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Chemical compound From Wikipedia, the free encyclopedia
2-Methyl-2,4-pentanediol (MPD) is an organic compound with the formula (CH3)2C(OH)CH2CH(OH)CH3. This colourless liquid is a chiral diol. It is produced industrially from diacetone alcohol by hydrogenation.[4] Total European and USA production was 15000 tonnes in 2000.[5]
Names | |
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Preferred IUPAC name
2-Methylpentane-2,4-diol | |
Other names
2-Methyl-2,4-pentanediol Hexylene glycol Diolane 1,1,3-Trimethyltrimethylenediol 2,4-Dihydroxy-2-methylpentane Isol | |
Identifiers | |
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3D model (JSmol) |
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Abbreviations | MPD |
1098298 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.003.173 |
EC Number |
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PubChem CID |
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RTECS number |
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UNII | |
UN number | 1993 |
CompTox Dashboard (EPA) |
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Properties | |
C6H14O2 | |
Molar mass | 118.176 g·mol−1 |
Appearance | colourless liquid |
Odor | mild, sweetish[1] |
Density | 0.92 g/mL |
Melting point | −40 °C (−40 °F; 233 K) |
Boiling point | 197 °C (387 °F; 470 K) |
miscible[1] | |
Vapor pressure | 0.05 mmHg (20°C)[1] |
Hazards | |
GHS labelling:[2] | |
Warning | |
H315, H319 | |
P264, P264+P265, P280, P302+P352, P305+P351+P338, P321, P332+P317, P337+P317, P362+P364 | |
Flash point | 98.3 °C (208.9 °F; 371.4 K)[3] |
Explosive limits | 1.3%-7.4%[1] |
NIOSH (US health exposure limits): | |
PEL (Permissible) |
none[1] |
REL (Recommended) |
C 25 ppm (125 mg/m3)[1] |
IDLH (Immediate danger) |
N.D.[1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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2-Methyl-2,4-pentanediol exists as two enantiomers, (4R)-(−) and (4S)-(+). In the Protein Data Bank, the 3-letter code "MPD" refers to the (S)-(−) enantiomer, while "MRD" is used to refer to the (R)-(+) version. Commercial products labeled "MPD" are usually the racemate,[6] also sold as and referred to as "hexylene glycol".[7][8]
2-Methyl-2,4-pentanediol exhibits both surfactant and emulsion-stabilizing properties. Its relatively high viscosity and low volatility are advantageous in coatings, cleansers, cosmetics, solvents, lubricants, and hydraulic fluids.[9] Although it is an irritant at higher concentrations, it is sometimes used in skin care, hair care, soap, and eye cosmetic products at concentrations ranging from 0.1% - 25%.[10][11]
It is biodegradable and unlikely to accumulate in the environment.[12]
In the laboratory it is a common precipitant and cryoprotectant in protein crystallography.[13] Since hexylene glycol is compatible with polar and nonpolar molecules, it competes with the solvent in a crystallography experiment causing the protein to precipitate.[14] Hexylene glycol is so effective in protein crystallography because its amphiphilic nature and small, flexible structure allows it to bind to many different locations on a protein secondary structure including alpha helices and beta sheets.[15] When hexylene glycol binds to these different locations, water is removed and the protein crystals anneal, which prevents ice formation during cryocrystallography techniques.[16] Incorporation of hexylene glycol into solution has been known to improve the resolution of X-ray diffraction making protein structures easily identifiable.[17] Additionally hexylene glycol is not a strong denaturing agent and thus does not significantly alter the structure of a protein during the crystallography procedure.[15]
Hexylene glycol is also used as a lubricant for polishing specimens in metallography.[18]
Like related diols, it forms borate esters.
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