Exam Suggested Solutions

[iamdan08]

i agree, i always thought u start naming from the end closest to any functional group?

edit : according to the nelson book the carbons in the main chain are numbered from the end nearest the first chlorine

Thats what i thought (and did) as well!

[pinchies]

my 2¢
i name it by structure lowest first (i.e. -ene, methyl-, etc) then other functional groups (chloro- amino- wacko-)
does anyone have a reason why 2-methyl-5-chloro-heptane is wrong?

[Collin Li]

does anyone have a reason why 2-methyl-5-chloro-heptane is wrong?

The hyphen in between "chloro" and "heptane" shouldn't be there.

[orangez]

Freaking hell, I didn't see that chlorine atom 

[ben4386]

i dont get why u guys called it 2 methyl 5 chloroheptane, dont u always name from the end closest to the functional group?, annie the ref is page 188

[Collin Li]

i dont get why u guys called it 2 methyl 5 chloroheptane, dont u always name from the end closest to the functional group?, annie the ref is page 188

Wouldn't 2 and 5 be closest? The alternative is 3 and 6.

[ben4386]

yes but you always start naming from the end nearest the functional group

[Collin Li]

Functional groups include side chains. They aren't special.

[Rayle]

However, it's still a chloroalkane, and not a alkylalkane (ie. this doesn't exist, AFAIK), and hence shouldn't it be named using the systematic name as such?

The carbons on the main chain are numbered from the end nearest the first chlorine.

[username]

Do you get full marks if you put "if x=324234" or something for part b if you weren't able to find part A? Or just one mark?

[Collin Li]

You guys are complicating naming. Naming is supposed to be simple, and not riddled with loopholes and rules like the law is.

Name from the end nearest to a group (sidechain or functional group).

Do you get full marks if you put "if x=324234" or something for part b if you weren't able to find part A? Or just one mark?

Yes, if you show working.

[bubbles]

So: " 3,6,-chloro-methylheptane " which is what i wrote would be wrong?

[Collin Li]

So: " 3,6,-chloro-methylheptane " which is what i wrote would be wrong?

Yes, for two reasons:

i) the indication of position is incorrect, it would be: 3-chloro-6-methylheptane
ii) you numbered from the wrong end, it should be: 5-chloro-2-methylheptane

[onlyfknhuman]

dont you start frmo the side CL is from, and wasnt their 2 methyl branches

so itwas 6.6 dimethyl 2,chloroheptane or hexane cant remmber

[Collin Li]

No. The second "methyl" group you speak of can be counted as part of the main chain, hence making it a 7 carbon chain, rather than a 6 carbon chain.

You start from the side closest to any group, whether it be a chloro group or a methyl group.

The chloro group, according to Mao's diagram, is on the 3rd carbon away from the end, so instead you'd number at the end closer to methyl (2nd carbon away).