The Student Room Group

Buta-1,3-diene...:S

In the mark scheme it says that the empirical formula is:

CH3CH=CHCH2CH3

which really confused be cos I would have thought that there would have been 4 Carbons due to the "buta", not 5.

Also, diene...does that mean there are 2 double bonds cos the name for the alkene functional group is -ene, so I would have thought that this was the case...obviously not and I fell stupid cos my exam's tomorrow and I dont know this!!...AARRGGHH!!!!

Thanx in advance Xxx :awesome: 8D
Reply 1
Jaz8
In the mark scheme it says that the empirical formula is:

CH3CH=CHCH2CH3

which really confused be cos I would have thought that there would have been 4 Carbons due to the "buta", not 5.

Also, diene...does that mean there are 2 double bonds cos the name for the alkene functional group is -ene, so I would have thought that this was the case...obviously not and I fell stupid cos my exam's tomorrow and I dont know this!!...AARRGGHH!!!!

Thanx in advance Xxx :awesome: 8D


CH3CH=CHCH2CH3
That is just pent-2-ene. Are you sure you haven't read the markscheme wrong?
Reply 2
i bet its a mistake in the mark scheme. if you type the name of the molecule into google images then it will come up with a diagram of the molecule. hope that helps!
No, buta-1,3-diene is CH2=CH-CH=CH2, what you've drawn is pent-2-ene
Reply 4
Hmm, it looks like that formula is just wrong, and it's structural rather than empirical. You're right about the 4 carbons and two double bonds - the correct structural formula should be CH2=CHCH=CH2 (and thus an empirical formula of C4H6).
Reply 6
Yeah I think the mark scheme may be wrong...I drew out what I thought it was before checking the mark scheme and I got what you're all getting...phew!!!!!

Thanks!!!!!!! :awesome:
Reply 7
Oh...so yeah...now I feel like a right eejit...I was looking at the wrong answer....
Sometimes I astound myself with my stupidity lol XD

Thanks for your help anyway!! :awesome:
As an aside: Been a while since I've had to use IUPAC systematic nomenclature, but I;m fairly certain we were taught it was but-1,3-diene, rather than buta-1,3-diene, I'm not sure which is correct or if it matters?

Tbh, I could be remembering wrong, it was quite distracting when certain people in the class kept laughing at the word "butanal" because, and I quote, "It looks like butt anal LOL!" :rolleyes:
Revd. Mike
As an aside: Been a while since I've had to use IUPAC systematic nomenclature, but I;m fairly certain we were taught it was but-1,3-diene, rather than buta-1,3-diene, I'm not sure which is correct or if it matters?


You are correct. But-1,3-diene is more correct than buta-1,3-diene, unless I've never heard of having the extra 'a' there.
Just looked it up, for the diene, the root is indeed buta.
Supergrunch
Hmm, it looks like that formula is just wrong, and it's structural rather than empirical. You're right about the 4 carbons and two double bonds - the correct structural formula should be CH2=CHCH=CH2 (and thus an empirical formula of C4H6).


No, the empirical formula is the simplest possible ratio... in this case C2H3
charco
No, the empirical formula is the simplest possible ratio... in this case C2H3

Ah yes, thanks for the correction.
I think it is H2C = CH - CH - CH2. Hope that helps!
Original post by catherineabraham
I think it is H2C = CH - CH - CH2. Hope that helps!


I imagine that the OP is very grateful for the help ....


.... considering that they asked over five years ago! :eek: