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Why are organic elimination reactions known as beta eliminations? Why don't we call them alpha eliminations?

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  • $\begingroup$ Take 2-bromobutane as an example. The C2 hydrogen is an alpha carbon while the hydrogens are referred to as beta. C4-H's are gamma. It is a generic terminology that fits all cases regardless of the numbering in the compound. There are alpha and beta eliminations. $\endgroup$ – user55119 Nov 26 '17 at 18:25
  • $\begingroup$ Addition: ...while the C1 and C3 hydrogens are referred to as beta. $\endgroup$ – user55119 Nov 26 '17 at 18:36
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In an elimination reaction we typically have a leaving group (denoted by "X" in the figure below), The carbon that the leaving group is attached to is referred to as the "alpha" carbon. If a hydrogen is removed from the "beta" carbon, then we have formed an olefin and the reaction is called a beta elimination.

The alpha and beta carbons in an elimination reaction

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Sometimes an alpha hydrogen can be removed. In this case both the hydrogen and leaving group were attached to the same carbon and a carbene is formed.

alpha elimination

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