Methanediol, also known as formaldehyde monohydrate or methylene glycol, is a chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 with chemical formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 CH₄O₂, or H₂C(OH)₂. It is the simplest geminal diol

Geminal diol

A geminal diol is any organic compound having two hydroxyl functional groups bound to the same carbon atom.The simplest geminal diol is methanediol CH4O2 or H2C2...

, and formally the second simplest carbohydrate

Carbohydrate

A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

 (after formaldehyde

Formaldehyde

Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

).

Methanediol is a product of the hydration

Hydration reaction

In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl group and a hydrogen cation are added to the two carbon atoms bonded together in the carbon-carbon double bond which makes up an alkene functional group. The reaction usually runs in a strong acidic, aqueous...

 of formaldehyde

Formaldehyde

Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

 H₂C=O, and predominates in water solution: the equilibrium constant being about 10³, and a 5% by weight solution of formaldehyde

Formaldehyde

Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

 in water is 80% methanediol.

The compound is of some relevance to astrochemistry

Astrochemistry

Astrochemistry is the study of the abundance and reactions of chemical elements and molecules in the universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar System and the interstellar medium...

.

Methanediol is listed as one of the main ingredients of "Brazilian blowout

Brazilian hair straightening

Brazilian hair straightening is a method of temporarily straightening hair by sealing the hair with a liquid keratin and a preservative solution with a flat hair iron.- Characteristics :The Brazilian Keratin Treatment is a...

", a hair-straightening formula marketed in the US — even though the California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

-based manufacturer claims that the product contains no formaldehyde.