(1) Cu/300^oC: (i) Dehydrogenation of primary alcohol into aldehyde. (ii) Dehydrogenation of secondary alcohol into ketone. (iii) Dehydration of tertiary alcohol into alkene.

(2) CYCLIC TRIMERISATION: When acetylene is passed through a copper tube heated to about 700^oC, it undergoes cyclic trimerization involving three molecules to form benzene (poor yield). The same process can be carried out in good yield by catalysts Nickel cyanide Ni(CN)₂ and triphenylphosphine (C₆H₅)₃P (in combination).

(3) With a regulated supply of dioxygen and in the presence of catalyst Cu at 523K and 100 atm CH₄ gets converted into CH₃OH.

(4) Ullmann Reaction: Two molecules of aryliodide are coupled by heating with copper powder at around 250^oC to form a biaryl. Two benzene rings are joined together. Aryl bromides and chlorides react only if electron withdrawing groups such as -CN or -NO₂ are attached at ortho or para position.