Tiêu đề 04. Alkyne FLow Carts.pdf ✅

TEACH HIRE DOWNLOAD APP FROM PLAY STORE CLICK HERE ALKYNE GENERAL INTRODUCTION • These are the acyclic hydrocarbons in which unsaturation (CC) is present. • Hybridisation state of triple bonded carbon in alkyne is sp. • Geometry of unsaturated carbon is linear in alkynes. • Bond angle in alkyne on sp carbon atom is 180o. • Their general formula is CnH2n–2 (n = 2, 3, 4, 5 ..........................) • C–C triple bond length is 1.20 Å. • C–H bond length is 1.08 Å. • C–C triple bond energy is 200 kcal/mol. • C–H bond energy is 121 kcal/mol. • Alkyne shows chain, position and functional isomerism. They are functional isomer with cycloalkene and alkadiene. e.g. : Isomers of C4H6 are : CH3–CC–CH3 CH3 –CH2 –CCH CH3 –CH=C=CH2 CH2 =CH–CH=CH2 2-Butyne 1-Butyne 1,2 –Butadiene 1,3-Butadiene Cyclobutene 1-Methyl cyclopropene CH3 3-Methyl cyclopropene CH3 Methylidene cyclopropane CH2 Bicyclobutane PHYSICAL PROPERTIES • Alkynes are colourless, odourless and tasteless. • Lower alkynes are partially soluble in H2O.(It is due to its polarisibility). • Higher alkynes are insoluble in water due to more % of covalent character. • Completely soluble in organic solvents. • Melting point and boiling point increases with molecular mass and decreases with number of branches. • Physical state : C2–C4 → Gaseous C5–C11 → Liquids C12 & above → Solids Boiling point and Melting point  No of branches Molecular weight .
Name Formula B.P. (oC) M.P. (oC) Acetylene HC  CH –75 –82 Propyne CH3– CCH –23 –101.5 1-Butyne CH3CH2– CCH 9 –122 2-Butyne CH3– CC–CH2 27 –24
TEACH HIRE DOWNLOAD APP FROM PLAY STORE CLICK HERE CHEMICAL PROPERTIES OF ALKYNE
H2/Ni R–CH2–CH3 H2/Pd+BaSO4 R–CH=CH2 Br2 R–C––CH HBr HOCl HCN/Ba(CN)2 CH3COOH/Hg+2 H2O/Hg+2 R–C=CH2 NaNH2 R–CC–Na AgNO3 + NH4OH R–CC–Ag (Tollen's Reagent) Cu2Cl2+ NH4OH R–CC–Cu Combustion CO2 + H2O + H C Baeyer Reagent R–C–CHO O3/H2O/Zn ozonolysis K2Cr2O7 or KMnO4/H Strong oxidant R–COOH + CO2  CH3OH (BF3–HgO) R–C–CH3 R–CCH Br Br Br Br HBr/Peroxide OH BH3/H2O2/OH R–CH=CH O R–C–C–H O O R–C=CH2 Br HBr R–C–CH3 Br Br R–CH=CH Br HBr Peroxide R–CH–CH2 Br Br R–C=CH Cl OH HOCl R–C––CH OH Cl OH Cl –H2O R–C––CH Cl O Cl Unstable OH T R–CH2–C–H O (exothermic) (Test of unsaturation) T R–C–CH3 O OCH3 OCH3 R–C–CH3 CN CN R–C–CH3 OCOCH3 OCOCH3 Only for terminal alkyne (Test of unsaturation)