To determine the type of reaction that occurs with an alkyl hailide you
must first analyze the alkyl halide. More specifically, you must determine
the accessibility of the alkyl halide for a potential backside attack if
considering the SN2 mechanism. Alkyl groups hinder SN2
reactions in that they provide steric hindrance that limits the backside
attack by a nucleophile. Methyl halides, like the one shown above, will
react readily and quickly in the SN2 reaction because of the
total accessibility of the backside of the carbon at which the attack of
a nucleophile will occur. Please notice that the picture on the left is
the side view of the molecule, and the picture on the right is rotated
ninety degrees. This is how the nucleophile would approach this molecule.
To determine the type of reaction that occurs with an alkyl hailide you
must first analyze the alkyl halide. More specifically, you must determine
the accessibility of the alkyl halide for a potential backside attack if
considering the SN2 mechanism. Alkyl groups hinder SN2
reactions in that they provide steric hindrance that limits the backside
attack by a nucleophile. Primay alkyl halides, like the ethyl derivative
shown above, will react in an SN2 mechanism but not as readily
or quickly as the methyl alkyl halide. The additional methyl group slightly
limits the accessibility of the carbon at which the backside attack of
a nucleophile will occur. Please notice that the picture on the left is
the side view of the molecule, and the picture on the right is rotated.
This is how the nucleophile would approach this molecule.
To determine the type of reaction that occurs with an alkyl hailide you
must first analyze the alkyl halide. More specifically, you must determine
the accessibility of the alkyl halide for a potential backside attack if
considering the SN2 mechanism. Alkyl groups hinder SN2
reactions in that they provide steric hindrance that limits the backside
attack by a nucleophile. Secondary alkyl halides, like the isopropyl derivative
above, will react in an SN2 mechanism but not as readily or
quickly as the methyl alkyl halide or a primary alkyl halide. The additional
methyl groups limit the accessibility of the carbon at which the backside
attack of a nucleophile will occur. Please notice that the picture on the
left is the side view of the molecule, and the picture on the right is
rotated. This is how the nucleophile would approach this molecule.
To determine the type of reaction that occurs with an alkyl hailide you
must first analyze the alkyl halide. More specifically, you must determine
the accessibility of the alkyl halide for a potential backside attack if
considering the SN2 mechanism. Alkyl groups hinder SN2
reactions in that they provide steric hindrance that limits the backside
attack by a nucleophile. Neopentyl alkyl halides, like the one shown above,
react only very slowly via an SN2 mechanism. The numerous methyl
groups provide steric hindrance and thus make the carbon relatively inaccessible
to nucleophlic backside attack. Please notice that the picture on the left
is the side view of the molecule, and the picture on the right is rotated.
This is how the nucleophile would approach this molecule.
To determine the type of reaction that occurs with an alkyl hailide you
must first analyze the alkyl halide. More specifically, you must determine
the accessibility of the alkyl halide for a potential backside attack if
considering the SN2 mechanism. Alkyl groups hinder SN2
reactions in that they provide steric hindrance that limits the backside
attack by a nucleophile. Tertiary alkyl halides, like the one shown above,
will react only exceedingly slowly or not at all via an SN2
mechanism. The numerous methyl groups provide steric hindrance and makes
the carbon almost entirely inaccessible to nucleophlic backside attack.
Please notice that the picture on the left is the side view of the molecule,
and the picture on the right is rotated. This is how the nucleophile would
approach this molecule.
For further enlightenment,
go to the Organic
Chemistry Movies page. There are animated movies of E2 and SN2 reactions.
Just point and click!