Give the method of preparation of ethyne (acetylene) from vicinal dihalides.
(N/A) Vicinal dihalides are compounds in which two halogen atoms are attached to adjacent carbon atoms.
When vicinal dihalides are treated with alcoholic potassium hydroxide $(KOH)$,they undergo dehydrohalogenation to form vinyl halides,which then react with sodamide $(NaNH_2)$ to form ethyne.
The reaction is as follows:
$CH_2Br-CH_2Br + 2KOH (\text{alc.}) \longrightarrow CH \equiv CH + 2KBr + 2H_2O$
Alternatively,using $NaNH_2$ in liquid ammonia:
$CH_2Br-CH_2Br \xrightarrow{NaNH_2 / liq. NH_3} CH \equiv CH$
When vicinal dihalides are treated with alcoholic potassium hydroxide $(KOH)$,they undergo dehydrohalogenation to form vinyl halides,which then react with sodamide $(NaNH_2)$ to form ethyne.
The reaction is as follows:
$CH_2Br-CH_2Br + 2KOH (\text{alc.}) \longrightarrow CH \equiv CH + 2KBr + 2H_2O$
Alternatively,using $NaNH_2$ in liquid ammonia:
$CH_2Br-CH_2Br \xrightarrow{NaNH_2 / liq. NH_3} CH \equiv CH$
Explore More
Similar Questions
Predict the correct intermediate and product in the following reaction: $CH_3-C \equiv CH \xrightarrow[HgSO_4]{H_2O, H_2SO_4} \text{Intermediate } (A) \to \text{Product } (B)$
MediumNEET 2017
View SolutionWhich of the following order of reagents is chosen to prepare $1, 3-$butadiene from $C_2H_2$?
Medium
View SolutionThe compound $X$ on reaction with $HgSO_4 + H_2SO_4$ gives $Y$ which on oxidation gives acetic acid. $X$ is
Difficult
View SolutionPredict the product $C$ obtained in the following reaction of $1-$butyne: $CH_3-CH_2-C \equiv CH + HCl$ $\rightarrow B$ $\xrightarrow{HI} C$
MediumAIPMT 2007
View SolutionThe structure of the product $(Z)$ in the reactions given below is:
$HC \equiv CH$ $\xrightarrow{NaNH_2, CH_3COCH_3, H^{+}} X$ $\xrightarrow{Hg^{2+}, H_3O^{+}, H_2O} Z$
$HC \equiv CH$ $\xrightarrow{NaNH_2, CH_3COCH_3, H^{+}} X$ $\xrightarrow{Hg^{2+}, H_3O^{+}, H_2O} Z$
Difficult
View SolutionVedclass Products
For Students
Vedclass Test Series
Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.
Start Free TrialFor Teachers
Exam Paper Generator
Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.
Try FreeFor Institutes
Online Exam Module
Live online exams with unlimited students, 360° analytics & white-label branding.
See Demo