

HgSO_4, H2O/H₂SO₄

What is important to remember about hydration?

it forms an enol that is in equilibrium with a ketone (tautomerization)

What are the two forms of hydroboration?

acidic workup and oxidative workup

what are the reaction conditions for the acidic workup (hydroboration)

AcOH

what are the reaction conditions for the oxidative workup (hydroboration)

NaOH, H₂O₂

what are the reaction conditions for hydroboration of a terminal alkyne

9-BBN or (Sia)₂B and THF/NaOH, H₂O₂

what does the acidic workup of hydroboration result in?

it reduces to a cis alkene like catalytic reduction with lindlar’s catalyst

what does the oxidative workup of hydroboration of an internal alkyne result in?

it results in tautomerization, where the OH will turn into a ketone

what does the oxidative workup of hydroboration of a terminal alkyne result in?

it results in tautomerization which forms an aldehyde

what are the reaction conditions for hydrohalogenation?

H-X

what is the difference between a hydrohalogenation product with one equivalent and with two equivalents?

with one equivalent: there will be a halogen on the more substitued side of the alkene

with two: it is reduced to an alkane with two halogens on the more substituted side of the alkane.

what are the reaction conditions for halogenation?

X₂, H₂O

what is the difference between a halogenation product with one equivalent and with two equivalents?

with one: one halogen on each side of the alkene

with two: reduces to an alkane with two halogens on each side of the alkane.

What are the reaction conditions for the preparation of internal alkynes?

first, an alkene must undergo halogenation. then, the halogenation product will react in NaNH₂/NH₃

What are the reaction conditions for the preparation of terminal alkynes?

first, an alkene must undergo halogenation. then, the halogenation product will react in NaNH₂/NH_3. They then need a third equivalent of base to deprotonate the terminal alkyne. Then, they react with water to form the final terminal alkyne.