Dimethyl tetramethylurea

Cl Vat Blue 4 is prepared from 2-arniaoaiitliraquiQoiie (66) by potash fusion in the presence of an oxidising agent such as sodium nitrite or air. An alternative method by dimerization of 1-aminoanthraquinone (17) by using such solvents as dimethyl sulfoxide or tetramethylurea has been reported, and improved methods for this reaction have been cited (135—138). These methods are considered to be advantageous in terms of the yield as well as the availability of starting compounds. 

NMR has been used to study ligand exchange in non-coordinating solvents for a series of Be(C104)2-4L (L = trimethyl phosphate, DMSO, DMA, DMF, NMA, 1,1,3,3-tetramethylurea, dimethyl methylphosphonate and dimethyl phenylphosphonate) complexes. 3H NMR studies show that the mode of activation for exchange on beryllium varies from dissociative to associative depending upon L and the nature of the non-coordinating solvent.127 128... 

Walash and Rizk (32) reported a non-aqueous titration of several analgesics in dosage form including salicylamide in tetramethylurea using 0.1 N sodium methoxide as the titrant, the end point was measured either potentio-metrically or with thymol blue as indicator. The results were comparable with those obtained using dimethyl-formamide as a solvent. 

TMU = tetramethylurea, DMF = dimethylformamide, DMA = dimethylacetamide, NMPo -N-methyl-2-pyrrolidone, DMSO = dimethyl sulfoxide, HMPA = hexamethy phosphoric triamide... 

In contrast, dipolar aprotic solvents possess large relative permittivities (sr > 15), sizeable dipole moments p > 8.3 10 ° Cm = 2.5 D), and average C.f values of 0.3 to 0.5. These solvents do not act as hydrogen-bond donors since their C—H bonds are not sufficiently polarized. However, they are usually good EPD solvents and hence cation sol-vators due to the presence of lone electron pairs. Among the most important dipolar aprotic solvents are acetone, acetonitrile [75], benzonitrile, A,A-dimethylacetamide [76, 77], A,A-dimethylformamide [76-78], dimethylsulfone [79], dimethyl sulfoxide [80-84], hex-amethylphosphoric triamide [85], 1-methylpyrrolidin-2-one [86], nitrobenzene, nitro-methane [87], cyclic carbonates such as propylene carbonate (4-methyl-l,3-dioxol-2-one) [88], sulfolane (tetrahydrothiophene-1,1-dioxide) [89, 90, 90a], 1,1,3,3-tetramethylurea [91, 91a] and tetrasubstituted cyclic ureas such as 3,4,5,6-tetrahydro-l,3-dimethyl-pyr-imidin-2-(l//)-one (dimethyl propylene urea, DMPU) [133]. The latter is a suitable substitute for the carcinogenic hexamethylphosphoric triamide cf. Table A-14) [134]. 

Abbreviations Ac acetyl Bn benzyl BSP 1-benzenesulfinyl piperidine BTIB bis(trifluoroacetoxy)iodobenzene DAST (diethylamino)sulfur trifluoride DDQ 2,3-dichloro-5,6-dicyano-/)-benzoquinone DMDO dimethyldioxirane DMTSF dimethyl(methylthio)sulfonium tetrafluoroborate DMTST dimethyl(methylthio)sulfonium triflate DTBMP 2,6-Ai-tert-butyl-4-methylpyridine DTBP 2,6-di-tert-butylpyridine DTBPl 2,6-di-tert-butylpyridinium iodide FDCPT l-fluoro-2,6-dichloropyridinium triflate FTMPT l-fluoro-2,4,6-trimethylpyridinium triflate IDCP iodonium dicollidine perchlorate IDCT idonium dicollidine triflate LPTS 2,6-lutidinium p-toluenesulfonate LTMP lithium tetramethylpiperidide Me methyl MPBT S-(4-methoxyphenyl) benzenethiosulflnate NBS A-bromosuccinimide NIS A-iodosuccinimide NlSac A-iodosaccharin PPTS pyridinium p-toluenesulfonate TBPA tris(4-bromophenyl)ammoniumyl hexachloroantimonate Tf trifluoromethanesulfonyl TMTSB methyl-bis(methylthio)sulfonium hexachloroantimonate TMU tetramethylurea Tr trityl TTBP 2,4,6-tri-tert-butylpyrimidine. 

C-Alkylation Diethyl sulfate. Dimethyl sulfate. Dimethyl sulfoxide reagent (a). Methyl bromide. Methyl chloride. Nitrosonium hexafluorophosphate. Potassium r-butoxide. Sodium amide, Sodium ethoxide. Sodium 2-methyl-2-butoxide. Tetramethylurea. Tri-ethyloxonlum fluuruburate. Trimcthyloxonium fluurubomte. Trimethyloxonium 2,4,6-trlnltrobenzene lulfonale. Triiyliodium. 

