exam 4 orgo alkynes

NBS/hv

allyic bornation

NaNH2 (alone or w H3O+)

forms alkyne

KOH

forms alkyne

HgSO4,H2SO4,H2O

makes keto and enol keto more favored

terminal BH3/THF,H202

makes enol then aldehyde

Terminal Alkyne, H2O,H2SO4,HGSO4

methyl-KETONE

Symmetrical internal alkyne H2O,H2SO4,HGSO4

single ketone

asymmetrical internal alkyne

mixture of ketones

terminal alkyne Sia2BH, 9-BBN, h2o2,oh

aldhyde

Sia2BH, 9BBN, h2o2,oh

ketone

INTERNAL ALKENE 1.BH3/THF 2.H202 H20 NAOH

ketone

H3O+/HGSO4

Makes MIX of inverted methyl ketones

H3O+/HgSO4 Terminal alkyne

methyl ketone

LI/NH3

MAKES TRANS ALKENE

KMNO4, O3

OXIDATIVE CLEAVAGE

NANH2,NH3 + X-Br

adds x-br to chain, in thf adds extra carbon

x2

adds E if eq

HBR

adds z

x2 + UV

one x replaces a H on most subed carbon

HX + ALCHOL

replaces X w OH

PBr3 + SOCl2 + alchol 1* or 2*

Pbr replaces oh 1* w br, socl 1* replaces oh w cl

E2

uses nuc to kick b C proton adjacent to LG out and kick out LG, forming a double bond- concerted

E1

LG leaves, CC forms, shifts take place, db is formed towards most subbed C

Sn2

NUC attacks adjacent H from leaving group, LG bond goes to it, leaves, nuc (from backside attack) makes new bond to carbon that hydrogen left-concerted- stero chem inverts

Sn1

LG leaves, CC forms, shifts take place, NUC attaches itself - racemic mix

cl2 hv

free radical halogenation, 3* favored over all for radical, imitation, propagation, termination

3* OH

H-x