Class 11 maharashtra board. contain important material neccesary for exam.

9. Electronic structure of ethyne
• M.F
• Sigma and pi bond
• Triple bond > double bond > single bond.
• 823 Kj mol > 681 KJ mol > 348 KJ mol.
• 120 pm > 133 pm > 154pm
• Bond enthalpy (Bond energy) and bond
length.
• But based on priority prefer first = bond.

12. Nomenclature of alkyne
• Common name- acetylene
• IUPAC name- alk – alk
• If 2 triple bond- diyne and 3 triple
bond- triyne.
• Double bond and triple bond both
first prefer double bond and triple
bond.
eg. But-1en-3-yne.

17. Answer
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21. Uses of acetylene
• Use as oxyacetylene flame which used as
welding of metal.

22. Illuminated lamp

23. Artificial ripening of fruit

24. Manufacture of wastron and wastrosol
• Poison gas.
• Manufacture of acetaldehyde, acetic acid,
oxalic.

25. Method of preparation

26. Method of preparation of alkyne
• From CaC2
• From vicinal dihalide
and Geminal dihalide
• From tetrahalide

27. From calcium carbide
• Industrial method.
• Impurities of phosphine(PH3) and hydrogen
sulphide(H2S) are remove by passing acetylene
through CuSO4 solution.
HO-H + C = C + H-OH → +Ca(OH)2
Ca

28. From vicinal and Geminal dihalide
• By dehydrohalogenation.

29. From vicinal and Geminal dihalide
• From vicinal dihalide:-
Ethylene dibromide + KOH to give vinyl
bromide further react with NaNH2(Sodamide)
to give ethylene.
• From Geminal dihalide:-
1,1 dibromoethane + alc KOH to give vinyl
bromide further react with NaNH2 to give
ethylene.

30. From vicinal and Geminal dihalide
• Weak base give poor yield.
• Strong base give strong yield.eg.
NaNH2.
• 1,2-Dibromo ethane + 2NaNH2 to
give ethylene + 2NaBr + 2NH3.
• 1,1-Dibromo ethane + 2NaNH2 to
give same.

31. From tetrahalide
• Dehalogenation.
• Ethylene tetrabromide(1,1,2,2-
tetrabromoethane) + 2Zn in
presence of alcohol to give
ethyne + 2ZnBr2.

32. Physical properties of alkynes
• C2-C3 – gas
• C4-C8- liquid
• C9- more- solid
• Odour- except C2 all odourless.
• High B.P & M.P & mass & polar.
• Insoluble in water but soluble in
solvent.

33. Reaction of acetylene
• Formation of alkanes
(Hydrogenation)
• Ozonolysis
• Formation of benzene

34. Formation of alkanes
HC ≡ CH + H2 → [CH2 = CH2] → CH3-CH3
Acetylen heated with hydrogen gase in
presence of catalyst Renay Ni, ethane is
formed. Hydrogenation further carried
give alkane.

35. polymerisation
• Formatin of benzen
3CH ≡ CH → benzene.