Chemistry Synthesis Alkene Halogenoalkane and Alcohol

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universalcj
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#1
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Halogenoalkane + NaoH -> Alcohol ( heat under reflux )
right?

and also
Halogenoalkane + Alcoholic Basic Solution -> Alkene ( heat under reflux )

then can this Alcoholic Basic Solution be NaOH

then what' wrong with this

two exactly same reactants and the same condition
but different product?
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qwert7890
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(Original post by universalcj)
Halogenoalkane + NaoH -> Alcohol ( heat under reflux )
right?

and also
Halogenoalkane + Alcoholic Basic Solution -> Alkene ( heat under reflux )

then can this Alcoholic Basic Solution be NaOH

then what' wrong with this

two exactly same reactants and the same condition
but different product?
You are missing the key word there - it's supposed to be alcoholic basic solution, not a simple basic solution. This means the base (NaOH) must be dissolved in an alcohol (the most popular solvent being ethanol in these situations).

Do note that not every compound with -OH is an alcohol. For ex. Mg(OH)2 is not classified as an alcohol, and by this logic neither is NaOH an alcohol. An alcohol (as far as I know) is defined by an -OH group attached to an organic compound (i.e. a carbon atom).
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universalcj
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(Original post by qwert7890)
You are missing the key word there - it's supposed to be alcoholic basic solution, not a simple basic solution. This means the base (NaOH) must be dissolved in an alcohol (the most popular solvent being ethanol in these situations).

Do note that not every compound with -OH is an alcohol. For ex. Mg(OH)2 is not classified as an alcohol, and by this logic neither is NaOH an alcohol. An alcohol (as far as I know) is defined by an -OH group attached to an organic compound (i.e. a carbon atom).
so NaOH dissolved in Alcohol???? is it fine?
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BDavies1
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NaOH (dissolved in water)+ haloalkane --> alcohol (nucleophilic subs) (OH- behaves as a nucleophile)
But NaOH (dissolved in H2O) + haloalkane --> alkene + HBr (elimination) (OH- behaves as a base)
Q's always on this always come up eg.
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qwert7890
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(Original post by BDavies1)
NaOH (dissolved in water)+ haloalkane --> alcohol (nucleophilic subs) (OH- behaves as a nucleophile)
But NaOH (dissolved in H2O) + haloalkane --> alkene + HBr (elimination) (OH- behaves as a base)
Q's always on this always come up eg.
There's no difference in the two reactions you've described...
the one difference (afaik) is that in the second reaction, the NaOH is dissolved in alcohol (ex. ethanol).
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BDavies1
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(Original post by qwert7890)
There's no difference in the two reactions you've described...
the one difference (afaik) is that in the second reaction, the NaOH is dissolved in alcohol (ex. ethanol).
You get two different products (an alcohol in the first reaction when the OH- behaves as a base) and an alkene in the second (where the OH- behaves as base). Two different reactions.
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qwert7890
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(Original post by BDavies1)
You get two different products (an alcohol in the first reaction when the OH- behaves as a base) and an alkene in the second (where the OH- behaves as base). Two different reactions.
I meant a difference in the reaction conditions. The second one should be NaOH dissolved in ethanol, not water.
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