Editing Hydrate (section)

===Organic chemistry===
In organic chemistry, a hydrate is a compound formed by the hydration, i.e. "Addition of water or of the elements of water (i.e. H and OH) to a molecular entity".<ref>{{GoldBookRef|title=Hydration|file=H02876|doi=10.1351/goldbook.H02876|year=2019|accessdate=27 July 2020}}</ref> For example: [[ethanol]], {{chem2|CH3\sCH2\sOH}}, is the product of the [[hydration reaction]] of [[ethene]], {{chem2|CH2\dCH2}}, formed by the addition of H to one C and OH to the other C, and so can be considered as the hydrate of ethene.  A molecule of water may be eliminated, for example, by the action of [[sulfuric acid]]. Another example is [[chloral hydrate]], {{chem2|CCl3\sCH(OH)2}}, which can be formed by reaction of water with [[chloral]], {{chem2|CCl3\sCH\dO}}.

Many organic molecules, as well as inorganic molecules, form crystals that incorporate water into the crystalline structure without chemical alteration of the organic molecule ([[water of crystallization]]). The sugar [[trehalose]], for example, exists in both an [[anhydrous]] form ([[melting point]] 203&nbsp;°C) and as a dihydrate (melting point 97&nbsp;°C). [[Protein crystallization|Protein crystals]] commonly have as much as 50% water content.

Molecules are also labeled as hydrates for historical reasons not covered above. [[Glucose]], {{chem2|C6H12O6}}, was originally thought of as {{chem2|C6(H2O)6}} and described as a [[carbohydrate]].

Hydrate formation is common for [[active ingredient]]s. Many manufacturing processes provide an opportunity for hydrates to form and the state of hydration can be changed with environmental humidity and time. The state of hydration of an active pharmaceutical ingredient can significantly affect the solubility and dissolution rate and therefore its [[bioavailability]].<ref>Surov, Artem O., Nikita A. Vasilev, Andrei V. Churakov, Julia Stroh, Franziska Emmerling, and German L. Perlovich. "Solid Forms of Ciprofloxacin Salicylate: Polymorphism, Formation Pathways and Thermodynamic Stability". Crystal Growth & Design (2019). {{doi|10.1021/acs.cgd.9b00185}}.</ref>