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    Page 63 of the GCSE Chemistry Specification says...

    "For example: glycine is H2NCH2COOH and polymerises to producethe polypeptide
    (-HNCH2COO-)n
    and n H2O"

    However, drawing out the polymerisation, this doesn't seem right - the carboxyl group should lose the whole -OH, not just the -H, otherwise it wouldn't be a peptide bond, and there would be no oxygen lost so H2O would not be formed. The polymer should be (-HNCH2CO-)n.

    Have I made some grave error, or is this a typo in the spec?
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    youve made a grave error :P,
    The Carboxylic group and the Amine group produce the water, not two carboxylic acid groups.
    Hope this helps haha Name:  image-a5fede63-c75e-455d-9d87-28c960b0b7b2402024947-compressed.jpg.jpeg
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    (Original post by Najrul Islam)
    youve made a grave error :P,
    The Carboxylic group and the Amine group produce the water, not two carboxylic acid groups.
    Hope this helps haha Name:  image-a5fede63-c75e-455d-9d87-28c960b0b7b2402024947-compressed.jpg.jpeg
Views: 24
Size:  23.6 KB
    Thanks for taking the time to draw this out, however I don't think you've read my question properly.I'm not talking about the formation of a dipeptide, as you've drawn, but the polymerisation into a polypeptide, where there will be a repeating unit.

    According to the specification, this repeating unit will be (-HNCH2COO-), however this doesn't seem right and I think it should be (-HNCH2CO-).

    In this image from wikipedia:



    ... we can see that the repeating unit is how I described it, (-HNCH2CO-), as the full -OH group from the carboxyl group is lost, so it cannot be -COO. So it looks like AQA have just made a typo in their spec :P
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    haha my bad, yes you are right
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    I knew there was a mistake! Why have AQA not corrected this yet? Or are we missing something? I spoke to my chemistry teacher a while ago and he also thinks it is a mistake.
 
 
 

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