If 1– alkynes reacts with Cu2Cl2, NH4Cl and air, oxidative coupling takes place and dimerised product alkadynes are formed. Remember dimerisation is the only process where double bonds are intact, while in tetramerisation ethyne form boat shape molecule cyclooctatetraene which is nonaromatic in nature.
(xiv) Convert alkane into alkene and alkene into alkyne
(1) Cl2/hv (2) alc KOH
(xv) How we convert Lower alkynes into higher alkyne ?
(xvi) Reaction with Hot aq. KMnO4 or K2Cr2O7
(xvii) Oxidation :
(b) Oxidation by alkaline KMnO4 :
© Oxidation by H2CrO4 or acidified K2Cr2O7 :
(d) Oxidation by acidified KMnO4 :
(e) Oxidation by selenium dioxide :