quick q bout alkene/alkane reactivity (2 Viewers)

[+:: $i[Q]u3 ::+]

shut up and u take a chill pill.. =)

 

[inasero]

ohhh.....*sob**sniff*

 

[mercury]

I want milkshake
mum's too busy..... oh, i'll be a good girl and make myself some.

LOL yewon is willing to learn CHEM.... that is GOOOOOOOOOOOD thing teach me phys yewy...

 

[inasero]

haha too l8

 

[mercury]

don't be mean yewy
he's trying to be nice.

 

[spice girl]

*sigh* pplz stop having fun...get offline and study!

 

[+:: $i[Q]u3 ::+]

er... sn2! sn2! haha.. i don't even know what that is...
phys??? pfft... u'll be doing enuf phys next year =) and then u can finally explain to me what those gaussian thingys actually mean =)

 

[mercury]

hahahahaha... memories.... sn2 rocks man
go do more chem, u'll love it.
gaussian surfaces? man........ kickass stuff i only know the name though

 

[+:: $i[Q]u3 ::+]

Originally posted by spice girl
*sigh* pplz stop having fun...get offline and study!

hehehe...

(oh btw inasero.. get used to it ^^ jkjk..)

 

[mercury]

yeah we should eh..... btw, who r u spice girl? rn't u uni person now?? hmm, i don't know if i should bother do phys
i'd rather do biochem and physiology and stuff... of coz maths and computing.

 

[mercury]

yewy is ur msn still stuffed..... hmm.... nvm, i know where to find u now where-else.....hehe

 

[inasero]

asdf

 

[iambored]

Originally posted by mercury
1,2-dibromocyclohexane and hydrogen

ah, there's the answer, but where's the hydrogen from?

 

[ND]

Reacting by substitution is exactly that, the Br takes the place of teh H.

 

[+:: $i[Q]u3 ::+]

Originally posted by iambored
ah, there's the answer, but where's the hydrogen from?

lol.. that's not the answer. it's um.. bromocyclohexane and HBr...... ~~~ right? ah well.

 

[ND]

Yep, cos i think the UV light breaks up the Br2 molecule, and one of the free radicals reacts with a H, breaking it away, and the other takes the place in the cyclohexane.

 

[phenol]

this is conditional

if bromine concentration in Br water is high then u get the trans dibromo

if bromine concentration is relatively low then you get the bromohydrin Br and OH adding accross the double bond together with HBr formation

the mechanism for the former is a bromonium ion intermediate and at this point either the water or bromine can attack so u can get either dibromo or bromohydrin

there's competition between the two

 

[iambored]

what? but when i write the equation, i draw
1,2-dibromocyclohexane

the ring with the double bond broken and the 2 Br attached

 

[phenol]

for the UV, indeed it goes free radical mech

Br radicals attacking the ring but how the H comes off is slightly more complicated (a bit of arrow pushing if you get what i mean)

i doubt the speed of this though as the alkane/water interface is limited. unless you agitate it, the reaction will be rather slow

 

[phenol]

Originally posted by iambored
what? but when i write the equation, i draw
1,2-dibromocyclohexane

the ring with the double bond broken and the 2 Br attached

that's not wrong, just not the whole story

it would be if you do Br2/CCl4 as the reagent

water is nucleophilic and can attack as well as the bromide ion