Various other novel PT catalysts have been developed which find specific applications in certain types of reactions. For example, Kondo et al. (1988, 1989, 1994, and references therein) have been developed polymeric analogs of dipolar aprotic solvents like dimethyl sulfoxide, V-V-dimethylfor-mamide, N-methyl-2-pyrrohdone, tetramethylurea, and so on in both soluble and immobilized forms. Similarljcjiiral PT... 

Muetterties (376) reports that ethers and sulfones do not react with zirconium tetrafluoride at 50°-160°C, whereas 2 1 adducts of dimethyl sulfoxide, A,A -tetramethylurea, and dimethylformamide were formed upon refluxing a slurry of the tetrafluoride in excess base. The soluble... 

Lr. and n.m.r. spectra of HDO and of MeOH, at low concentration in MeCN, propylene carbonate, 1,1,3,3-tetramethylurea, and NN-dimethyl-formamide containing various salts [LiC104, LiBr, Sr(CI04)2, Ca(SCN)2], have been determined at 308 2 K. The results suggest the presence of solvent-bonded, cation-bonded, anion-bonded, and solvent-shared or solvent-separated ion complexes. ... 

Hexanediol 1.2- Pentanediol 2-Pyrrolidone N-Methyl-2-pyrrolidone N,N -Dimethylpropyleneurea l,3-Dimethyl-2-imidazolidinone Tetramethylurea Dimethylsulfoxide Hexamethylphosphoric triamide Propylene glycol 1,3-Propanediol... 

Sj 2 reactions are greatly aided by dipolar aprotic solvents such as DMSO, DMF, HMPA, tetramethylurea, or l,3-dimethyl-2-imidazolidinone. In these solvents, the positive end of the dipole is relatively encumbered while the negative end is exposed and available for association with cations. The anions are thus not well solvated and exceptionally reactive. For example, NaCN in DMSO reacts with primary and secondary alkyl... 

For solubility reasons, the SbCls complexation could not be accomplished in a less polar solvent. For example, the complexes of the following bases were not soluble enough in CCI4 dimethyl sulfoxide, dimethylacetamide, tetramethylurea, trihexylamine and octylamine... 

Calorimetric (enthalpy), i.r. (OH frequency shift), and n.m.r. (hydrogen-bond chemical shift) data have been reported for the interaction of 1,1,1,3,3,3-hexafluoropropan-2-ol with a series of Lewis bases (nitrogen and oxygen donors and the soft donor diethyl sulphide), and details of studies on the 1 1 and 2 1 complexes formed between this highly acidic alcohol [pJira(H20) 9 3] and dimethyl sulphoxide, tetramethylurea, tetramethylene sulphone, and 1,4-dioxan have become available. Hydrogen bonding between water vapour (the acceptor) and l,l,l,3,3,3-hexafluoropropan-2-ol has been detected by i.r. spectroscopy. ... 

So far, no crystallographic evidence for adducts of silanes with aldehydes, ketones, esters, or acyl halides has been reported [81]. Dimethylformamide [86-88] and tetramethylurea [89], however, are known to enter the silicon coordination sphere (e.g., in 13 and 14, respectively). In a similar manner amine-M-oxides (e.g., in 15) [90], phosphine oxides (e.g., in 16 and 17) [90,91], and phosphoric amides [92-94] form hypercoordinated Si complexes. Although dimethyl sulfoxide (DMSO) increases the silicon coordination number (as shown Si NMR spectroscopy) [49], crystallographic evidence for a siUcmi complex with DMSO Ugand(s) is still lacking [81]. 

Deoxygenation of Epoxides. Fe(CO)5 in MA -dimethyl-acetamide or tetramethylurea deoxygenates epoxides (2 h, 145 °C). The reaction is not stereospecific franj-stilbene oxide is converted into both trans- (56%) and cw-stilbene (22%). Epoxides of 1-alkenes are converted mainly into mixtures of internal alkenes. 

V-methylpyrrolidone (NMP) (Elashmawi 2008), dimethyl sulfoxide (DMSO), hexa-methylphosphoramide (HMPA), tetramethylurea (TMU), trimethyl phosphate (TMP), and TEP (Bottino et al. 1991 Lin et al. 2006b Shi et al. 2008). In addition, combinations of these solvents are also employed, such as TMP-DMA, TEP-DMA, tricresyl phosphate-DMA and tri- -butyl phosphate-DMA (Li et al. 2010). 

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