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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
Complete the following reaction giving major product.
\[\begin{array}{cc}\ce{CH3\phantom{................}}\\
|\phantom{...................}\\
\ce{CH3 - C - CH2 - Cl ->[Na/dry ether] A}\\
|\phantom{...................}\\
\ce{CH3\phantom{................}}
\end{array}\]
Arrange the following in the increasing order of boiling points.
- 1-Bromopropane
- 2- Bromopropane
- 1- Bromobutane
- 1-Bromo-2-methylpropane
Complete the following reaction sequence by writing the structural formulae of the organic compound 'A', 'B' and 'C'.
\[\ce{2-Bromobutane->[Alc.KOH]A->[][Br2]B->[][NaNH2]C}\]
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.
Comment on the bond length of C–X bond in it.
The following will react faster by SN1 mechanism
Major product of the following reaction is _______________
\[\ce{CH3-CH2-Mg-Br + NH3 ->?}\]
Explain. Aryl halides are less reactive than alkyl halides towards nucleophilic substitution reactions.
What is dehydrohalogenation? State the rule for the formation of the preferred product of dehydrohalogenation.
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?
Dehydrohalogenation of an alkyl halide is ____________.
The following mechanism has been proposed for the reaction of NO2 with F2 to form NO2F:
\[\ce{NO2_{(g)} + F2_{(g)} -> NO2F_{(g)} + F_{(g)} (slow)}\]
\[\ce{F_{(g)} + NO2_{(g)} -> NO2F_{(g)} (fast)}\]
The order of the reaction with respect to NO2(g)
What type of hybridisation is present in carbocation formed during the alkaline hydrolysis of 1- bromo-1- phenyl ethane?
\[\ce{C6H5CH2Cl + KCN(alc) -> X + Y}\]
Compounds X and Y are ____________.
When C2H5Br is treated with excess of alc. NH3, the major product obtained is ____________.
Identify major product 'B' in the following reaction.
\[\ce{But-1-ene ->[HBr][Peroxide] A ->[AgCN][\Delta] B}\]
What is the major product obtained in the sulphonation of chlorobenzene with concentrated sulphuric acid?
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.
\[\begin{array}{cc}
\ce{CH3}\phantom{.................}\\
|\phantom{...................}\\
\ce{CH3 - C - CH2 - Cl->[Na/dry ether]A}\\
|\phantom{..................}\\
\ce{CH3}\phantom{................}
\end{array}\]
Observe the following and answer the question given below:
Comment on the bond length of C-X bond in it.
Observe the following and answer the question given below:
Can react by SN1 mechanism? Justify your answer.
Define and explain the SN1 mechanism with a suitable example.
What is the action of following on ethyl bromide?
alcoholic sodium hydroxide
Identify the chiral molecule from the following.
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 a reason for the following:
Ethoxy ethane with conc. HI at 373 K gives C2H5OH and CH3I but not CH3OH and C2H5I.
Which of the following reagent is used for conversion of alkyl halide into nitrile?
