The reaction of propene with HOCl(Cl2+H2O) proceeds through the intermediate:

  • CH3−CH+−CH2−Cl

  • CH3−CH(OH)−C+H2

  • CH3−CHCl−C+H2

  • CH3−CHCl−C+H2


A.

CH3−CH+−CH2−Cl

CH subscript 3 space minus CH equals CH subscript 2 space rightwards arrow from left parenthesis electrophilic space addition right parenthesis to straight H straight O with straight delta minus on top minus straight C with straight delta plus on top straight l of space stack CH subscript 3 space minus straight C with plus on top straight H space minus CH subscript 2 minus Cl with left parenthesis intermediate right parenthesis below
rightwards arrow with straight O with minus on top straight H on top space CH subscript 3 minus CH left parenthesis OH right parenthesis minus CH subscript 2 minus Cl
CH subscript 3 space minus CH equals CH subscript 2 space rightwards arrow from left parenthesis electrophilic space addition right parenthesis to straight H straight O with straight delta minus on top minus straight C with straight delta plus on top straight l of space stack CH subscript 3 space minus straight C with plus on top straight H space minus CH subscript 2 minus Cl with left parenthesis intermediate right parenthesis below
rightwards arrow with straight O with minus on top straight H on top space CH subscript 3 minus CH left parenthesis OH right parenthesis minus CH subscript 2 minus Cl
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The product of the reaction given below is:


A.

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In SN2 reactions, the correct order of reactivity for the following compounds CH3Cl, CH3CH2Cl, (CH3)2CHCl and (CH3)3CCl is

  • CH3Cl > (CH3)2CHCl >CH3CH2Cl > (CH3)3CCl

  • CH3Cl > CH3CH2Cl > (CH3)2CHCl >(CH3)3CCl

  • CH3CH2Cl > CH3Cl >(CH3)2CHCl >(CH3)3CCl

  • CH3CH2Cl > CH3Cl >(CH3)2CHCl >(CH3)3CCl


B.

CH3Cl > CH3CH2Cl > (CH3)2CHCl >(CH3)3CCl

Rate space of space straight S subscript straight N 2 space proportional to fraction numerator 1 over denominator Steric space crowding space of space apostrophe straight C apostrophe end fraction
As steric hindrance (crowding) increases, the rate of SN2 reaction decreases.
The order of reactivity towards SN2 reaction for alkyl halides is 
Primary halides > Secondary halides >Tertiary halides
Rate space of space straight S subscript straight N 2 space proportional to fraction numerator 1 over denominator Steric space crowding space of space apostrophe straight C apostrophe end fraction
As steric hindrance (crowding) increases, the rate of SN2 reaction decreases.
The order of reactivity towards SN2 reaction for alkyl halides is 
Primary halides > Secondary halides >Tertiary halides
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: Answer the following: 

(i) Haloalkanes easily dissolve in organic solvents, why? 

(ii) What is known as a racemic mixture? Give an example. 

(iii) Of the two Bromo derivatives, C6H5CH(CH3)Br and C6H5CH(C6H5)Br, which one is more reactive in Sn1 substitution reaction and why? 


i) Haloalkanes can easily dissolve in organic solvents of low polarity because the new forces of attraction set up between haloalkanes and the solvent molecules are of same strength as the forces of attraction being broken. 

(ii) A mixture of equal amounts of two enantiomers is known as racemic mixture.  For example: When a 3° halide undergoes substitution with KOH, the reaction proceeds through SN 1 mechanism forming the racemic mixture in which one of the products has the same configuration as a reactant, while the other product has an inverted configuration. 

 

(iii) In SN1 reaction mechanism leads through the carbocation pathway.

 

 

 

More stable the carbocation, more reactive will be substrate .the carbocation formed by two compounds are as follows:

 Compound (C6H5)2CHBr = carbocation (C6H5)2CH+

Compound C6H5CH(CH3)Br=carbocation C6H5(CH3)CH+

Out of these two carbocations (C6H5)2CH+ is more stable than C6H5(CH3)CH+ because the carbocation(C6H5)2CH+  is resonance stabilised by two benzene rings .therefore (C6H5)2CHBr is more reactive than  C6H5CH(CH3)Br. Resonance stabilisation of carbocation with one benzene ring is shown :

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The synthesis of alkyl fluorides is best accomplished by

  • free radical fluorination

  • Sandmeyer's reaction

  • Finkelstein reaction

  • Finkelstein reaction


D.

Finkelstein reaction

Alkyl fluorides can be prepared by the action of mercurous fluorides or antimony trifluoride (inoragnic fluorides) on corresponding alkyl halide.

This reaction is known as Swarts reaction

CH3Br + AgF → CH3F + AgBr
But, when the action of NaI/acetone takes place on alkyl chloride or bromide alkyl iodide forms. This reaction is called 'Finkelstein reaction.
straight C subscript 2 straight H subscript 5 Cl space rightwards arrow from acetone to NaI of straight C subscript 2 straight H subscript 5 straight I space plus space NaCl
Free radical fluoridation is a highly explosive reaction. So not preferred for the preparation of fluoride.

Alkyl fluorides can be prepared by the action of mercurous fluorides or antimony trifluoride (inoragnic fluorides) on corresponding alkyl halide.

This reaction is known as Swarts reaction

CH3Br + AgF → CH3F + AgBr
But, when the action of NaI/acetone takes place on alkyl chloride or bromide alkyl iodide forms. This reaction is called 'Finkelstein reaction.
straight C subscript 2 straight H subscript 5 Cl space rightwards arrow from acetone to NaI of straight C subscript 2 straight H subscript 5 straight I space plus space NaCl
Free radical fluoridation is a highly explosive reaction. So not preferred for the preparation of fluoride.

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