Elimination of bromine from 2-bromobutane results in the formation of

The predominant product is 2-butene (a Saytzeffs products).

In this elimination reaction of alkyl halide major product is produced according to Saytzeff’s rule. This states that when two alkenes may be formed, then alkene which is most substituted one predominates. Therefore, predominantly (80%) 2-butene will be produced.