OCR Chemistry A F324 Rings, Polymers and Analysis Tue 19 June 2012

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Reply 1580

LGrosvenor101

Original post by racheatworld

Me too

I said that the C=0 bond can break by radiation - is that fine?

Reply 1581

nereik6794

Original post by mazE12

****, for the last question i put CH3CH2C6H5OCOCH3. basically i put the benzene in the middle rather than the end. will i still get some marks?

The structure is worth about 4 marks but you will get a fair few marks for explaining splitting patterns, integration traces, chemical shift etc

Reply 1582

Tateco

Original post by racheatworld

It was split into a multiplet of 6, therefore there were 5 H's in the adjacent environment. The adjacent environment was the same environment on the benzene ring.

Ugh, that is what screwed me over and make me put a methylbenzene attached to the other carbons and ester link.

Should hopefully only lose a couple of marks because the rest of the question was fine and mine all added up to 164 etc.

Reply 1583

YB101

The only exam to go well out of the 9 I've already had! So happy!x

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Reply 1584

SmithytheDrummer

Original post by racheatworld

Probably not unless you said photodegradable or to split into fragments by light energy.

Thinking back I think I did put that is broken down by light as well anyway :smile:

Reply 1585

Konshi

Original post by nereik6794

Naturally occuring chemicals tend to be a single optical isomer which helps to phameceutically form a single optical isomer also.

Excuse my spelling. haha

Gah. I put that it would yield the desirable enantiomer, in the same orientation as the natural one. Don't think I'd get the mark for that :/

Reply 1586

racheatworld

Original post by Tateco

I was also staring at that multiplet peak for some time, in the end I did trial and error until they all matched up.

I think you'd only lose 1 mark.

Reply 1587

Aa234

Original post by Gman1234

and the question after, reduce using NaBH4 (aq), ketone group reduces into alcohol. Then add conc H2SO4 and heat under reflux, alcohol and carboxyl group react to make ester?

That was a ketone? F**k! I put aldehyde!!

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Reply 1588

Tateco

Original post by niaghez

okay so for the ester i got C6H5CH2CH2COOCH3 is that okay?
EXCEPT i accidently did the O=C-O ester linkage by putting the C=O on the CH2 side...
would i lose a mark?

Normally they are really good with giving the first 7 or so marks for explaining what all the peaks represent and then the last two are harder to get and you have to pretty much get the molecule spot on.

Reply 1589

Gman1234

What did everyone get for the reagents for turning -CL into -NH2?

Reply 1590

OT93

Original post by jamescook

ester i got was CH3-CO-O-CH2-CH2-C6H5

anyone else?

I got this as well. Though I thought there should be 3 different peaks for the benzene ring, anyone?

Reply 1591

racheatworld

Original post by LGrosvenor101

I said that the C=0 bond can break by radiation - is that fine?

Not sure whether you'd need light energy in there, but the C=O part is correct.

Reply 1592

godknows

guys do you think the grade boundaries will be higher/lower than jan 2012?

Reply 1593

VQG

That was a seriously easy paper. Grade boundaries surely higher than January? :frown:

51 - A
46 - B
42 - C

What does everyone think?

Reply 1594

niaghez

Original post by Aa234

That was a ketone? F**k! I put aldehyde!!

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it was aldehyde!! it had a H but you dont show it on carbon skeleton cos its come up in the past!!

Reply 1595

nereik6794

Original post by Konshi

Gah. I put that it would yield the desirable enantiomer, in the same orientation as the natural one. Don't think I'd get the mark for that :/

At least you know you wrote an answer on the right tracks, you may get the mark! Don't worry, it is only a single mark + this had some challenging stuff in it; the grade boundaries will certainly be lower than Jan 12.

Reply 1596

racheatworld

Original post by Aa234

That was a ketone? F**k! I put aldehyde!!

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It was an aldehyde! Don't worry.

Reply 1597

OT93

Original post by ReTurd

There were 27 carbon atoms and 2 chiral carbons right???

Google says 27 carbons, with 8 chiral carbons.

Reply 1598

Tateco

Original post by racheatworld

I was also staring at that multiplet peak for some time, in the end I did trial and error until they all matched up.

I think you'd only lose 1 mark.

Wow that's optimistic :tongue:

But yeah I obviously just missed something with the other splittings at the end in the mad rush and was pleased with myself for getting something with 5 protons on an adjacent carbon. The only questions that went wrong were the end of this, the KOH one and the conditions for aliphatic.