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    Hi,

    I've just got a couple of questions that I'm a bit stuck on.

    1. Is CH3(CH)2CH3 ethene? I'm a bit confused about what the bracket means and what ethene would be reduced to.

    For the question that I've attached. I think that propanone is reduced to propan-2-ol. I'm not sure how to work out what M is as I'm a bit confused about the difference between converts (I've never seen it in a chemistry context before) and reacts.

    Any help would be really appreciated.
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    (Original post by VioletPhillippo)
    Hi,

    I've just got a couple of questions that I'm a bit stuck on.

    1. Is CH3(CH)2CH3 ethene? I'm a bit confused about what the bracket means and what ethene would be reduced to.

    For the question that I've attached. I think that propanone is reduced to propan-2-ol. I'm not sure how to work out what M is as I'm a bit confused about the difference between converts (I've never seen it in a chemistry context before) and reacts.

    Any help would be really appreciated.
    1. ermm no...

    ethene is CH2=CH2

    prop-1-ene would be CH3CH=CH2

    what you have drawn is not feasible - draw and see it. it is much better than imagining in your head. if you can't see it, how can you do it better, unless you are really advanced.

    2. synthesis

    starting material is propanone - with 3 x C total, and also highly polar C=O which typically undergoes nucleophilic addition.

    hence step 1: the reduction converts the propanone into propan-2-ol (the secondary alcohol; oxidation of a secondary alcohol forms a ketone)

    step 2: the -OH is not as good a leaving group as -Cl or -Br. partly because, well, what bonds need to be broken? E(C-O) vs E(C-Cl) for example...you can also find out from Data Booklet which bond is weaker and hence easier to be broken.

    to be honest, you can turn R-OH into R-Br using red P and Br2 directly. I am a bit lost on what the question wants on the 3-stage instead.
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    CH3(CH)2CH3 is an unkind way of drawing but-2-ene.
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    (Original post by Pigster)
    CH3(CH)2CH3 is an unkind way of drawing but-2-ene.
    Thank you
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    (Original post by shengoc)
    1. ermm no...

    ethene is CH2=CH2

    prop-1-ene would be CH3CH=CH2

    what you have drawn is not feasible - draw and see it. it is much better than imagining in your head. if you can't see it, how can you do it better, unless you are really advanced.

    2. synthesis

    starting material is propanone - with 3 x C total, and also highly polar C=O which typically undergoes nucleophilic addition.

    hence step 1: the reduction converts the propanone into propan-2-ol (the secondary alcohol; oxidation of a secondary alcohol forms a ketone)

    step 2: the -OH is not as good a leaving group as -Cl or -Br. partly because, well, what bonds need to be broken? E(C-O) vs E(C-Cl) for example...you can also find out from Data Booklet which bond is weaker and hence easier to be broken.

    to be honest, you can turn R-OH into R-Br using red P and Br2 directly. I am a bit lost on what the question wants on the 3-stage instead.
    Thanks for your help, I thought about going from but-2-ene and adding Br2 but then you end up with too many bromines on the end product. I can't work out how to get to the end product in 2 steps either.
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    (Original post by VioletPhillippo)
    Thanks for your help, I thought about going from but-2-ene and adding Br2 but then you end up with too many bromines on the end product. I can't work out how to get to the end product in 2 steps either.
    Instead of doing an electrophilic addition mechanism using Br2, just use the same mechanism with HBr - which has the added advantage of having a permanent dipole, rather than having to induce one.
 
 
 
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