The ease of dehydrohalogenation of alkyl halide with alcohol

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 Multiple Choice QuestionsMultiple Choice Questions

781.

Assertion : Trans-2-butene on reaction with Br2 gives meso-2,3-dibromobutane.

Reason : The reaction involves syn -addition of bromine.

  • If both assertion and reason are true and the reason is the correct explanation of the assertion.

  • If both assertion and reason are true and the reason is not the correct explanation of the assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


782.

In a mixture, two enantiomers are found to be present in 85% and 15% respectively. The enantiomeric excess (ee) is

  • 85%

  • 15%

  • 70%

  • 60%


783.

The IUPAC name of the compound having the formula CCl3CH2CHO is

  • 2, 2, 2-trichloropropanal

  • 1,1, 1-trichloropropanal

  • 3, 3, 3-trichloropropanal

  • 1, 2, 1-dichloromethanal


784.

Best reagent for nuclear iodination of aromatic compounds is

  • KI/ CH3COCH3

  • I2/CH3CN

  • KI/ CH3COOH

  • I2 / HNO3


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785.

Identify the correct method for the synthesis of the compound shown below from the following alternatives.


786.

Which one of the following methods are used to prepare Me3COEt with good yield?

  • Mixing EtONa with Me2CCl

  • Mixing Me2CONa with EtCl

  • Heating a mixture of (1:1) EtOH and Me2COH in the presence of conc. H2SO4

  • Treatment of Me3COH with EtMgI


787.

Under identical conditions, the SN1 reaction will occur most efficiently with:

  • tert-butyl chloride

  • 1-chlorobutane

  • 2-methyl-1-chloropropane

  • 2-chlorobutane


788.

Identify the method by which Me3CCO2H can be prepared:

  • Treating 1 mole of MeCOMe with 2 moles of MeMgl

  • Treating 1 mole of MeCO3Me with 3 moles of MeMgI

  • Treating 1 mole of MeCHO with 3 moles of MeMgl

  • Treating 1 mole of dry ice with 1 mol of MeCMgI


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789.

The correct statement regarding the following compounds is

  • all three compounds are chiral

  • only I and II are chiral

  • I and III are diastereomers

  • only I and III are chiral


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790.

The ease of dehydrohalogenation of alkyl halide with alcoholic KOH is:

  • 3° < 2° < 1°

  • 3° > 2° > 1 °

  • 3° < 2° > 1°

  • 3° > 2° < 1 °


B.

3° > 2° > 1 °

According to Saytzeff rule, any alkyl halide that gives a more highly substituted (more stable) alkene undergoes dehydrohalogenation faster than the one which gives a less highly substituted (less stable) alkene. Thus, the ease of dehydrohalogenation of different alkyl halides having the· same halogen decreases in the order,

tertiary (3°) > secondary (2°) > primary (1°).


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