Ch. 11 - Alkyne Chemistry (Week 4) Flashcards
What is the hybridization of carbons in alkynes?
sp
Is sodium amide a good nuc or base?
VERY strong base (nitrogen not super EN so wants to give up e-), but not good nuc (doesn’t do Sn2)
What are three ways alkynes are made?
from vicinal or geminal dihalides via E2x2
from alkyl halides and lithium acetylide via Sn2
What dictates if a product is major in alkyne addition reactions?
sterics
How many products does a symmetrical internal alkyne give in hydrohalogenation?
one prod (doesnt matter which carbon halides go on)
How many products does a unsymmetrical internal alkyne give in hydrohalogenation?
two products, 1:1 ratio
How many products does a terminal alkyne give in hydrohalogenation?
one product that is regioselective via markovnikov’s rule
Does hydrohalogenation form carbocations?
yes
Is halogenation of alkynes (X2) anti or syn addition?
exclusively anti, becuase a bridged halonium ion forms
Does halogenation of a symmetric alkyne (X2) give chiral or achiral product?
achiral product, even though there is a chiral intermediate
Do carbocations form for halogenation of alkynes (X2) have carbocations?
No
How many products does a symmetrical and internal alkyne give by acidic hydration?
one
How many products does an unsymmetrical and internal alkyne give by acidic hydration?
two, 1:1 mixture
How many products does a terminal alkyne give by acidic hydration?
one
