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Reply 1540
Original post by Mus1995
I do. :smile:

Show me a question and I'll show you how to do it.


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Jan 2010- 5b II
Impurity with molecular formula C10H11NO3
Reply 1541
should we draw the structure in [ ] when they say draw two repeated units of a polymer?
Reply 1542


ImageUploadedByStudent Room1371394490.463226.jpg

Here you go. Ask if you don't understand/can't read anything. :smile:


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Reply 1543
Original post by amin666
should we draw the structure in [ ] when they say draw two repeated units of a polymer?


Yeah. Like this. :smile: ImageUploadedByStudent Room1371394591.763824.jpg


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Reply 1544
Original post by Mus1995
Yeah. Like this. :smile: ImageUploadedByStudent Room1371394591.763824.jpg


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what does the "n" stand for and does it have to be included?
Reply 1545
Original post by Onkar-M
Jan 2010- 5b II
Impurity with molecular formula C10H11NO3


Bit messy. It's another further substitution. :smile: ImageUploadedByStudent Room1371395050.846405.jpg


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Reply 1546
Original post by Mus1995
Yeah. Like this. :smile: ImageUploadedByStudent Room1371394591.763824.jpg


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I always used to draw the brackets but the mark schemes always say to ignore so I've stopped. Might do it in the exam though just in case they want it in our paper.

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Reply 1547
Original post by D4rth
I always used to draw the brackets but the mark schemes always say to ignore so I've stopped. Might do it in the exam though just in case they want it in our paper.

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It says ignore which means you can do it, it won't dock you marks. I think it is good practice. You will still get the marks! :smile:

Original post by kuku2013
what does the "n" stand for and does it have to be included?


It represents the fact this repeat unit continues n times, as it is a long polymer! So just imagine this repeat unit continuing.
Reply 1548
Guys can anyone tell me all the reactions you need to remember ?? And the conditions for each one please ??
Reply 1549
Original post by Mus1995
Can you link me to the paper? I need to see the question. :smile:


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http://www.ocr.org.uk/Images/58126-question-paper-unit-f324-rings-polymers-and-analysis.pdf

Question 4a(ii) :smile:
Reply 1550
Original post by tom2013
Guys can anyone tell me all the reactions you need to remember ?? And the conditions for each one please ??


I've attached a list of all the conditions and reagents I've been using to revise, think almost everything is covered in there:smile:

ImageUploadedByStudent Room1371397356.786392.jpg

You can probably ignore the first one :smile:


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(edited 10 years ago)
Original post by amsss
I've attached a list of all the conditions and reagents I've been using to revise, think almost everything is covered in there:smile:

ImageUploadedByStudent Room1371397356.786392.jpg




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Hey, is the free radical equation on the spec? Because it's nowhere in the book or in the new spec questions? Thanks.
Reply 1552
Original post by _HabibaH_
Hey, is the free radical equation on the spec? Because it's nowhere in the book or in the new spec questions? Thanks.


I'm not sure it actually is, we were just told it should be assumed knowledge from AS. Don't think I've seen any questions on it though so wouldn't worry about it to be honest :smile:


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Reply 1553
Original post by Mus1995
Bit messy. It's another further substitution. :smile: ImageUploadedByStudent Room1371395050.846405.jpg


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Thank you!
Ps nice emoticons :wink:. Haha
Original post by tom2013
Guys can anyone tell me all the reactions you need to remember ?? And the conditions for each one please ??


There are LOADS so forgive me if I miss any.

