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JEE Main levelOne or more correct optionsDifficulty 2 of 3o4230

The halide shown is treated with sodium ethoxide in ethanol in one experiment and with potassium tert-butoxide in tert-butanol in another. Select all correct statements.

  1. AWith sodium ethoxide the major alkene is trans-but-2-ene.
  2. BReplacing ethoxide by tert-butoxide increases the fraction of but-1-ene in the product mixture.
  3. Ccis-But-2-ene is the major alkene with sodium ethoxide.
  4. DThe halide has five beta-hydrogens.

Answer: A, B, D

The compound is 2-bromobutane, with 3 H on C-1 and 2 H on C-3, so five beta-hydrogens. Ethoxide follows Saytzeff and the trans isomer is more stable and favoured over cis. The bulkier tert-butoxide removes the more accessible methyl hydrogen more often, raising the but-1-ene content, but cis-but-2-ene is not the major product.
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