Generic example of an anhydride.

In chemistry, an anhydride is a compound that can be considered as derived from another compound by subtracting the molecules of water. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as

For example:

2 NaOH - H₂O → Na₂O

H₂SO₄ - H₂O → SO₃

Thus sodium oxide is an anhydride of sodium hydroxide, and sulfur trioxide is an anhydride of sulfuric acid. Sodium hydroxide ( Na[[hydroxide OH]]) also known as Lye, caustic soda and (incorrectly according to IUPAC nomenclature Sodium oxide is a Chemical compound with the formula Na 2 O. It is used in Ceramics and Glasses Treatment with water Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. Sulfur trioxide (also spelled sulphur trioxide) is the chemical compound with the formula SO3 Sodium oxide is a Chemical compound with the formula Na 2 O. It is used in Ceramics and Glasses Treatment with water Sodium hydroxide ( Na[[hydroxide OH]]) also known as Lye, caustic soda and (incorrectly according to IUPAC nomenclature Sulfur trioxide (also spelled sulphur trioxide) is the chemical compound with the formula SO3 Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid.

In organic chemistry, the compounds most commonly involved are carboxylic acids. Carboxylic acids are Organic acids characterized by the presence of a Carboxyl group, which has the formula -C(=OOH usually written -COOH or -CO2H

2 CH₃COOH - H₂O → (CH₃CO)₂O

Compounds involved are often acids or bases; in such cases, the anhydrides can be called acid anhydrides or base anhydrides. Acetic acid, also known as ethanoic acid, is an organic chemical compound, giving Vinegar its sour taste Acetic anhydride is the Chemical compound with the formula (CH3CO2O In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are In Chemistry, a base is most commonly thought of as an aqueous substance that can accept Protons This refers to the Brønsted-Lowry theory of acids and An acid anhydride is an Organic compound that has two Acyl groups bound to the same Oxygen atom This does not imply that the anhydrides are not themselves acids or bases; they are. But the more hydrated forms may be more familiar or convenient.

Anhydride is sometimes used as a synonym for acid anhydride.

Following are two reactions, one with a typical acid and base, one with their anhydrides. The first one is more practical.

2 NaOH (aq) + H₂SO₄ (aq) → Na₂SO₄ + 2H₂O (l)

Na₂O (s) + SO₃ (g) → Na₂SO₄ (aq)

In general, anhydrides are more reactive than their corresponding acids, as they can react with water to form their corresponding acid. They often are good dehydrating agents. Acetic anhydride is useful in the acetylation of salicylic acid, as using acetic acid to perform the reaction leaves water behind, which can destroy the product, acetylsalicylic acid, or aspirin. Acetic anhydride is the Chemical compound with the formula (CH3CO2O Acetylation (or in IUPAC nomenclature ethanoylation) describes a reaction that introduces an Acetyl Functional group into an Organic compound Acetic acid, also known as ethanoic acid, is an organic chemical compound, giving Vinegar its sour taste Aspirin, or acetylsalicylic acid (ASA (əˌsɛtɨlsælɨˌsɪlɨk ˈæsɨd is a Salicylate drug, often used as an Analgesic to relieve

In biology, most of the high-energy phosphate compounds are formed from the condensation of the phosphate ion with a phosphorylated sugar. High-energy phosphate can mean one of two things The phosphate-phosphate bonds formed when compounds such as Adenosine diphosphate and Adenosine triphosphate A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. The resulting pyrophosphate bond is a classic anhydride bond. In Chemistry, the Anion, the Salts and the Esters of Pyrophosphoric acid are called pyrophosphates.

See also

• Acid anhydride