Methanediol, also known as formaldehyde monohydrate or methylene glycol, is an organic compound with chemical formula CH2(OH)2. It is the simplest geminal diol. It is not encountered in pure form, but as aqueous solutions, where it coexists with oligomers (short polymers). The compound is well characterized but of less technological significance than related paraformaldehyde ((CH2O)n), formaldehyde (H2C=O), and trioxane ((CH2O)3).
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||48.041 g·mol−1|
|Density||1.199 g cm−3|
|Boiling point||194 °C (381 °F; 467 K) at 101 kPa|
|Vapor pressure||16.1 Pa|
Refractive index (nD)
|Flash point||99.753 °C (211.555 °F; 372.903 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Methanediol is a product of the hydration of formaldehyde. The equilibrium constant for hydration is estimated to be 103, CH2(OH)2 predominates in dilute (<0.1%) solution. In more concentrated solutions, it oligomerizes to HO(CH2O)nH.
The dianion, methanediolate, is believed to be an intermediate in the crossed Cannizzaro reaction.
Methanediol, rather than formaldehyde, is listed as one of the main ingredients of "Brazilian blowout", a hair-straightening formula marketed in the US. The equilibrium with formaldehyde has caused concern since formaldehyde in hair straighteners is a health hazard, but the risk has been disputed.
- "Methanediol - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. Retrieved 20 October 2011.
- Bell, R. P.; McTigue, P. T. (1960). "603. Kinetics of the aldol condensation of acetaldehyde". Journal of the Chemical Society (Resumed): 2983. doi:10.1039/JR9600002983.
- Reuss, Günther; Disteldorf, Walter; Gamer, Armin Otto; Hilt, Albrecht (2000). "Formaldehyde". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_619.
- Eric V. Anslyn, Dennis A. Dougherty (2006), Modern physical organic chemistry. University Science Books. ISBN 1-891389-31-9. 1095 pages
- Garrod, Robin T.; Weaver, Susanna L. Widicus; Herbst, Eric (2008). "Complex Chemistry in Star‐forming Regions: An Expanded Gas‐Grain Warm‐up Chemical Model". The Astrophysical Journal. 682 (1): 283–302. arXiv:0803.1214. Bibcode:2008ApJ...682..283G. doi:10.1086/588035.
- "Hair Smoothing Products That Could Release Formaldehyde". www.osha.gov. Occupational Safety and Health Administration.
- SpecialChem. "Industry News".
- Golden, R.; Valentini, M. (July 2014). "Formaldehyde and methylene glycol equivalence: Critical assessment of chemical and toxicological aspects". Regulatory Toxicology and Pharmacology. 69 (2): 178–186. doi:10.1016/j.yrtph.2014.03.007. PMID 24709515.