CH3O-, is this strong base?

joonkimdds

Senior Member
10+ Year Member
7+ Year Member
Jun 30, 2005
2,780
2
  1. Pre-Dental
    Hi guys.

    I believe that strong base + alcohol causes elimination.

    Destroyer #147 in orgo has primary halide + CH3O- + alcohol and it does substitution reaction. I believe this is william ether synthesis which is SN2.

    Destroyer #31 in orgo has tertiary halide + CH3OH + alcohol and it does substitution reaction.

    After seeing problems like this, I think CH3O- is same as CH3OH and both of them might be weak base since they cause substitution instead of elimination

    But Destroyer #143 shows that C2H5O- with alcohol causes elimination reaction.


    Does this mean CH3O- is weak base but C2H5O- is a strong base?
     

    UCB05

    Full Member
    Jun 14, 2009
    800
    3
    1. Pre-Dental
      Williamson Ether synthesis happens when an organometallic compound (CH3ONa) reacts with a primary,sometimes secondary, halide by SN2. This is a special case, and you have to have an organometal and alkyl halide for it to happen.

      Tertiary halides undergo SN1 substitution as the major product, with some elimination as minor product under the right conditions.

      -OH is not a good leaving group.

      The conjugate base of weak acids are strong bases. MeO- and EtO- are strong bases. MeOH and EtOH are weak nucleophiles.
       
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