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Author Topic: AS Chemistry Help Please  (Read 1185 times)

Offline vanibharutham

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AS Chemistry Help Please
« on: December 08, 2009, 01:58:20 pm »
Can some one please name the following compound,

the mark scheme says the answer is C and i dont think it is

i worked it out as this:

Take the highest priority groups on each carbon atom, which would be chlorine and methyl groups respectively

and because they are the same side it is a Z compound
hence i think that it is

(Z) 2-chlorobut-2-ene
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Offline MaNi_DaDuDe

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Re: AS Chemistry Help Please
« Reply #1 on: December 08, 2009, 02:59:38 pm »
Answer is C.

The 1st carbon is in CH3 on the bottom right.
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Offline vanibharutham

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Re: AS Chemistry Help Please
« Reply #2 on: December 08, 2009, 03:06:55 pm »
hey but dont u need to consider the seperate side groups on the double bonded ca


C = C

on the left carbon above there is a methyl group on top and a hydrogen on bottom. Highest priority = methyl
on the right carbon above there is a chlorine on top and a methyl group on bottom. Highest priority = chlorine

Because the two highest priority groups on each carbon are on the same side, that is, on top, on their respective carbons, the molecule surely should be a Z isomer?

I know the base name will be

2-chlorobut-2-ene
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Offline MaNi_DaDuDe

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Re: AS Chemistry Help Please
« Reply #3 on: December 08, 2009, 03:10:18 pm »
I do not understand what you mean.. I used the method taught to me in my IGCSEs.

What board you doing?

I did CIE AS last year. .
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Offline vanibharutham

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Re: AS Chemistry Help Please
« Reply #4 on: December 08, 2009, 03:13:29 pm »
Edexcel's New Specification (2008 onwards)

and what i was primarily asking was whether the compound an E isomer or a Z isomer?
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Offline MaNi_DaDuDe

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Re: AS Chemistry Help Please
« Reply #5 on: December 08, 2009, 03:16:53 pm »
Quote from: vanibharutham on December 08, 2009, 03:13:29 pm
Edexcel's New Specification (2008 onwards)

and what i was primarily asking was whether the compound an E isomer or a Z isomer?

Oh.

I'm sorry - we didn't do that in c
CIE.
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Offline vanibharutham

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Re: AS Chemistry Help Please
« Reply #6 on: December 08, 2009, 03:20:30 pm »
thanks anyway :)
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nid404

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Re: AS Chemistry Help Please
« Reply #7 on: December 08, 2009, 04:01:27 pm »
it's z isomer....cuz it's trans
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Offline vanibharutham

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Re: AS Chemistry Help Please
« Reply #8 on: December 08, 2009, 04:05:16 pm »
yay,

so is the mark scheme wrong in saying E?
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nid404

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Re: AS Chemistry Help Please
« Reply #9 on: December 08, 2009, 04:09:26 pm »
 If both of the substituents of higher priority are on the same side, the arrangement is Z; if they are on opposite sides, the arrangement is E.


my bad..it's gotta be E
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Offline vanibharutham

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Re: AS Chemistry Help Please
« Reply #10 on: December 08, 2009, 04:21:53 pm »
...
what are the highest priority groups on each carbon?

the left carbon has the methyl group as its highest priority
and the right carbon has the chlorine as its highest priority?

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nid404

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Re: AS Chemistry Help Please
« Reply #11 on: December 09, 2009, 04:18:55 am »
Quote from: vanibharutham on December 08, 2009, 04:21:53 pm
...
what are the highest priority groups on each carbon?

the left carbon has the methyl group as its highest priority
and the right carbon has the chlorine as its highest priority?



methyl group is the substituent with higher priority, but they r on opp sides, hence it is E
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