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प्रश्न
How do you convert the following:
Ethanol to propanenitrile
How the following conversion can be carried out?
Ethanol to propanenitrile
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उत्तर १
\[\ce{\underset{Ethanol}{CH3 - CH2 - OH} ->[red P/Br2] \underset{Bromoethane}{CH3 - CH2 - Br} ->[KCN, aq{.} ethanol]\underset{Propanenitrile}{CH3 - CH2 - CN}}\]
उत्तर २
\[\ce{\underset{Ethanol}{CH3CH2OH} ->[P/I2, \Delta] \underset{Iodoethane}{CH3CH2I} ->[KCN/EtOH-H2O][nucleophilic substitution] \underset{Propanenitrile}{CH3CH2CN}}\]
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संबंधित प्रश्न
Discuss the mechanism of alkaline hydrolysis of bromomethane.
Write the structure of an isomer of compound C4H9Br which is most reactive towards SN1 reaction
In the following pair of halogen compounds, which compound undergoes a faster SN1 reaction?
Which compound in the following pair will react faster in SN2 reaction with OH−?
CH3Br or CH3I
How will you bring about the following conversion?
Toluene to benzyl alcohol
Arrange the compounds of the following set in order of reactivity towards SN2 displacement:
2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane
SN1 reactions are accompanied by racemization in optically active alkyl halides.
Given reasons: SN1 reactions are accompanied by racemization in optically active alkyl halides.
What is the action of the following on ethyl bromide
alcoholic solution of potassium hydroxide.
What is the action of the following on ethyl bromide:
moist silver oxide
Which compound in the following pair reacts faster in SN2 reaction with OH–?
- CH3Br or CH3
- CH3Cl, (CH3)3CCl
Which of the following is an example of SN2 reaction?
SN1 reaction of alkyl halides lead to ___________.
Assertion: KCN reacts with methyl chloride to give methyl isocyanide.
Reason: CN– is an ambident nucleophile.
Read the passage given below and answer the following question:
Nucleophilic substitution reaction of haloalkane can be conducted according to both SN1 and SN2 mechanisms. However, which mechanism it is based on is related to such factors as the structure of haloalkane, and properties of leaving group, nucleophilic reagent and solvent.
Influences of halogen: No matter which mechanism the nucleophilic substitution reaction is based on, the leaving group always leave the central carbon atom with electron pair. This is just the opposite of the situation that nucleophilic reagent attacks the central carbon atom with electron pair. Therefore, the weaker the alkalinity of leaving group is, the more stable the anion formed is and it will be more easier for the leaving group to leave the central carbon atom; that is to say, the reactant is more easier to be substituted. The alkalinity order of halogen ion is I− < Br− < Cl− < F− and the order of their leaving tendency should be I− > Br− > Cl− > F−. Therefore, in four halides with the same alkyl and different halogens, the order of substitution reaction rate is RI > RBr > RCl > RF. In addition, if the leaving group is very easy to leave, many carbocation intermediates are generated in the reaction and the reaction is based on SN1 mechanism. If the leaving group is not easy to leave, the reaction is based on SN2 a mechanism.
Influences of solvent polarity: In SN1 reaction, the polarity of the system increases from the reactant to the transition state, because polar solvent has a greater stabilizing effect on the transition state than the reactant, thereby reduce activation energy and accelerate the reaction. In SN2 reaction, the polarity of the system generally does not change from the reactant to the transition state and only charge dispersion occurs. At this time, polar solvent has a great stabilizing effect on Nu than the transition state, thereby increasing activation energy and slow down the reaction rate. For example, the decomposition rate (SN1) of tertiary chlorobutane in 25℃ water (dielectric constant 79) is 300000 times faster than in ethanol (dielectric constant 24). The reaction rate (SN2) of 2-bromopropane and NaOH in ethanol containing 40% water is twice slower than in absolute ethanol. In a word, the level of solvent polarity has influence on both SN1 and SN2 reactions, but with different results. Generally speaking, weak polar solvent is favorable for SN2 reaction, while strong polar solvent is favorable for SN1 reaction, because only under the action of polar solvent can halogenated hydrocarbon dissociate into carbocation and halogen ion and solvents with a strong polarity is favorable for solvation of carbocation, increasing its stability. Generally speaking, the substitution reaction of tertiary haloalkane is based on SN1 mechanism in solvents with a strong polarity (for example, ethanol containing water).
SN1 mechanism is favoured in which of the following solvents:
Cyanide ion acts as an ambident nucleophile. From which end it acts as a stronger nucleophile in aqueous medium? Give reason for your answer.
Why are aryl halides less reactive towards nucleophilic substitution reactions than alkyl halides?
CCl4 is insoluble in water because:-
The number of chiral carbons present in the molecule given below is ______.
Which one of the following chlorohydrocarbons readily undergoes solvolysis?
