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    (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.
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    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?!
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    (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
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    (Original post by thers)
    My next question is: Name the molecule above [50]

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    :rolleyes:
    which structure above
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    what is transesterification ?
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    (Original post by k54g00)
    How can H2N-(CH2)4-NH2 be synthesised from Cl-(CH2)4-Cl??
    Excess NH3/Ethanol solvent and Reflux
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    (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?
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    (Original post by otrivine)
    which structure above
    The one I just asked about the chiral carbons. Was only joking lol.
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    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!!

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    (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
    Sometimes they give you a huge space and a few lines.
    But even then,mechanism will always give you the marks.
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    (Original post by thers)
    my next question is: Name the molecule above [50]

    Spoiler:
    Show
    :rolleyes:
    yusssss! I'm so heppy i got the answer right yayayayaya!
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    does metal carbonate only work with carboxylic acid in phenol?
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    (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 !!

    all the best!!

    speak tomorrow afternoon
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    (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
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    (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?
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    (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
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    (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 There might be bits missing, but I'll doubt they'll ask us to describe in words anyway.
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    (Original post by chiny94)
    does metal carbonate only work with carboxylic acid in phenol?
    Only with the COOH group, not with the CHO or OH or NH2 or C=O group.
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    (Original post by Varsh05)
    Sometimes they give you a huge space and a few lines.
    But even then,mechanism will always give you the marks.
    okay thanks very much
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    (Original post by chiny94)
    does metal carbonate only work with carboxylic acid in phenol?
    only carboxylic acids as phenols are not strong enough to reaction carbonates.
 
 
 
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