Alkynes

Question 1

How will you convert Ethynes to Benzene?

Answer 1

Ethyne Gives{Red Hot Iron Tube, 873K} Benzene

Question 2

What is Monobromination? What is Monochlorination?

Answer 2

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.

Question 3

Catalyst for converting Tri-Halogen derivatives to alkynes?

Answer 3

Ag powder

Question 4

What is Soda amide used for?

Answer 4

For Dehydrohalogenation

Question 5

NaNh2

Answer 5

Soda Amide

Question 6

States of Alkynes:

Answer 6

The first three are gases, The next 8 are liquids and higher ones are solids

Question 7

Which is more polar…. alkane alkene or alkyne and why??

Answer 7

Alkynes are more polar among alkane, alkene and alkyne. This is because of the electron density near the triple bond.

Question 8

Which is more acidic But1yne or But2yne?

Answer 8

But1yne due to acidic hydrogen

Question 9

CH≡CH + 2{CU(NH3)2}OH gives? Also color and catalyst

Answer 9

Catalyst: Heat
Product: CuC≡CCu which is Red ppt

Question 10

Addition of Halogens to alkynes is which type of addition?

Answer 10

Trans/Anti addition

Question 11

Addition of hydrogen halides to Alkynes forms?

Answer 11

Geminal dihalides

Question 12

XCH=CHX + HX

Answer 12

X2CH-CH3{Gem Dihalide}

Question 13

CH≡CH + H2O gives

Answer 13

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.

Question 14

CH2=CH-OH Isomerizes to give

Answer 14

CH3-CH=O. Keto Enol tautomerism

Question 15

Use of Polyacetylene

Answer 15

Conducts electricity. Film is used as electrodes in batteries. These thin films are good conductors, lighter and cheaper than metal conductors

Question 16

For white ppt with Agno3, conditions?

Answer 16

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

Question 17

(I)Hydroboration of terminal dialkynes
(II)Ozonolysis of Alkynes
(III)Oxymercuration produces

Answer 17

(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

Question 18

The total number of isomers of a disubstituted benzene compound is

Answer 18

3 as 1,2 or 1,6(ortho) and 1,3 or 1,5(meta) and 1,4(para) showing position isomerism

Question 19

Alkynes on reaction with Hg2+/H+/333K and H2O gives?

Answer 19

Ketones

Question 20

The lesser the distance between EWG and EDG, the less stable

Answer 20

Given

Question 21

HgSo4 and H2So4 as ctalysts convert Alkynes to

Answer 21

Ketone form, Also said Ketone form posses no Carbon Carbon double or tiple bonds. Also tis rule follows MArkonikov rule