OCR A Chemistry F324 Rings, Polymers and Analysis Thu 26 Jan 2012

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I got that (except I did step 2 and step 1 the other way round which I'm sure won't matter). However I said the halogen carrier was FeCl3, instead of AlCl3, think that will be acceptable?

Yes

Reply 981

Lindizya

I lost about 15 marks WTF at the diamer or however you soell it question I nearly died lol

Reply 982

fudgesundae

Original post by The medjai

why would we need to prove it was carbonyl? The guy said it was either aldeyde or ketone.

He said he thought it might be one of those 3. The guy could have been completely wrong.

Reply 983

Confused94

The question only said there was a c=o bond - which meant t could be an aldehyde ketone OR ester, so you needed to make sure by adding 2,4-DNPH.....I think.

Reply 984

Yarpie

Original post by Confused94

For the 3 step reactions, did it matter whether you put the chlorine or amine group on first? :s

Only thing that matters is going from NO2 first to NH2. Chlorine can come before or after that or even in between but NO2 must be before NH2. I don't see how Cl would change the reaction so that is my guess anyway.

Reply 985

Crabbiey

Original post by Lindizya

I lost about 15 marks WTF at the diamer or however you soell it question I nearly died lol

DX I know - that question just threw me! But I worked it out after a few seconds and it still took me ages to draw!

That, and I kept on having blanks. Such as forgetting abot AlCl3 for ages!

Reply 986

lukas1051

Original post by chemicalX

Arrgghh you can't reduce a carboxylic acid people!!!!! It's even in the book! THERE WAS AN ERROR IN THR EXAM!!! Arghhhhhhh

Original post by Yarpie

Uh... yes it does matter? That's the point of phenol and the alternating delta negative and delta positive carbons. It only reacts on the delta positive carbons which are at 2,4 and 6.

Carbon 4 was already reacted so you had to draw Bromine on carbon 2 and 6.

Surely the rest of the molecule would have affected the electronegativities though? And I'm pretty sure you can get phenol with groups substituted elsewhere, they're just not as common.

(edited 12 years ago)

Reply 987

rogersnm

Original post by chemicalX

Arrgghh you can't reduce a carboxylic acid people!!!!! It's even in the book! THERE WAS AN ERROR IN THR EXAM!!! Arghhhhhhh

You can reduce them using Lithium tetrahydridoaluminate however it's not in our unit, but that doesn't really matter, you can still answer the question.

Reply 988

fudgesundae

Original post by lukas1051

Yes you can. You can oxidise an alcohol to an aldehyde, and then to a carboxylic acid, therefore you can reduce a carbxylic acid to an aldehyde and then an alcohol. It is in the book too on the synthesis diagram.

Sure the rest of the molecule would have affected the electronegativities though? And I'm pretty sure you can get phenol with groups substituted elsewhere, they're just not as common.

On a mark scheme with a similar question, they allowed any number of bromines substituted anywhere.

Reply 989

Yarpie

Original post by chemicalX

Arrgghh you can't reduce a carboxylic acid people!!!!! It's even in the book! THERE WAS AN ERROR IN THR EXAM!!! Arghhhhhhh

You can dehydrate it and then reduce the aldehyde group. But you can reduce a carboxylic acid but it's above A-level Chemistry.

Reply 990

hockeyjoe

just one question, for the last question, was the structure:

CH3CH2COOCH2C(CH3)3 or CH3CH2CH2COOC(CH3)3?

Reply 991

Yarpie

Original post by lukas1051

Yes you can. You can oxidise an alcohol to an aldehyde, and then to a carboxylic acid, therefore you can reduce a carboxylic acid to an aldehyde and then an alcohol. It is in the book too on the synthesis diagram.

Surely the rest of the molecule would have affected the electronegativities though? And I'm pretty sure you can get phenol with groups substituted elsewhere, they're just not as common.

That is a very good point. In that case I have no idea and that I pray you get the marks.

Reply 992

wig44

I don't know why people think boundaries will be high. Irrespective of whether or not you found this paper hard, it was harder than previous papers and the format felt 'different'. I'm sure boundaries will not be higher than previous years and wouldn't be surprised if they were lower. My chemistry teacher agreed with the class that it was not an easy paper compared to previous papers of this spec.

The last 10 marker was a joke though, it really should have been more difficult.

Reply 993

VQG

Original post by Dreamweaver

Decent paper - expecting slightly lower than usual grade boundaries. Lost 1 mark on the first question and 2 marks on the synthesis question. How did everyone else find it?

Ester was (CH3)3CH2COOCH2CH3

Wasn't the peak with integration 9 a singlet?

Reply 994

Yarpie

Original post by hockeyjoe

just one question, for the last question, was the structure:

CH3CH2COOCH2C(CH3)3 or CH3CH2CH2COOC(CH3)3?

In bold.

Reply 995

wig44

Original post by hockeyjoe

just one question, for the last question, was the structure:

CH3CH2COOCH2C(CH3)3 or CH3CH2CH2COOC(CH3)3?

first one

Reply 996

Messi3

on the changing isoelectric point functional group question, is it ok to put cooh and nh2, or did you have to name them ie. carboxylic acid and amine?

Reply 997

hockeyjoe

Original post by Yarpie

You can dehydrate it and then reduce the aldehyde group. But you can reduce a carboxylic acid but it's above A-level Chemistry.

this...you can reduce it. You can't reduce it with sodium borohydride, but you can reduce it. The question didn't specify the reducing agent, it just said reduce.