alkenes and alkynes ochem midterm 2

what alkene rxn has X2 as the reagent and what is the mech, regio and stereochem

the concerted mechanism the alkene acts as a nucleophile and attacks the partial pos of the Br2 which creates a bromonium ion and a loss of LG to create BR-.

then there is another nuc attack in an SN2 tyope process, a backside attack, where the Br- attacks the more substituted carbon of the bromonium ion, leading to anti-addition of bromine to the alkene.

may produce a pair of EN and an inversion of configuration

what is thought process for Elimination vs substitution rxns

what are the rxn, mech, regio and stereo for alkene

hydro halogenation

acid catalyzed hydration

hydroboration oxidation

oxymercuration demurcuration

what rxn has Br2 and H20 as the reagent and what is the mech, regio and stereochem

halohydrin formation

same concerted mechanism as halogenation where the alkene forms a bromonium ion

then there is a nuc attack by water at the more substituted side , resulting in the addition of a bromine atom and a hydroxyl group to adjacent carbons in anti configuration.

may produce pair of EN and an inversion of confiuration

what is the rxn with MCPBA and H3o + what is stereo

anti dihydroxylation (adding 2 OH groups)

the alkene creates an epoxide from MCPBA which is then protonated by H3O+ and then the water acts as a nucelophile ot open the ring resulting in the addition of hydroxyl groups in an anti configuration across the alkene.

this is can create a pair of En and have an inversion of configuration

what is the rxn with OsO4 and H2O2 and stereo

syn dihydroxylation adding syn Oh groups

The reaction involves the alkene being treated with OsO4, forming a cyclic osmate intermediate, which is then hydrolyzed by H2O2 to yield two hydroxyl groups on the same face of the alkene, resulting in syn addition. This reaction can create a pair of enantiomers and may exhibit overall retention of configuration.

what is the alkene rxn with o3 and DMS

ozonolysis

where each c-c double bond is replaces with c-o double bonds

how can you to an alkyne from alkyl dihalides

by using 2 eq of a very strong base you can have two E2 rxns

what terminal alkene rxn with NaH or NaNH2 with an alkyl halide

acetylide formation or adding a carbon chain to an alkyne

This process involves the deprotonation of a terminal alkyne, allowing for subsequent nucleophilic substitution with the alkyl halide.

what rxn with H2 and Pt for an alkyne and lindlar’s catalyst

catalytic hydrogenation results in an alkane

if you use lindlars catalyst you stop at the cis alkeneinstead of forming an alkane.

what is the alkyne rxn if you use Na and NH3

The reaction involves dissolving metal reduction, which converts alkynes to trans alkenes.

what is the alkyne rxn if you use HgSo4, H2SO4, and H2O

The reaction is known as hydratation of alkynes, leading to the formation of a ketone. where the ketone is formed at the more substitued position

if the alkyne is not symmetrical must draw botth forms

what is the rxn for an alkyne with HX as the reagent and what is regio chem

hydrohalogenation

where the halide is added at the more substituted spot (mark)

what is the mechanism for tautomerization (both acid and base)

the enol attacks the H3O^+ to form ketone, (has CC intermediate) or base abstracts a proton from enol to form the carbonyl compound.

what rxn with 9 BBN or R2BH and naOH and H2O2

what is regio and stereo

hydroboration oxidation of alkyne

it adds an aldehyde at the less substituted position if terminal alkyne

but if internal alkyne it will yield ketone

it is anti mark and syn

what rxn with xs X2 or 1 eq X2

halogenation of alkynes

the addition occurs twice in excess or once in 1 eq of the halogeen

what rxn for alkyne with O3 and H2O

ozonolysis of alkynes

for an internal alkyne it creates two carboxylic acids

but for a terminal alkyne it creates a carboxylic acid and CO2