Question: Is the organic reactant oxidized, reduced, or neither in each of the following reactions?

In the case of organic compounds, what is meant by oxidation-reduction, is the change in the number of carbon-heteroatom bonds and carbon-hydrogen bonds. By calculating the difference in the number of carbon-heteroatom bonds of reactant and product or by calculating the difference in the number of carbon-hydrogen bonds in the reactant and product, it can be found out whether the reactant has been oxidized or reduced.

If the number of carbon-heteroatom bonds increases and the number of the carbon-hydrogen bond decreases in going from reactants to the products, the reactant is said to be oxidized. This is because when carbon makes a bond with more electronegative heteroatom its electron density is decreased, and thus oxidation occurs.

On the other hand, If the number of carbon-heteroatom bonds decreases or the number of the carbon-hydrogen bonds increases in going from reactants to the products, the reactant is said to be reduced. This is because, when carbon makes a bond with hydrogen, it gains electron density, so that it is said to be reduced.

In the given reaction, 1-butyne is giving 1-butene, as the number of C-H bonds is increased in going from reactant to the product, and hence, the reactant is reduced.

In the given reaction, toluene is giving benzoic acid, which is oxidation, as the number of C-H bonds is decreasing.