Nitration of Benzene: C6H6 + Concentrated HNO3 ==> C6H5NO2 + H+
Conditions: Reflux + Concentrated H2SO4 Catalyst
Formation of electrophile: H2SO4 + HNO3 ==> HSO4- + NO2+ = H2O
How the catalyst works: H+ = HSO4- ==> H2SO4
Halogenation of Benzene: C6H6 + Cl2/Br2 ==> C6H5Cl/C6H5Br + HCl/HBr
Conditions: AlCl3/AlBr3 Catalyst
Reduction of Nitrobenzene: C6H5NO2 + Sn/Conc. HCl (6[H]) ==> C6H5NH2 + 2H2O
Conditions: Reflux
Diazotisation: C6H5NH2 + Concentrated HCl + Concentrated HNO2 ==> C6H5N2+Cl- + H2O
Conditions: Under 10 degrees celcius
Coupling: C6H5N2+Cl- + Phenol ==> Azo Dye
Conditions: Alkaline conditions, under 10 degrees celcius

Test for Carbonyls: Add 2,4-DNPH forms orange precipitation which is addition-elimination reaction
Identifying carbonyl: Filter and recrystallise the precipitate and measure melting point, compare against known values.
Distinguishing Aldehyde or Ketone: Add Tollen's reagent which forms a silver mirror if aldehyde is present.
Reducing aldehydes/ketones: Add NaBH4 which is Nucleophilic addition reaction

Formation of polyester: Carboxylic acid + alcohol monomers
Formation of polyamide: Carboxylic acid + amine monomers

Primary Alcohol + [O] ==> Aldehyde (Distillation)
Primary Alcohol + 2[O] ==> Carboxylic acid (Reflux)
Secondary Alcohol + [O] ==> Ketone (Reflux)

Halogenation of alkenes: Add HCl/HBr??
Test for Alkenes: Add Br2 ==> Colour changes from orange to colourless
Test for Phenol (or any OH group): Add Na ==> Effervescent produced as Hydrogen released
Phenol + Br2 ==> 2,4,6-tribromophenol (white precipitate)

Fatty acid + Glycerol ==> Triglyceride

Acid Hydrolysis: Add H2O with presence of acid catalyst under reflux
Alkaline Hydrolysis: Add NaOH in alkaline conditions

My brain's gone blank haha maybe others could add? Hope this helps, sorry if I made any mistakes.
(edited 10 years ago)
Reply 1555
hey do we have to describe how to prepare single chiral isomers or can we just state the name of the methods such as chiral synthesis and using enzymes?
Original post by Chriswhjay
Can ANYONE please outline how to assemble a high resolution proton NMR or give any advice?! Im dreading seeing a 10 mark question and not getting the right shape! I can analyse it correctly and all, its just putting it together, it always goes wrong D;


This guy explains it really well:

http://www.youtube.com/watch?v=k6F__pysc74

But if you're just having trouble putting it all together maybe it's just a case of practising trial and error? Or it could be something in your technique of tackling the question which may make it difficult for you to determine a structure. After watching this guy teach it (and there's another video about combined techniques) I love doing those 10 markers, was so gutted that they didn't come up in jan!

EDIT: I've added some worksheets that have lots of proton and carbon NMR questions for anyone who wants to practice.
(edited 10 years ago)
Reply 1557
Original post by amsss
I've attached a list of all the conditions and reagents I've been using to revise, think almost everything is covered in there:smile:

ImageUploadedByStudent Room1371397356.786392.jpg

You can probably ignore the first one :smile:


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Nice, but is KCN/H+ stuff still in our spec?

BTW, question for anyone. Saw in an old paper; "Compound B is a saturated hydrocarbon and the NMR of compound B contains just one peak." The answer btw is that Compound B is an alkane, so how does an alkane only have one peak, wouldn't it have 2 chemical environments? C-CH2-C and C-CH3?
Did my first past paper and got 55/60 on Jan 2010, I'm hoping to race through another two tonight and the rest tomorrow and Tuesday night! Hopefully this A/A* is still capable :biggrin:
Reply 1559
I'm doing this paper. I much prefer this module in comparison with F325 in Jan and the past papers are relatively easy in comparison. Hoping for a very hard proton NMR question - it's very satisfying piecing together the unknown compound at the end of the paper.