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प्रश्न
Distinguish between SN1 and SN2 mechanism of substitution reaction.
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उत्तर
| Factor | SN1 | SN2 |
| Kinetics | 1st order | 2nd order |
| Molecularity | Unimolecular | Bimolecular |
| Number of steps | Two steps | One step |
| Bond making and bond breaking | First the bond in the reactant breaks and then a new bond in the product is formed. | Simultaneous |
| Transition state | Two steps, two transition states | One step, one transition state |
| Direction of attack of nucleophile | Backside attack and frontside attack | Only back side attack |
| Stereochemistry | Racemisation (If the substrate is optically active) | Inversion of configuration (If the substrate is optically active) |
| Type of substrate | Mainly 3° substrates | Mainly 1° substrate |
| Polarity of solvent | Polar protic solvent favorable | Aprotic (non-polar) or solvent with low polarity favourable |
| Intermediate | Intermediate involved | No intermediate |
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संबंधित प्रश्न
from the following pair would undergo SN2 faster from the other?
a. CH3CH2CH2I b. CH3CH2CH2Cl
Complete the following reaction giving major product.
\[\begin{array}{cc}\ce{CH3\phantom{................}}\\
|\phantom{...................}\\
\ce{CH3 - C - CH2 - Cl ->[Na/dry ether] A}\\
|\phantom{...................}\\
\ce{CH3\phantom{................}}
\end{array}\]
Give reasons:
Haloarenes are less reactive than haloalkanes.
Convert the following:
Propene to propan-1-ol
Convert the following:
Benzyl alcohol to benzyl cyanide
Convert the following:
Ethanol to propane nitrile
Convert the following:
tert-Butyl bromide to isobutyl bromide
HCl is added to a hydrocarbon ‘A’ \[\ce{(C4H8)}\] to give a compound ‘B’ which on hydrolysis with aqueous alkali forms tertiary alcohol ‘C’ \[\ce{(C4H10O)}\]. Identify ‘A’ ,‘B’ and ‘C’.
Complete the following reaction sequence by writing the structural formulae of the organic compound 'A', 'B' and 'C'.
\[\ce{Isopropyl alcohol ->[\triangle][PBr3] A ->[][NH3 excess] B}\]
Observe the following and answer the question given below.
Can it react by SN1 mechanism? Justify your answer.
Which of the following is least reactive towards SN1 reactions?
Ethyl bromide undergoes the following reaction:
\[\ce{\underset{Ethyl bromide}{C2H5Br} + \underset{(aq.)}{KOH} ->[\Delta] \underset{Ethyl alcohol}{C2H5OH} + KBr}\]
Which of the following is a WRONG statement?
Which of the following is least reactive towards nucleophilic addition?
What type of hybridisation is present in carbocation formed during the alkaline hydrolysis of 1- bromo-1- phenyl ethane?
Which of the following carbocation is the most stable?
When C2H5Br is treated with excess of alc. NH3, the major product obtained is ____________.
The SN2 reaction of a compound containing an asymmetric carbon atom always gives ____________.
Identify 'B' in the following reaction.
\[\ce{2-Bromobutane ->[KOH alc.][\Delta] A ->[HI] B}\]
The compound that reacts the fastest with sodium methoxide is ______.
Complete the following reaction giving major products.
\[\begin{array}{cc}
\ce{CH3}\phantom{.......}\\
|\phantom{.........}\\
\ce{CH3 - c - CH2 - Cl ->[Na/dry ether]}\\
|\phantom{.........}\\
\ce{CH3}\phantom{.......}
\end{array}\]
Complete the following reaction giving a major product.
\[\begin{array}{cc}
\ce{CH3}\phantom{.................}\\
|\phantom{...................}\\
\ce{CH3 - C - CH2 - Cl->[Na/dry ether]A}\\
|\phantom{..................}\\
\ce{CH3}\phantom{................}
\end{array}\]
Define and explain the SN1 mechanism with a suitable example.
Complete the following reaction giving major product.
\[\begin{array}{cc}
\ce{CH3}\phantom{................}\\
|\phantom{...................}\\
\ce{CH3 - C - CH2 - Cl->[Na/ dry ether]A}\\
|\phantom{...................}\\
\ce{CH3}\phantom{................}\\
\end{array}\]
Which of the following pair of compounds on heating gives butanenitrile?
Which among the following is NOT benzylic halide?
Which of the following reagent is used for conversion of alkyl halide into nitrile?
