The correct sequence ofsteps involved in the mechanism of Canniza

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

51.

The letter 'D' in D-glucose signifies

  • configuration at all chiral carbons

  • dextrorotatory

  • that it is a monosaccharide

  • configuration at a particular chiral carbon


52.

Reaction of methyl bromide with aqueous sodium hydroxide involves

  • racemisation

  • SN 1 mechanism

  • retention of configuration

  • SN 2 mechanism


53.

In alkaline medium, alanine exists predominantly as

  • anion

  • Zwitter ion

  • cation

  • Covalent form


54.

Benzaldehyde and acetone can be best distinguished using

  • Fehling's solution

  • Sodium hydroxide solution

  • 2, 4-DNP

  • Tollen's reagent


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55.

Phenol X forms a tribromo derivative, 'X' is

  • bromine in benzene

  • bromine in water

  • potassium bromide solution

  • bromine in carbon tetrachloride at 0°C


56.

One mole of an organic compound A with the formula C3H8O reacts completely With two moles of HI to form X and Y. When Y is boiled with aqueous alkali it forms Z. Z answers the iodoform test. The compound A is

  • propan-2-ol

  • propan-1-ol

  • ethoxyethane

  • methoxyethane


57.

CH3CH2Br aq KOH CH3CH2OH KMnO4/H+B NH3 C alkaliBr2 D, 'D' is

  • CH2Br

  • CH3CONH2

  • CH3NH2

  • CHBr3


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58.

The correct sequence ofsteps involved in the mechanism of Cannizaro's reaction is

  • nucleophilic attack, transfer of H- and transfer of H+

  • transfer of H-, transfer of H+ and nucleophilic attack

  • transfer if H+, nucleophilic attack and transfer of H-

  • electrophilic attack by OH-, transfer of H+ and transfer of H-


A.

nucleophilic attack, transfer of H- and transfer of H+

The Cannizaro reaction is as 

HCHO + HCHO KOH(con.) CH3OH methyl alcohol+ HCOOK+acetic acid

The mechanism of Cannizaro reaction is as
Step Ist : Attack of nucleophile OH- to the carbonyl carbon

Step Ind : The transfer of hydride ion from anion (I) to second molecule of aldehyde and finally rapid transfer of proton takes place.


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59.

The IUPAC name of 

  • 2-methyl-3-bromohexanal

  • 3-bromo-2-methylbutanal

  • 2-methyl-3-bromobutanal

  • 3-bromo-2-methylpentanal


60.

Which one of the following forms propane nitrile as the major product?

  • Ethyl bromide + alcoholic KCN

  • Propyl bromide + alcoholic KCN

  • Propyl bromide + alcoholic AgCN

  • Ethyl bromide + alcoholic AgCN


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