Organic Chem

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I want to ask,

HBr+alkene

They ask Type of reaction.

Why hydrohalogenation is wrong?

Electrophilic addition is right?

Why is that Bromination?

In Singapore, teachers said and Cambridge paper said

Type of rxn is the general name.

Type of mechanism is mechanism.

Update:

Forget the above Qn.

MAY I know:

Is it truth that

SN1: 3' and 2' RX

SN2:1' and 2' RX?

The teacher say must be chiral C for SN rxns.

2 Answers

Rating
  • LOK
    Lv 5
    8 years ago
    Best Answer

    Hydrogenation belongs to Electrophilic addition

    2012-06-01 11:40:12 補充:

    Personally, I don't consider hydrogenation/hydrohalogenation '' a type of reaction''.

    Being ''a type of reaction'', it should be general enough, which makes certain reactions contain features of that reaction.

    2012-06-01 11:45:39 補充:

    i.e. hydrohalogenation is only a specific reaction that belongs to Electrophilic addition (a type of reaction). all the EA reactions have the similiar routes (mechanisms) and have electrophiles. But hydrohalogenation does not have some General features that can be used to distinguish a reaction

    2012-06-02 22:17:11 補充:

    Is it truth that

    SN1: 3' and 2' RX

    SN2:1' and 2' RX?

    >>Unnecessary. Whether a reaction will undergo by SN1/2 depends on numerous factors. There is no fixed formula to deduce whether a reaction is Sn1/2. However, in most cases, 3' RX is SN1 while 1' RX is SN2.

    As for 2' RX, it really depends on other factors. The type of nucleophilic substitution reaction of different 2' RX varies greatly. (It depends on the strength of nucleophiles, leaving group, solvent, RX, temperature, steric effect...)

    Please note that even a 1' RX will undergo both SN1 and SN2, but SN1 may have a larger ratio. The same is true for 3' RX.

    Please note that 3' RX can easily undergo an elimination reaction instead of a SN1 reaction because of its strong steric effect.

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    The teacher say must be chiral C for SN rxns.

    Actually, I don't quite understand what you are saying.

    If you are asking must there be a chiral C centre after a SN reaction, I would say this is absolutely WRONG. To be a chiral C centre, a C must be affixed directly with 4 DIFFERENT groups. But even a C atom is not affixed with 4 different groups, it can still undergo SN reactions. (CH4, C(CH3)3 for example)

    If you are asking must there be a chiral C centre after a SN3 reaction, I would also say this is absolutely WRONG. As whether a compound has a chiral C centre has NOTHING to do with the route of its synthesis. As I said before, it depends on the groups that the central C is affixed to.

  • 8 years ago

    Hydrohalogenation may not be wrong, but bromination must be incorrect!

    Bromination refers to treatment of a compound with bromine

    In this case propene is treated with hydrogen bromide

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