quick q bout alkene/alkane reactivity (1 Viewer)

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

when u react cyclohexane with bromine water, do u get bromo-cyclohexane and HBr or do you get 1,2-dibromocyclohexane and hydrogen?

 

[inasero]

cyclohexane does not react with bromine water remember? only chclohexENE does
and in that case the first scenario is the one which occurs

 

[ND]

In the presence of UV light it reacts with it by substitution (IIRC).

edit: and yep i think it's the 1st one.

 

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

thanks.

 

[inasero]

In the presence of UV light it reacts with it by substitution (IIRC).

really how is that so? i thought cycloalkane was completely unreactive, uv light or no uv light

 

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

are cycloalkanes different to regular alkanes? cuz regular alkanes react w/ uv.

 

[inasero]

they do? hmmm an enigma to me...wheres shannon when u need her?

anyhows cycloalkanes have similar properties to alkanes except they differ saturucturally- the ends of an alkane chain link back onto itself to form a ring structure

 

[inasero]

hey yewon r ppl buying heaps of and for you? hehe i don't really like either but my mum is forcing me to eat them ^^;

 

[Frigid]

both chemicals react...
but in class we didn't do cyclohexane reacting under UV light (sunlight)...

yewon i forget the answer to your original question but gut instincts tell me its the first option, not the second.

 

[inasero]

o i c i c...john mu's summary says that the alkanes do react in presence of uv light, albeit very slowly

 

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

yes i know alkanes react.. it's jus u said cycloalkanes didnt'.. and it got me confused.. okay.. so cyclohexane will react wit bromine water in presence of uv, if slowly, to form bromocyclohexane and HBr...

hehehe... they're not forcing me to eat it.. but family friends and stuff keep bringing the stuff over.. i ate some... =P i like , not ew ew ew...
yeh.. but i'm staying away from bananas.. you stay away from bananas too, young man! ̲ ! haha...

 

[mercury]

LOL oops.... came too late.

Apart from some exceptions, alicyclic hydrocarbons go thru same reactions as the open-chain ones. Hmm..... they react VERY VERY slowly... and um in the case of cyclohexane, even if the substitution reaction does occur, my belief is it wont' be very stable. Cyclohexane itself, unlike cyclopropane and the smaller ones, is free of angle strain and torsional strain. So if you suddenly chuck this huge bromine atom onto it... even if the reaction does occur, the product will be very unstable as the conformation of cyclohexane would have to change, to adjust to the additional strain.

 

[inasero]

man, i wouldn't mind regular but this ȣڿ is just...(); it tastes so weird...

and i've been blending alotta banana milkshakes lately, average 3 a day...plenty of carbos and all the vitamins u need

 

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

thanks shannon =)

edit: too many bananas... =) hehehe...

 

[inasero]

so in english what ur saying is that cyclohexane won't usually react with bromine water right?

 

[mercury]

So in answer to the original question, macroscopically, u r likely not to see much happening And cycloalkanes undergo substitution reactions just like aliphatic alkanes, so it would unlikely to be 1,2-dibromocyclohexane and hydrogen

 

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

coolies =)
so wit propanes, butanes etc, would u see any decolourisation if exposed to uv light?

 

[mercury]

oh dear, i do type slow, dont' i, everyone's online.

in short: you just won't see much happening.

Hmm, for butanes and propanes and stuff, if u expose them to light long enough, you'll see something happening, it's damn slow.
we did it in class, and after two days, u could still hardly see much. (we did it with hexane)

 

[inasero]

eh take a chill pill yewon i dont think u have to know that deep

 

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

sheesh.. u left for two days? we did it outside cuz it stank up the room so much =P but we were in the sun.. and the hexane didn't do anything.. so i guess it all fits =)