Dehydrohalogenation for Alkenes

Q. In $S_{N}2$ reaction, the correct order of reactivity for the following compounds is:
$C{H}_{3}Cl,C{H}_{3}C{H}_{2}Cl,(C{H}_3{)}_{2}CHCl$ and $(C{H}_3{)}_{3}CCl$

1. $C{H}_{3}Cl>(C{H}_3{)}_{2}CHCl>C{H}_{3}C{H}_{2}Cl>(C{H}_3{)}_{3}CCl$
2. $C{H}_{3}Cl>C{H}_{3}C{H}_{2}Cl>(C{H}_3{)}_{2}CHCl>(C{H}_3{)}_{3}CCl$
3. $C{H}_{3}C{H}_{2}Cl>C{H}_{3}Cl>(C{H}_3{)}_{2}CHCl>(C{H}_3{)}_{3}CCl$
4. $(C{H}_3{)}_{2}CHCl>C{H}_{3}C{H}_{2}Cl>C{H}_{3}Cl>(C{H}_3{)}_{3}CCl$

Q.

Benzene reacts with ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{Cl}$ in presence of ${\mathrm{AlCl}}_3$ produces

Q. The product of reaction of alcoholic silver nitrate with ethyl bromide are

1. Ethyl nitrite
2. Ethane
3. Ethene
4. Nitroethane

Q. The major product of the following reaction is:

1. 
2. 
3. 
4. 

Q.

In dehydrohalogenation reactions the preferred product is that alkene which has the greatest number of alkyl groups attached to the doubly bonded carbon atoms. This rule is known as:

1. Saytzeff's rule

2. Markoniknov's rule

3. Anti markoniknov's rule

4. None of these

Q.

Write short notes on chain-shortening and chain-lengthening reactions for sugars.

Q.

Predict all the alkanes that would be formed by dehydrohalogenation of the following halides with sodium ethoxide in ethanol and identify the major alkene :

1-bromo-1-menthylcyclohexane

2 -chloro-2-methylbutane

3-bromo- 2, 2, 3-Trimethylpentane.

Q.

Which of the following is the major product when 1-butanol is heated with concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$?

1. 1-butene

2. Cis-2-butene

3. Trans-2-butene

4. All of these

Q.

The dehydrohalogenation of neopentyl bromide with alcoholic KOH mainly gives

1. 2, 2-dimethyl-1-butene
2. 2-butene
3. 2-methyl-1-butene

4. 2-methyl-2-butene

Q. Which of the following compounds undergoes dehydrochlorination most easily when treated with alcoholic $KOH$ ?

1. 
2. 
3. 
4. 

Q. Which of the following compound(s) will not undergo $\beta$- Elimination reaction on reacting with alcoholic KOH?

1. 
2. 
3. 
4. 

Q. A gas formed by the action of alcoholic KOH on ethyl iodide, decolourises alkaline $KMn{O}_4$. The gas is

1. $C_2{H}_6$
   
2. $C{H}_4$
   
3. $C_2{H}_2$
   
4. $C_2{H}_4$

Q. How many different possible alkenes are formed when 2-chlorobutane is treated with ethanolic solution of KOH?

1. 1
2. 2
3. 3
4. 4

Q. 2-chlorobutane is heated with alcoholic NaOH, the product formed in larger amount is

1. 1-Butene
2. 1-Butyne
3. 2-Butene
4. All of these

Q. Assertion:-Tert. butyl alcohol on heating with conc. H2SO4 at 413 K gives 2-methyl propane as the main product and not di-tert. butyl ether. Reason:- All alcohols are readily dehydrated with conc. H2S04.

Q. The correct reactivity order of following C = C / $C\equiv$ C bonds towards $B{r}^{\oplus }$ is:

1. 4 > 3 > 2 > 1
2. 3 > 2 > 1 > 4
3. 1 > 3 > 4 > 2
4. 1 > 3 > 2 > 4

Q. $C{H}_3-C{H}_2-Cl\stackrel{alc.KOH}{\to }A.$ the product is

1. $C{H}_{3}CHO$
   
2. $C{H}_2=C{H}_2$
3. $C{H}_{3}C{H}_{2}OC{H}_{3}C{H}_3$
   
4. $C{H}_{3}C{H}_{2}OK$
   

Q. 44. In the dehydrohalogenation of 2-bromobutane, which conformation leads to the formation of cis-2-butene?

Q. 1-Chlorobutane on reaction with alcoholic KOH gives

1. 1-Butanol
2. 1-Butene
3. 2-Butene
4. 2-Butanol

Q. Monohalides on reacting with alcoholic KOH give

1. Alkanes
2. Alkenes
3. Alkynes

4. Aromatic hydrocarbons

Q. Ethyl bromide gives ethylene when reacted with

1. Dilute $H_{2}S{O}_4$
2. Ethyl alcohol
3. Aqueous KOH
4. Alcoholic KOH

Q. Consider the following reaction $C{H}_3-\stackrel{\stackrel{C{H}_3}{|}}{\underset{\underset{Br}{|}}{C}}-C{H}_{2}C{H}_3\stackrel{Alc.KOH}{⟶}$

which of the following alkene will be the major product?

1. I
2. II
3. both will be formed in equal amount
4. None of the above

Q. The final product formed when ethyl bromide is treated with excess of alcoholic KOH is

1. Ethylene
2. Ethane
3. Ethyne
4. Vinyl bromide

Q. The most suitable reagent for the given conversion is :


\( \stackrel{\eta}{\longrightarrow} \)

Q. Which would undergo $S_{N}1$ reaction faster in the following pair and why?
$C{H}_3-C{H}_2-Br\text{and}C{H}_3-\underset{\underset{Br}{|}}{\stackrel{\stackrel{C{H}_3}{|}}{C}}-C{H}_3$

Q. 2-chlorobutane is heated with alcoholic NaOH, the product formed in larger amount is

1. 1-Butene
2. 1-Butyne
3. 2-Butene
4. All of these

Q. In which of the following reactions, only single isomer of alkene is formed?

1. $C_6{H}_5-C{H}_2-C{H}_2-C{H}_2-Br\underset{Ethanol}{\overset{KOH}{\to }}$
2. $C_6{H}_5-C{H}_2-\stackrel{\stackrel{Br}{|}}{C}H-C_6{H}_5\underset{Ethanol}{\overset{KOH}{\to }}$
3. 
4. 

Q. A gas formed by the action of alcoholic KOH on ethyl iodide, decolourises alkaline $KMn{O}_4$. The gas is

1. $C_2{H}_2$
   
2. $C_2{H}_6$
   
3. $C_2{H}_4$
4. $C{H}_4$
   

Q. Which of the following amines will not give Hoffman-Bromamide reaction?

1. 
2. 
3. 
4. 

Q. In which of the following adduct is formed most easily?

1. $(Si{H}_3{)}_{2}O+BB{r}_3$
2. $(C{H}_3{)}_{2}O+B{F}_3$
3. $(Si{H}_3{)}_{2}O+B{F}_3$
4. $(C{H}_3{)}_{2}O+BB{r}_3$