OCR F324-June 2013 Chemistry

OP

Original post by D4rth

Really? I've never heard of that before, its not even in the book.

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it was a stretch and challenge :smile:

my turn

Reply 1483

JP.

6

I'm retaking this as I got a C in January due to SILLY mistakes! My revision starts today, any tips?

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Original post by otrivine

yes 1/2 marks

the last mark would have been that , where you said pharmacologically inactive, you had to state could lead to liver conditions such as hepatitis

you definitely dont need to know that it could lead to liver conditions

Reply 1485

OP

Original post by Zzzyax

you definitely dont need to know that it could lead to liver conditions

Hi

want to revise

It was in the mark scheme? of the legacy , maybe in old spec

Reply 1486

OP

when the ethanoic anhydride reacts with an alcohol, how does the bond break to form the methyl ehtanoate

Reply 1487

Original post by otrivine

when the ethanoic anhydride reacts with an alcohol, how does the bond break to form the methyl ehtanoate

the carbon oxygen single sigma bond breaks by heterolytic fission?, the bonding sigma pair goes to the oxygen atom, which then forms the ester bond with the CH3OH

(CH3COOCOCH3)so the products are CH3COOH and CH3COOCH3 plus H20

(edited 10 years ago)

Reply 1488

OP

Original post by Zzzyax

the carbon oxygen single sigma bond breaks by heterolytic fission?, the bonding sigma pair goes to the oxygen atom, which then forms the ester bond with the CH3OH

(CH3COOCOCH3)so the products are CH3COOH and CH3COOCH3

Thanks, I mean like you know with the Carboxylic acid and alcohol, you remove water and join them

how does it work with the acid anhydries and alchol

Reply 1489

Original post by otrivine

when the ethanoic anhydride reacts with an alcohol, how does the bond break to form the methyl ehtanoate

a Protien undergoes hydrolysis, expalin whether the amino acids produced are in a racemic mixture or of single optical isomer

Reply 1490

OP

Original post by Zzzyax

a Protien undergoes hydrolysis, expalin whether the amino acids produced are in a racemic mixture or of single optical isomer

The amino acids produced are racemic mixture, this is because the (chiral centre) carbon atom is attached to 4 different atoms or groups of atom, and hence, can form 2 isomers which means , 2 non super imposable images of each other, one isomer rotates plane polarised light clockwise while the other isomer rotates plane polarised light anticlockwise, so results in these two isomers/mixture cancelling each other out.

Reply 1491

Original post by otrivine

The amino acids produced are racemic mixture, this is because the (chiral centre) carbon atom is attached to 4 different atoms or groups of atom, and hence, can form 2 isomers which means , 2 non super imposable images of each other, one isomer rotates plane polarised light clockwise while the other isomer rotates plane polarised light anticlockwise, so results in these two isomers/mixture cancelling each other out.

i am sorry thats wrong, protiens are made from stereospecific enzymes

Reply 1492

OP

Original post by Zzzyax

i am sorry thats wrong, protiens are made from stereospecific enzymes

I see, and what does Stereospecific enzyme mean

but on page 53, does it not show optical isomers between amino acids?

Reply 1493

Original post by otrivine

I see, and what does Stereospecific enzyme mean

but on page 53, does it not show optical isomers between amino acids?

So all enzymes produce molecules of a specific optical isomer, so its called stereospecific

protiens are natural molecules
made from enzymes

Reply 1494

OP

Original post by Mus1995

Can someone explain Q 1(a)(iii)? http://www.ocr.org.uk/Images/79471-question-paper-unit-f324-rings-polymers-and-analysis.pdf

Hi, can you confirm Zzzyax asked a question about protein hydrolysis , I pretty sure , I am not sure but when a protein is hydrlysed a carbon atom is attached to 4 different variables for optical isomerism to take place and can form mirror images?

Reply 1495

OP

Original post by Zzzyax

So all enzymes produce molecules of a specific optical isomer, so its called stereospecific

protiens are natural molecules
made from enzymes

Yes but if it produes optical isomer it still forms mirror images which gives racemic.

I think you are getting confused

read this http://www.chemguide.co.uk/basicorg/isomerism/optical.html

(edited 10 years ago)

Reply 1496

Original post by otrivine

Hi, can you confirm Zzzyax asked a question about protein hydrolysis , I pretty sure , I am not sure but when a protein is hydrlysed a carbon atom is attached to 4 different variables for optical isomerism to take place and can form mirror images?

Jan 03 chain rings and spec, question 2d

Reply 1497

OP