$C_2H_6+Br_2\overset{as}{\rightarrow}C_2H_5Br+HBr$$C_2H_5Br+NaOH\rightarrow C_2H_5OH+NaBr$
$(C_2H_5Br+H_2O\overset{OH^-}{\rightarrow}C_2H_5OH+HBr)$
$2C_2H_5OH+O_2\overset{Cu}{\rightarrow}2CH_3CHO+2H_2O$
$(C_2H_5OH+CuO\rightarrow CH_3CHO+H_2O+Cu)$
$2CH_3CHO+O_2\overset{Mn^{2+}}{\rightarrow}2CH_3COOH$