3. Alkynes Flashcards
how can alkynes be produced or prepared - what are the reactants involved and catalysts
didehydrohalogenation of dihaloalkanes
via KOH or NaOH (ethanol)
produces alkene and then alkyne
what are the 4 types of reactions alkynes can undergo
hydrogenation
electrophillic addition of HX and X2
hydration
Formation of alkynide anions from terminal alkynes
what are the bonds involved in the triple bond of a alkyne
1 x sigma
2 x pi
what is the hybridization of the triple bond of alkynes
sp hybrid
what is the source of e- in an alkyne reaction and what is the nucleophile
the triple bond is the source of e- and acts as a nucleophile
what are the reactants involved when an alkyne produces an alkane
Pt/Pd catalyst
2 moles of H2
what orientation or stereochemistry does the alkane produced from hydrogenation reaction of alkyne have
both H are added in syn
what does alkyne reaction with H2 and Pt/Pd catalyst produce
alkane
what are the reactants involved when an alkyne produces an E alkene
lithium/liquid NH3
followed by H2O
what orientation or stereochemistry does the alkane produced from hydrogenation reaction of alkyne producing an E alkene have
H are added in trans
what does alkyne reaction with 1.lithium/liquid NH3
2. H2O
produce
E alkene
what are the reactants involved when an alkyne produces a Z alkene
[PdPb(OAc)2]/H2
lindlar catalyst
what orientation or stereochemistry does the alkane produced from hydrogenation reaction of alkyne producing Z alkene have
H added in syn
what rule does electrophillic addition of HX and H2 with alkyne follow
markovnikoff rule
what happens when you add one equivalent of reagent HX or X2 to an alkyne
haloalkene
what happens when you add 2 equivalents of reagent HX or X2 to an alkyne (in excess)
dihaloalkane
what stereochemistry will the resulting haloalkene or dihaloalkane have from the electrophillic addition reaction of HX or X2 with alkyne
anti stereochemistry
what are the reactants involved when an alkyne produces a ketone
1 mole equivalent of H2O with H2SO4(aq) and HqSO4
what is produced when you add 1 mole equivalent of H2O with H2SO4(aq) and HqSO4 to an alkyne
produces ketones
when an alkyne has undergone hydration reaction to form a ketone what equilibrium does it exist in - what does this mean
tautomeric equilibrium
internal reorganization
what reagents and reactants are needed to produce alkynide anions from terminal alkynes
strong base = Na+NH2- or NaH
what kind of alkyne can produce an alkynide anions
terminal alunes
what is the structure of an alkynide anion
RC(triple bond)C-
what is produced with an alkyne reacts with a strong base such as Na+NH2- or NaH
forms alkynide anions
