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Racemate question Watch

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    The question is this:

    "State whether the following preparations will produce a racemate or a single enantiomer:
    butan-2-ol from 2-bromobutane"

    I initially answered it racemate, but the answer is a single enantiomer.

    Now I understand how alcohols are formed from halogenoalkanes via nucleophilic substitution with a hydroxide ion.

    But 2-bromobutane is a chiral molecule. So, in the reaction, there will be a racemate of 2-bromobutane. The two enantiomers will react to produce the respective enantiomers of butan-2-ol, hence a racemate forms.
    Is my thinking wrong?

    I have googled and tried to do my own research, that only confused things further.
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    (Original post by RMNDK)
    The question is this:

    "State whether the following preparations will produce a racemate or a single enantiomer:iiik
    butan-2-ol from 2-bromobutane"

    I initially answered it racemate, but the answer is a single enantiomer.

    Now I understand how alochols are formed from halogenoalkanes via nucleophilic substitution with a hydroxide ion.

    But 2-bromobutane is a chiral molecule. So, in the reaction, there will be a racemate of 2-bromobutane. The two enantiomers will react to produce the respective enantiomers of butan-2-ol, hence a racemate forms.
    Is my thinking wrong?

    I have googled and tried to do my own research, that only confused things further.
    Is that the complete question? With info given I am siding with you.
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    The other issue, apart from us not knowing whether the reactant was a single enantiomer, is that 2-bromobutane might do both SN1 and SN2. The former would convert a single enantiomer to a racemic mixture.
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    (Original post by TeachChemistry)
    Is that the complete question? With info given I am siding with you.
    That is literally the complete question. There isn't any other information given apart from the post I made. So there is no indication of specifics of reaction conditions or the nature of reactants/products.
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    (Original post by Pigster)
    The other issue, apart from us not knowing whether the reactant was a single enantiomer, is that 2-bromobutane might do both SN1 and SN2. The former would convert a single enantiomer to a racemic mixture.
    Those terms you mentioned, SN1 and SN2, was what ended up confusing me when I decided to google this, so I'm presuming that's where the answer lies.
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    Essentially the difference is that in an SN2 reaction, the reaction proceeds in such a way as to preserve (actually invert) a chiral carbon. Secondary haloalkanes usually do SN2. IF the reactant was a single enantiomer (not stated in Q) AND IF the conditions were correct (again not stated) the reaction might be SN2 and the product would be a single enantiomer.

    In certain conditions, it might do SN1. In this case, there is an intermediate step which is trigonal planar. The attacking nucleophile can then attack from the top or the bottom (assuming the plane is horizontal). This means that the product will be a mixture of both enantiomers.
 
 
 
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