Saved Bookmarks
| 1. |
How will you bring about the following conversions? (i) Ethanol to but-1-yne (ii) Ethane to bromoethene (iii) propene to 1-nitropropane (iv) toluene to benzyl alcohol (v) Propene to propyne (vi) Ethanol to ethyl fluoride (vii) Bromomethane to propanone (viii) But-1-ene to but-2-ene (ix) 1-Chlorobutane to n-octane. (x) Benzene to biphenyl. |
Answer» Solution : (v) `underset("Propene")(CH_(3)-CH=CH_(2)) OVERSET(Br_(2)//C Cl_(4))to underset("1,2-Dibromopropane")(CH_(3)-underset(Br)underset(|)(C)H-underset(Br)underset(|)(C)H_(2)) underset(-2" HBr")overset(NaNH_(2)//liq.NH_(3),196K)to underset("Propyne")(CH_(3)-C-=CH)` Alternatively, conversion of 1,2-dibromopropane to propyne can be carried out simply by heating with KOH (alc.) but he YIELD is low. the reason being that 1,2-dihaloalkanes can be SMOOTHLY dehydrohalogenated to vinyl HALIDES by heating with KOH (alc.), but vinyl halides being less reactive requrie a much stronger base such a `NaNH_(2)//liq`. `NH_(3)` for dehydrohalogenation to form alkynes. both these steps, can, however, be smoothly carried out simultaneously with `NaNH_(2)//liq.NH_(3)`. (vi) `underset("Ethanol")(CH_(3)CH_(2)OH) underset(-SO_(2),-HCl)overset(SOCl_(2)," pyridine")to underset("Ethyl chloride")(CH_(3)CH_(2)-Cl) underset(-Hg_(2)Cl_(2))overset(Hg_(2)F_(2))to underset("Ethyl fluoride")(CH_(3)CH_(2)-F)` (vii) `underset("Bromomethane")(CH_(3)-Br) underset(C_(2)H_(5)OH-H_(2)O,Delta)overset(KCN(alc))to underset("Acetonitrile")(CH_(3)-CN) overset(CH_(3)MgBr//ether)to [CH_(3)-underset(CH_(3))underset(|)(C)=NMgBr]underset(-NH_(3),-Mg(OH)Br)overset(H^(+)//H_(2)O)to underset("Propyne")(CH_(3)-underset(CH_(3))underset(|)(C)=O)` Alternatively, `underset("ACETYLENE")(HC-=CH) underset(-NH_(3))overset(NaNH_(2)" in liq. "NH_(3),196K)to underset("Sod. acetylide")(HC-=C^(-)+Na^(+)) underset(-NaBr)overset(CH_(3)Br)to underset("Propyne")(CH_(3)-C-=CH) underset(("Addn. of "H_(2)O))overset("Dil. "H_(2)SO_(4),HgSO_(4),333K)to underset("Propanone")(CH_(3)-overset(O)overset(||)(C)-CH_(3))` (viii) `underset("But-1-ene")(CH_(3)CH_(2)CH=CH_(2)) underset("Mark. addn.")overset(HBr )to underset("2-Bromobutane")(CH_(3)-CH_(2)-underset(Br)underset(|)(C)H-CH_(3))underset(-HB r)overset(KOH(alc.),Delta)to underset("But-2-ene (Major product)")(CH_(3)-CH=CH-CH_(3))` (ix) `underset("1-Chlorobutane")(2CH_(3)CH_(2)CH_(2)CH_(2)Cl+2Na) underset(("Wurtz reaction"))overset("Dry ether")to underset("n-Octane")(CH_(3)CH_(2)CH_(2)CH_(2)-CH_(2)CH_(2)CH_(2)CH_(3)+2NaCl)` 
|
|