Alkynes Flashcards
How will you convert Ethynes to Benzene?
Ethyne Gives{Red Hot Iron Tube, 873K} Benzene
What is Monobromination? What is Monochlorination?
Adding Br by reacting substance with BR2 in presence of Heat, HV or Febr3 or other methods. Adding Cl in presence of heat or HV or other methods.
Catalyst for converting Tri-Halogen derivatives to alkynes?
Ag powder
What is Soda amide used for?
For Dehydrohalogenation
NaNh2
Soda Amide
States of Alkynes:
The first three are gases, The next 8 are liquids and higher ones are solids
Which is more polar…. alkane alkene or alkyne and why??
Alkynes are more polar among alkane, alkene and alkyne. This is because of the electron density near the triple bond.
Which is more acidic But1yne or But2yne?
But1yne due to acidic hydrogen
CH≡CH + 2{CU(NH3)2}OH gives? Also color and catalyst
Catalyst: Heat
Product: CuC≡CCu which is Red ppt
Addition of Halogens to alkynes is which type of addition?
Trans/Anti addition
Addition of hydrogen halides to Alkynes forms?
Geminal dihalides
XCH=CHX + HX
X2CH-CH3{Gem Dihalide}
CH≡CH + H2O gives
Nothing. Alkynes are immiscible and do not react with water like alkanes and alkenes. For alkynes to react with water, you need mercuric sulphate and dilute sulphuric acid at 333K and this forms Vinyl alcohols.
CH2=CH-OH Isomerizes to give
CH3-CH=O. Keto Enol tautomerism
Use of Polyacetylene
Conducts electricity. Film is used as electrodes in batteries. These thin films are good conductors, lighter and cheaper than metal conductors
For white ppt with Agno3, conditions?
The triple bond must be terminal, for example Byt2yne won’t give white ppt with AGNO3 whereas But1yne will. Also presence of Cl- ion is required
(I)Hydroboration of terminal dialkynes
(II)Ozonolysis of Alkynes
(III)Oxymercuration produces
(I)Hydroboration of terminal dialkynes produces enols by anti-markovnikoff’s addition which rearrange to produce dialdehyde.
(II)Ozonolysis produces dicarboxylic acid and Co2 by oxidative cleavage.
(III)Oxymercuration also produces enol by markovnikoff’s addition which rearranges to produce diketone product
The total number of isomers of a disubstituted benzene compound is
3 as 1,2 or 1,6(ortho) and 1,3 or 1,5(meta) and 1,4(para) showing position isomerism
Alkynes on reaction with Hg2+/H+/333K and H2O gives?
Ketones
The lesser the distance between EWG and EDG, the less stable
Given
HgSo4 and H2So4 as ctalysts convert Alkynes to
Ketone form, Also said Ketone form posses no Carbon Carbon double or tiple bonds. Also tis rule follows MArkonikov rule
