Advertisements
Advertisements
Question
What is dehydrohalogenation? State the rule for the formation of the preferred product of dehydrohalogenation.
Solution
- Dehydrohalogenation reaction: When an alkyl halide having at least one β-hydrogen is boiled with an alcoholic solution of potassium hydroxide (KOH), it undergoes elimination of hydrogen atom from β-carbon and halogen atom from α-carbon resulting in the formation of an alkene. As hydrogen and halogen are removed in this reaction, it is termed a dehydrohalogenation reaction.
- Saytzeff’s rule:
Statement - “In dehydrohalogenation reaction, the preferred product is that alkene which has a greater number of alkyl groups attached to doubly bonded carbon atoms.”
RELATED QUESTIONS
from the following pair would undergo SN2 faster from the other?
a. 
b. 
Name the reagent used to bring about the following conversion.
1-Chloropropane to 1-nitropropane
Name the reagent used to bring about the following conversion.
Chlorobenzene to biphenyl
Convert the following:
Benzyl alcohol to benzyl cyanide
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.
Propane nitrile can be prepared by heating ____________
Nucleophilic substitution reaction of 2, 4-dinitrochlorobenzene is faster than p-nitrochlorobenzene. Give reason.
Write the correct order of increasing ease of dehydrohalogenation.
\[\ce{\underset{\text{(I)}}{CH3 - CH2 - CH2 - Cl}}\]
\[\ce{\underset{\text{(II)}}{CH3 - CH(Cl) - CH3}}\]
\[\begin{array}{cc}
\ce{CH3}\\
|\\
\ce{CH3-C-Cl}\phantom{...}\\
|\\
\ce{CH3}\\
\ce{(III)}
\end{array}\]
Explain the factors affecting SN1 and SN2 mechanism.
Explain aqueous alkaline hydrolysis of tert. butyl bromide.
In alkaline hydrolysis of tertiary butyl bromide, ____________.
Which of the following is a primary halide?
The least reactive towards nucleophilic addition reactions is ____________.
Which one is most reactive towards nucleophilic addition reaction?
What type of hybridisation is present in carbocation formed during the alkaline hydrolysis of 1- bromo-1- phenyl ethane?
What is the major product obtained in the sulphonation of chlorobenzene with concentrated sulphuric acid?
Convert the following.
p-Nitrochlorobenzene to p-nitrophenol
Which of the following statements is incorrect regarding the dehydrohalogenation of alkenes?
The order of reactivity of the given haloalkanes towards nucleophiles is:
The compound that reacts the fastest with sodium methoxide is ______.
Complete the following reaction giving major products.
\[\begin{array}{cc}
\ce{CH3}\phantom{.......}\\
|\phantom{.........}\\
\ce{CH3 - c - CH2 - Cl ->[Na/dry ether]}\\
|\phantom{.........}\\
\ce{CH3}\phantom{.......}
\end{array}\]
Observe the following and answer the question given below:
Can react by SN1 mechanism? Justify your answer.
What is the action of following on ethyl bromide?
alcoholic sodium hydroxide
Complete the following reaction giving major product.
\[\begin{array}{cc}
\ce{CH3}\phantom{...............}\\
|\phantom{..................}\\
\ce{CH3 - C - CH2 - Cl ->[Na/dry ether]A}\\
|\phantom{...................}\\
\ce{CH3}\phantom{.................}
\end{array}\]
Complete the following reaction giving major product.
\[\begin{array}{cc}
\ce{CH3}\phantom{................}\\
|\phantom{..................}\\
\ce{CH3 - C - CH2 - Cl ->[Na/dry ether]A}\\
|\phantom{..................}\\
\ce{CH3}\phantom{................}
\end{array}\]
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.
Complete the following reaction giving major product.
\[\begin{array}{cc}
\ce{CH3}\phantom{.................}\\
|\phantom{...................}\\
\ce{CH3 - C - CH2 - Cl ->[Na/dry ether] A}\\
|\phantom{...................}\\
\ce{CH3}\phantom{.................}\\
\end{array}\]
