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Names | |
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Preferred IUPAC name Tetramethylurea | |
Other names 1,1,3,3-Tetramethylurea | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.010.159 |
EC Number |
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PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C5H12N2O | |
Molar mass | 116.164 g·mol−1 |
Appearance | Colorless liquid |
Density | 0.968 g/mL |
Melting point | −1.2 °C (29.8 °F; 271.9 K) |
Boiling point | 176.5 °C (349.7 °F; 449.6 K) |
Hazards | |
GHS labelling: | |
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Danger | |
H302, H360, H361 | |
P201, P202, P264, P270, P281, P301+P312, P308+P313, P330, P405, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Tetramethylurea (TMU) is the organic compound with the formula (Me2N)2CO. It is a substituted urea. This colorless liquid is used as an aprotic-polar solvent, especially for aromatic compounds and is used e. g. for Grignard reagents. [1] Tetramethylurea is a colorless liquid with mild aromatic odor. [2] Unusual for an urea is the liquid state of tetramethylurea in a range of > 170 °C.
It is obtained by the reaction of dimethylamine with phosgene in the presence of sodium hydroxide solution. [3] A closely related method combines dimethylcarbamoyl chloride with excess dimethylamine. [4] [5] This reactions is highly exothermic. The removal of the resulting dimethylamine hydrochloride requires some effort. [1]
The reaction of diphenylcarbonate with dimethylamine in an autoclave is also effective.
Tetramethylurea is formed upon the oxygenation of tetrakis(dimethylamino)ethylene (TDAE). [6]
Tetramethylurea is also a common by-product formed in amide bond forming reactions and peptide synthesis with uronium and guanidinium-based reagents such as HATU, HBTU and TCFH.
Tetramethylurea is miscible with a variety of organic compounds, including acids such as acetic acid or bases such as pyridine and an excellent solvent for organic substances such as ε-caprolactam and benzoic acid. It dissolves even some inorganic salts such as silver nitrate and sodium iodide. [7] [8] Tetramethylurea is often used in place of hexamethylphosphoramide (HMPT), which is suspected of being carcinogenic. [9]
Tetramethylurea is suitable as a reaction medium for the polymerization of aromatic diacid chlorides (such as isophthalic acid) and aromatic diamines (such as 1,3-diaminobenzene (m-phenylenediamine)) to aramids such as poly (m-phenylene isophthalamide) (Nomex®) [10] [11]
The polymerization of 4-amino benzoic acid chloride hydrochloride in tetramethylurea provides isotropic viscous solutions of poly(p-benzamide) (PPB), which can be directly spun into fibers. [12]
In a tetramethylurea-LiCl mixture stable isotropic solutions can be obtained up to a PPB polymer concentration of 14%. [13]
Tetramethylurea also dissolves cellulose ester and swells other polymers such as polycarbonates, polyvinyl chloride or aliphatic polyamides, usually at elevated temperature. [1]
Strong and hindered non-nucleophilic guanidine bases are accessible from tetramethylurea in a simple manner, [14] [15] which are in contrast to the fused amidine bases DBN or DBU not alkylated.
A modification of the Koenigs-Knorr reaction for building glycosides from 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide (acetobromoglucose) originates from S. Hanessian who used the silver salt silver trifluoromethanesulfonate (TfOAg) and as a proton acceptor tetramethylurea. [16] This process variant is characterized by a simplified process control, high anomeric purity and high yields of the products. If the reaction is carried out with acetobromoglucose and silver triflate/tetramethylurea at room temperature, then tetramethylurea reacts not only as a base, but also with the glycosyl to form a good isolable uroniumtriflates in 56% yield. [17]
The acute toxicity of tetramethylurea is moderate. However, it is embryotoxic and teratogenic towards several animal species. [18] Tetramethylurea was demonstrated to not exhibit dermal corrosion but did exhibit dermal and eye irritation. [19] The sensitization potential of tetramethylurea was shown to be low compared (non-sensitizing at 1% in LLNA testing according to OECD 429 [20] ).