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Reply 1
I think it should be 3-bromo-2-methylpentane:smile:
Reply 2
That would be 3-bromo-2-methylpentane.

Remember, put a hyphen between all numbers and words, and a comma between all numbers.
Reply 3
DJkG.1
That would be 3-bromo-2-methylpentane.

Remember, put a hyphen between all numbers and words, and a comma between all numbers.

Ahh, thanks. I wasn't sure about that when I replied. I'd better change it now:biggrin:
Reply 4
B.Y.
Ahh, thanks. I wasn't sure about that when I replied. I'd better change it now:biggrin:


No worries. :smile:
Reply 5
Isn't that 3-bromo-4-methylpentane

?

Why do you start at one end to get 3-bromo and then start at the other end to get two. How is it you are going from right to left then left to right; I thought you have to keep it constant in the chain, and keep going from right to left, and not then change.:s-smilie:

sorry about that ramble.
Reply 6
MGIL
Isn't that 3-bromo-4-methylpentane

?

Why do you start at one end to get 3-bromo and then start at the other end to get two. How is it you are going from right to left then left to right; I thought you have to keep it constant in the chain, and keep going from right to left, and not then change.:s-smilie:

sorry about that ramble.


No we didn't start at one end and then the other. Maybe you should draw the structure out in a piece of paper...
Reply 7
I think I should but I can't find a pen:o:
MGIL
Isn't that 3-bromo-4-methylpentane

?

Why do you start at one end to get 3-bromo and then start at the other end to get two. How is it you are going from right to left then left to right; I thought you have to keep it constant in the chain, and keep going from right to left, and not then change.:s-smilie:

sorry about that ramble.


You prioritise alphabet in this case, then you try to keep the numbers lowest (ie. 3 and 2, not 3 and 4). This would mean stating the bromo first, as it's 'b' in the alphabet, and but keeping it in numerical order isn't possible after doing this, as you've already used alphabet. When there's 2 methyls, for example, it would just be 2,3- dimethylpentane.
Reply 9
I drew it out.

The thing I want to ask: is it okay to go from 3 to 2: are you allowed to go backwards in numbers?

Because I would have kept constant from right to left and said 3-bromo-4methylpentane.


My teacher never tells me these rules:mad:
Thank you. I also don't get this. if I have three methyl attatched like this:
CH3CH(CH3)CH2C(CH3)2CH3

Is that then 2,4,4-methylpentane, or do you have to do it differently if there are more than one?
Hahaha. Not noticed that three is in the middle of the chain yet and would be in position 3 from either side? :nah:
definite_maybe
Thank you. I also don't get this. if I have three methyl attatched like this:
CH3CH(CH3)CH2C(CH3)2CH3

Is that then 2,4,4-methylpentane, or do you have to do it differently if there are more than one?


I think that would be 2,2,4-trimethylpentane. So there are more of the lower number.
MGIL
I drew it out.

The thing I want to ask: is it okay to go from 3 to 2: are you allowed to go backwards in numbers?

Because I would have kept constant from right to left and said 3-bromo-4methylpentane.


My teacher never tells me these rules:mad:


Whichever way around it is, go alphabetically and use the smallest numbers possible.

Like 3,4-dimethylpentane is impossible; it should be 2,3-dimethylpentane.
Also, instead of 2-methyl-4-bromopentane it would be 2-bromo-4-methylpentane because they're in the same relative positions but the bromo- prefix is first alphabetically. xx
Reply 14
What would you name

CH3CH2CH(BR)CH(CH3)CH2CH3
FlowerFaerie087
I think that would be 2,2,4-trimethylpentane. So there are more of the lower number.


Yes, sir! You are correct.
Remember the 'trimethyl' becuase there are 3 seperate CH3 groups. Never really encountered anything with 4, but i think it'd probably be tetramethyl. (2 is di-, obviously)
B.Y.
It's 2,4,4-dimethylpentane. If there are three methyl groups attached to a carbon, a “tri" prefix should be added. If there are four, it should be "tetra", etc.

Is it not the case that the groups don't have to be attached to the same carbon? I swear you can say 1,2-dibromopropane. I'm sure I was taught that it was the total number of groups, not just the number on one carbon.
MGIL
What would you name

CH3CH2CH(BR)CH(CH3)CH2CH3


Either 3-bromo, 4-methylhexane or 4-bromo, 3-methylhexane.
They are the same compound. There may be standard ways of nomencrature in this instance, however at A-level both are acceptable.
Reply 18
SO you can go from 3 to 2(backwards)instead of going straight from 3 to 4.

ok:smile:
Reply 19
TwoTimesTwo
Either 3-bromo, 4-methylhexane or 4-bromo, 3-methylhexane.
They are the same compound. There may be standard ways of nomencrature in this instance, however at A-level both are acceptable.


no alphabet prioritising?

And what's nomencrature:confused: