For 2-bromobutane treated with KOH in ethanol, which is the major elimination product and which is the minor product?

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Multiple Choice

For 2-bromobutane treated with KOH in ethanol, which is the major elimination product and which is the minor product?

The reaction follows E2 elimination where a base removes a β-hydrogen and a double bond forms. The more substituted alkene is favored (Zaitsev’s rule), so eliminating the hydrogen on the adjacent carbon that leads to a 2-butene is preferred over forming 1-butene. Between the two stereoisomers of 2-butene, the trans form is more stable than the cis form, so trans-2-butene is formed predominantly. The cis-2-butene is produced in smaller amounts, making it the minor product. Therefore, trans-2-butene is the major product and cis-2-butene is the minor product.

The reaction follows E2 elimination where a base removes a β-hydrogen and a double bond forms. The more substituted alkene is favored (Zaitsev’s rule), so eliminating the hydrogen on the adjacent carbon that leads to a 2-butene is preferred over forming 1-butene. Between the two stereoisomers of 2-butene, the trans form is more stable than the cis form, so trans-2-butene is formed predominantly. The cis-2-butene is produced in smaller amounts, making it the minor product. Therefore, trans-2-butene is the major product and cis-2-butene is the minor product.

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