A preparation method of carboxylic acids or ketones using ozone, singlet state oxygen atom O(.sup.1D) or hydroxyl free radical is provided. The method includes: filling ozone, singlet state oxygen atom O(.sup.1D) and/or hydroxyl free radical to cycloalkanes or benzenes at a pre-determined temperature and a pre-determined pressure in the presence or absence of light irradiation to produce carboxylic acids or ketones. The reaction occurs at room temperature and atmospheric pressure without producing harmful side products. The preparation method is a simple, low energy consuming, and eco-friendly method.

A preparation method of carboxylic acids or ketones using ozone, singlet state oxygen atom O(.sup.1D) or hydroxyl free radical is provided. The method includes: filling ozone, singlet state oxygen atom O(.sup.1D) and/or hydroxyl free radical to cycloalkanes or benzenes at a pre-determined temperature and a pre-determined pressure in the presence or absence of light irradiation to produce carboxylic acids or ketones. The reaction occurs at room temperature and atmospheric pressure without producing harmful side products. The preparation method is a simple, low energy consuming, and eco-friendly method.

Provided is a method of producing an anhydride of an organic mono-acid comprising contacting an organic mono-acid and a thermally regenerable anhydride to produce the anhydride of the organic mono-acid, and either a diacid of the regenerable anhydride, a partially hydrolyzed regenerable anhydride, or both. In a particular example, acetic acid and glutaric anhydride can be reacted to form acetic anhydride.

Provided is a method of producing an anhydride of an organic mono-acid comprising contacting an organic mono-acid and a thermally regenerable anhydride to produce the anhydride of the organic mono-acid, and either a diacid of the regenerable anhydride, a partially hydrolyzed regenerable anhydride, or both. In a particular example, acetic acid and glutaric anhydride can be reacted to form acetic anhydride.