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OCR F324-June 2013 Chemistry

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Reply 2500

mrmccarl

Original post by Varsh05

Do we need to know details/structure on omega 3 and omega 6- fatty acids?

no not really...just cis and trans form and their effects on the body ie LDL and HDL.

Reply 2501

Onkar-M

guys- June 2012, question 4c
Benzaldehyde + CH3COCH3 - I don't know how they got their answer.
Like I get the condensation bit, but they've got C=C bonds in there?!

Reply 2502

kitkat95

Original post by Varsh05

It's better to draw the mechanism than to describe in words.
Mechanisms are more likely to gain you most marks,if not all.

I know that some of the questions ask you to draw out the mechanism, but I'm sure I've seen questions where it gives you lines and asks you to describe what is happening, and I have no idea :biggrin:

Reply 2503

otrivine

Original post by thers

My next question is: Name the molecule above [50]

Spoiler

which structure above :smile:

Reply 2504

Zzzyax

what is transesterification ?

Reply 2505

_HabibaH_

Original post by k54g00

How can H2N-(CH2)4-NH2 be synthesised from Cl-(CH2)4-Cl??

Excess NH3/Ethanol solvent and Reflux

Reply 2506

V__005

Original post by JimmyA*

Yes we do especially stuff like dehydration reactions.

Are the reagent and conditions for that: H2SO4 catalyst and Heat under reflux? :s-smilie:

Reply 2507

thers

Original post by otrivine

which structure above :smile:

The one I just asked about the chiral carbons. Was only joking lol.

Reply 2508

D4rth

Well Im done for the day.

Good luck guys!
To all the regulars: you guys clearly know your stuff, so stay calm, think logically and you'll achieve those high grades!!

Posted from TSR Mobile

Reply 2509

V__005

Original post by kitkat95

I know that some of the questions ask you to draw out the mechanism, but I'm sure I've seen questions where it gives you lines and asks you to describe what is happening, and I have no idea :biggrin:

Sometimes they give you a huge space and a few lines.
But even then,mechanism will always give you the marks.

Reply 2510

_HabibaH_

Original post by thers

my next question is: Name the molecule above [50]

Spoiler

yusssss! I'm so heppy i got the answer right yayayayaya! :biggrin:

Reply 2511

chiny94

does metal carbonate only work with carboxylic acid in phenol?

Reply 2512

otrivine

Original post by D4rth

Well Im done for the day.

Good luck guys!
To all the regulars: you guys clearly know your stuff, so stay calm, think logically and you'll achieve those high grades!!

Posted from TSR Mobile

thank you , you too :smile:

!!

all the best!!

speak tomorrow afternoon

Reply 2513

Zaphod77

Original post by _HabibaH_

Excess NH3/Ethanol solvent and Reflux

That came up in a paper, but where is that mentioned in the book? I couldn't find it :s-smilie:

Reply 2514

V__005

Original post by mrmccarl

i believe so...but its not too difficult to remember as long as you remember the carbocation. and heterolytic fission.

Electrophilic addition and nucleophilic substitution are the main ones from AS,right?

Reply 2515

otrivine

Original post by thers

The one I just asked about the chiral carbons. Was only joking lol.

I think I will get heart attack if I see that and asked us to name it, like you said I think my heart will come out of me :tongue:

Reply 2516

Jodie_668

Original post by kitkat95

Can someone please tell me how to describe nucleophilic substitution and addition, in my revision notes it say:
Nucleophilic addition: the C=O bond is polar, the nucleophile attacks the electron deficient carbon forming a new covalent bond and that an addition reaction occurs across the double bond. Is this right? because it doesn't seem like a very scientific explanation.
And what would the description of nucleophilic sub be?

Nucleophilic addition: The lone pair of electrons is attracted to the delta positive carbon so forms a dative covalent bond with the carbon. The pi bond between the C=O breaks and the pair of electrons goes to the oxygen so that it becomes negative. The lone pair of electrons on that oxygen are then attracted to the delta positive hydrogen in a water molecule so forms a dative covalent bond whilst the sigma bond between the H-O in the water molecule breaks and the electrons go to the oxygen.

Nucleophilic substitution: The positively charged ion is attracted to the delocalised pi electrons on benzene. Two electrons are lost from the delocalised pi system to form a covalent bond between a carbon and the nitrogen/halogen. Two electrons from the C-H bond are moved to restore the full delocalised system of 6 pi electrons so the proton is lost.

Hope that is ok :smile:

There might be bits missing, but I'll doubt they'll ask us to describe in words anyway.