Turn on thread page Beta

POST-EXAM CHAT: OCR Chemistry- Rings, Polymers and Analysis - F324 thread watch

    Offline

    0
    ReputationRep:
    Last question sucked!!
    I ended up making up some random formulas..
    and also, what did people get for the other observation of the bromination of phenol?
    Offline

    13
    ReputationRep:
    Guys,

    I put for reaction part C that chloroethane will react with the NH part of the paracetamol to form a bond, and drew the paracetamol with the N and an ethyl group coming off it. For the reagent I put chloroethane. Is that correct?

    Also, the question about that sugar, and the bit where it said it was heated with potassium dichromate, was I right in putting 3[O]? because the aldehyde group would be oxidised once and the hydroxyl group on the other side of the molecule would be oxidized twice to get it to carboxylic acid. Now tht i think about it, i dunno if it mentioned if it was refluxed r condensed off
    Offline

    13
    ReputationRep:
    (Original post by sidrah)
    Last question sucked!!
    I ended up making up some random formulas..
    and also, what did people get for the other observation of the bromination of phenol?
    A white precipitate was formed. there's a pic in the book somewhere
    Offline

    0
    ReputationRep:
    (Original post by AnthonyShock)
    A white precipitate was formed. there's a pic in the book somewhere
    ohhh... damn.. I just remembered we did that in class :/
    And I sniffed it really stupidly.. never going to repeat that mistake.
    Oh well, A* out of the question anyway.. I'll settle for an A and just work harder in June.
    Offline

    0
    ReputationRep:
    crap i wrote RF value instead of Rf...
    Offline

    2
    ReputationRep:
    (Original post by AnthonyShock)
    A white precipitate was formed. there's a pic in the book somewhere
    Thank god.

    I remember reading in the book that something decolourises and a white gas is given of and could decide.
    Offline

    0
    ReputationRep:
    Could someone please tell me if any of these are right for the last question =(

    A- NaOH
    B- KOH
    c - Bromine
    Offline

    4
    ReputationRep:
    (Original post by AnthonyShock)
    A white precipitate was formed. there's a pic in the book somewhere
    Would you get away with saying a gas is given off?
    Offline

    0
    ReputationRep:
    (Original post by JordanCarroll)
    without a shadow of a doubt
    (CH3)2CHCOOCH3
    is that the answer please say YES!!!!! thats wat i wrote!!
    Offline

    0
    ReputationRep:
    (Original post by ghazalkhan)
    is that the answer please say YES!!!!! thats wat i wrote!!
    According to most people in this thread yes :yep:
    Offline

    11
    ReputationRep:
    (Original post by Pedus)
    Would you get away with saying a gas is given off?
    Probably. It's as much an observation as seeing a precipitate being formed, or seeing a solid disolve, etc. Should be ok, but they were definitely looking for white precipitate.

    (Original post by BHAM!)
    crap i wrote RF value instead of Rf...
    Something tells me you'll be ok.
    Offline

    0
    ReputationRep:
    For the last question would it have been alrite to put:
    A - Na, because will form carboxyl and phenoxide ion
    B - NaBH4, will reduce the carvoxylic to benzaldehyde
    C - Br2, will react with benzene ring because of phenol activation???
    Offline

    1
    ReputationRep:
    (Original post by meiming8)
    Yeah, I put that as well...is this the one where you get a dicarboxylic acid, and then you draw the mechanism? The mechanism was really hard to do for both sides...I don't know if I did it right, it seemed like an odd question :confused:
    the mechanism was nucleophillic addition surely, it was for the reduction of the aldehyde to alcohol?

    am i right guys? x
    Offline

    0
    ReputationRep:
    (Original post by BHAM!)
    According to most people in this thread yes :yep:
    oh thankxxxxxx ! well at least i got 5marks
    Offline

    0
    ReputationRep:
    (Original post by The_wise)
    the mechanism was nucleophillic addition surely, it was for the reduction of the aldehyde to alcohol?

    am i right guys? x
    it didnt ask for wat type of reaction it was:confused: well i didnt see that??/
    Offline

    17
    ReputationRep:
    (Original post by The_wise)
    the mechanism was nucleophillic addition surely, it was for the reduction of the aldehyde to alcohol?

    am i right guys? x
    Yeah, the NaBH4 provides the hydride ion H-. It is nucleophilic addition. The pi-bond electrons move into the oxygen, which is then protonated by the water.
    Offline

    17
    ReputationRep:
    (Original post by ghazalkhan)
    it didnt ask for wat type of reaction it was:confused: well i didnt see that??/
    No, you had to show the mechanism.
    Offline

    0
    ReputationRep:
    (Original post by dave008)
    For the last question would it have been alrite to put:
    A - Na, because will form carboxyl and phenoxide ion
    B - NaBH4, will reduce the carvoxylic to benzaldehyde
    C - Br2, will react with benzene ring because of phenol activation???
    I got A and C similarly but for B i wrote KOH (just thought phenol would'nt react with it because its too weak) I just want someone to tell me I'll get atleast 2 marks!
    Offline

    0
    ReputationRep:
    (Original post by ghazalkhan)
    oh thankxxxxxx ! well at least i got 5marks
    Was that the bottom right in the corner? I don't remember which one i chose just that it wasn't the top right.
    Offline

    11
    ReputationRep:
    (Original post by BHAM!)
    I got A and C similarly but for B i wrote KOH (just thought phenol would'nt react with it because its too weak) I just want someone to tell me I'll get atleast 2 marks!
    A + C should be ok, but NaBH4 still can't reduce a -COOH group by itself. Like I said before, they might ALLOW it due to confusing it with LiAlH4, but it's still not technically true, but then again, if you put LiAlH4 for anything but the first one, it wouldn't be right, since it would reduce bonds found in both of the compounds.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 2, 2010
The home of Results and Clearing

2,915

people online now

1,567,000

students helped last year

University open days

  1. London Metropolitan University
    Undergraduate Open Day Undergraduate
    Sat, 18 Aug '18
  2. Edge Hill University
    All Faculties Undergraduate
    Sat, 18 Aug '18
  3. Bournemouth University
    Clearing Open Day Undergraduate
    Sat, 18 Aug '18
Poll
A-level students - how do you feel about your results?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.