Methylpropanediol (2-Methyl-1,3-propanediol) is a chemical organic compound, with low molecular weight, a low viscosity liquid glycol.

The name describes the structure of the molecule:

• Methyl. Indicates the presence of a methyl group (-CH₃) in the molecule.
• Propane. A three-carbon chain (propane).
• Diol.  This suffix indicates the presence of two hydroxyl groups (-OH) in the molecule.

The main raw materials used in the production of methylpropanediol are:

• Propylene Oxide is a key raw material in the synthesis of methylpropanediol. It is an organic compound that is used as a starting material for various chemical reactions, including the production of diols like methylpropanediol.
• Methanol or Isobutylene are the other important raw materials used in the synthesis of methylpropanediol. These compounds react with propylene oxide in the presence of suitable catalysts to form methylpropanediol.

The synthesis process takes place in different steps:

• Production of hydroxyacetone, a chemical compound also known as acetone, which is a key intermediate in the production of methylpropanediol. It can be produced by different methods, including the oxidation of propylene glycol or the hydration of acetone.
• Hydrogenation of hydroxyacetone which is reacted with hydrogen in the presence of a catalyst in a process known as hydrogenation. This reaction converts hydroxyacetone to methylpropanediol.
• Purification. In the final step, unreacted materials and by-products are removed from the reaction mixture to obtain pure methylpropanediol. This is followed by a series of distillation, filtration and centrifugation steps.

It appears as a clear, colourless, odourless, moderately viscous liquid.

What it is used for and where

Cosmetics

• Solvent. It is the substance for dissolving or dispersing in solution, surfactants, oils, dyes, flavors, bacterial preservatives. Solvents generally occur in liquid, aqueous and nonaqueous forms.

It is also used as a humectant and emulsifier for final applications of personal care products.

Industry

It can be used to produce polyester plasticizer, liquid saturated polyester, unsaturated polyester, thermoplastic polyester resin (modification of PET and PBT), alkyd resin, polyurethane resin.

It is used in the production of polyurethane coatings, low crystallinity polyester polyols and can be used as chain extender, adhesives, sealants or elastomers needed to maintain transparency, long stability and weather resistance.

Safety

No carcinogenicity studies have been identified with Methylpropanediol, which presents a low degree of toxicological and ecotoxicological or environmental risk (1).

Methylpropanediol studies

Typical commercial product characteristics 2-Methyl-1,3-propanediol

Appearance	Clear colourless liquid
pH	6~8
Water	0.08% max
Boiling point	123-125ºC (20 mmHg)
Melting Point	−91°C
Flash Point	127°C   >230 °F
Density	1.015 g/mL at 25 °C
Refractive index	n20/D 1.445(lit.)
Auto-ignition temperature	380℃
Index of Refraction	1.438
Vapour density	3.2 (vs air)
Vapour Pressure	0.0±0.9 mmHg at 25°C
Vapor Density	3.2（60~90℉）(air=1)
Relative density	(H2O=1): 1.01 @39.2℉
n-octanol/water	(log Kow): -0.6
Iron ppm	0.5 max
Carbonyl ppm	500 max
Safety

• Molecular Formula  C₄H₁₀O₂
• Linear Formula   CH₃CH(CH₂OH)₂
• Molecular Weight     90.12
• Exact Mass   90.068077
• CAS  2163-42-0
• UNII    N8F53B3R4R
• EC Number   412-350-5
• DSSTox Substance ID  
• IUPAC  2-methylpropane-1,3-diol
• InChI=1S/C4H10O2/c1-4(2-5)3-6/h4-6H,2-3H2,1H3 
• InChl Key      QWGRWMMWNDWRQN-UHFFFAOYSA-N
• SMILES   CC(CO)CO
• MDL number  MFCD00082586
• PubChem Substance ID    24863400
• Beilstein   1731422
• NACRES NA.23

Synonyms:

• 2-Methylpropane-1,3-diol
• Propane-1,3-diol, 2-methyl-
• 1,3-Propanediol, 2-methyl-methylpropanediol
• 1,3-Dihydroxy-2-methylpropane

References______________________________________________________________

(1) Fowles J, Lewis C, Rushton E. Studies on the environmental fate, ecotoxicology and toxicology of 2-methyl 1,3-propanediol. Regul Toxicol Pharmacol. 2017 Dec;91:240-248. doi: 10.1016/j.yrtph.2017.10.031.