Dehydrohalogenation of Dihalides

Q.

What is a dehydrohalogenation reaction?

Q.

How will you convert ethane into butane?

Q. Propyne is formed by heating 1, 2-dibromopropane with :

1. $C_2{H}_{5}ONa$
2. Alc. KOH and sodamide
3. Aqueous $KMn{O}_4$
4. dil. $H_{2}S{O}_4$ and then $KMn{O}_4/H^{+}$

Q. When haloalkane or alkyl halide with a $\beta$ hydrogen is heated with alcoholic solution of KOH, elimination of a hydrogen atom from $\beta$ carbon and halogen atom from $\alpha$-carbon occurs as a result, alkene is formed as product. Since $\beta$ hydrogen atom is involved in the elimination reaction, it is often called $\beta$ elimination.

$C{H}_{3}FCHC{H}_{2}C{H}_{2}C{H}_3\underset{C{H}_{3}OH}{\stackrel{C{H}_3{O}^{-}}{\to }}R\left(MajorProduct\right)$
What is the major product (R)?

1. 
2. $C{H}_{3}CH=CHC{H}_{2}C{H}_3$
3. $C{H}_2=CHCH\left)2CH\right)2C{H}_3$
4. 

Q. Cumene process is the most important commercial method for the manufacture of phenol.
Cumene is:

1. (1-methylethyl) benzene
2. ethyl benzene
3. vinyl benzene
4. propyl benzene

Q.

CH3CH2OH react with CH3MgBr product is....... Please please show the reaction mechanism....

Q. Vicinal dihalides on treatment with alcoholic KOH undergoes

1. dehydrohalogenation
2. dehydration
3. None of the above
4. dehalogenation

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

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

Q. when 1-chloro-2, 2-dimethyl propane is treated with NaOH /DMSO then reaction does not occur but when treated with aqueous NaOH then it give Sn1 reaction .why??

Q.

The chemical name of CH₃OCH₃ is …?

Q. Aniline undergoes condensation to form Schiff base on reacting with :

1. acetyl chloride
2. ammonia
3. acetone
4. benzaldehyde.

Q. The product formed by aldol condensation between benzaldehyde and acetone is benzalacetone. Its structure is:

1. $C_6{H}_5-C{H}_2-\stackrel{O}{\stackrel{||}{C}}-CH=C{H}_2$
2. $C_6{H}_5-CH=CH-\stackrel{O}{\stackrel{||}{C}}-C{H}_3$
3. $C_6{H}_5-CH=C(C{H}_3{)}_2$
4. $C_6{H}_5-\stackrel{O}{\stackrel{||}{C}}-CH=CH-C{H}_3$

Q. The reaction of $C{H}_{3}CHO$ and $N{H}_2-N{H}_2$ and the formation of $C{H}_3-CH=N-N{H}_2$ is an example of :

1. Nucleophilic substitution reaction
2. Elimination reaction
3. Condensation reaction
4. Electrophilic substitution reaction

Q. A compound ${}^{\prime }{X}^{\prime }$ having molecular formula $C_5{H}_8$, reacts with ammoniacal $AgN{O}_3$ to give a white precipitate and reacts with excess of $KMn{O}_4$ to give the acid, $(C{H}_3{)}_{2}CH-COOH$. Therefore, $X$ is:

1. $C{H}_2=CH-CH=CH-C{H}_3$
2. $C{H}_3-C{H}_2-C\equiv C-C{H}_3$
3. $(C{H}_3{)}_{2}CH-C\equiv CH$
4. $(C{H}_3{)}_{2}C=C=C{H}_2$

Q. Total sum of $\alpha -H$ in major product(s) (alkene) of each of the following reactions.

Q. Propyne is formed by heating 1, 2-dibromopropane with :

1. $C_2{H}_{5}ONa$
2. Alc. KOH and sodamide
3. Aqueous $KMn{O}_4$
4. dil. $H_{2}S{O}_4$ and then $KMn{O}_4/H^{+}$

Q. n-propylbromide on treating with alcoholic KOH produces

1. propene
2. propane
3. propyne
4. propanol

Q.

Ethylamine can be prepared by the action of bromine and caustic potash on

[CPMT 1994]

1. Acetamide

2. Propionamide

3. Formamide

4. Methyl cyanide

Q. Aldehydes on reaction with $N{H}_2-N{H}_2$ forms:

1. aniline
2. hydrazone
3. nitrobenzene
4. none of the above

Q.
For the given reaction the major product 'B' is :

1. $C{H}_2=CH-CH=C{H}_2$
2. $C{H}_3-C\equiv C-C{H}_3$
3. $C{H}_3-C{H}_2-C\equiv CH$
4. $C{H}_3-CH=C=C{H}_2$

Q. Vicinal dihalides on treatment with alcoholic KOH undergoes

1. dehydrohalogenation
2. dehydration
3. dehalogenation
4. None of the above

Q. For the given reaction , choose the correct option(s) :

1. A is propene
2. A is propyne
3. B is propylbenzene
4. B is 1, 3, 5-trimethylbenzene

Q.

Which reagent will convert $\mathrm{RCOR}$ group into $\mathrm{RR}\mathrm{C}\left({\mathrm{C}}_6{\mathrm{H}}_5\right)\mathrm{OH}$?

Q. Identify compound X in the following aqueous of reaction:

1. 
2. 
3. 
4. 

Q. The reagent(s) for the following conversion,

1. alcoholic KOH
2. aqueous KOH followed by $NaN{H}_2$
3. $Zn/C{H}_{3}OH$
4. alcoholic KOH followed by $NaN{H}_2$

Q. How are the products of the following two reactions related? 1. Reaction of 1-Phenylbut-1-yne with dil. H2SO4 and Hg(2+) 2. Reaction of 1-Phenylbut-1-yne with (i) BH3 +THF (ii) H2O2 + OH(-) . Give the mechanism of the reactions too.

Q. The reagent used to convert nitrobenzene to azobenzene is :

1. $Sn/HCl$
2. $Zn/Na-Hg$
3. $LiAl{H}_4$
4. $H_2$ and $Ni$

Q. The reagent(s) for the following conversion
is/are :

1. Alcoholic $KOH$
2. Alcoholic $KOH$ followed by $NaN{H}_2$
3. Aqueous $KOH$ followed by $NaN{H}_2$
4. $Zn/C{H}_{3}OH$

Q. Gem dihalides on treatment with alcoholic KOH gives :

1. cycloalkanes
2. alkene
3. alkyne
4. alkane

Q. 2, 2-dichloropropane $\stackrel{Aq.KOH}{\to }A\underset{reduction}{\overset{Clemmensen}{\to }}B$, B is

1. Propene
2. Propanol
3. Propane
4. Ethane