Dimethyl aprotic, polar

The preparation of fluoroaromatics by the reaction of KF with perhaloaromatics, primarily hexachloroben2ene, has received considerable attention. Two methods were developed and include either the use of an aprotic, polar solvent, such as /V-methy1pyrro1idinone (8), or no solvent (9). These methods plus findings that various fluoroaryl derivatives are effective fungicides (10) prompted development of a commercial process for the production of polyfluoroben2enes (11). The process uses a mixture of sodium and potassium fluorides or potassium fluoride alone in aprotic, polar solvents such as dimethyl sulfoxide or sulfolane. 

Aromatic nucleophilic radiofluorinations are usually performed in aprotic polar solvents, such as dimethyl sulfoxide (DMSO), sulfolane or dimethylacetamide, and often under basic conditions (because of the presence of Kryptofix-222 / potassium carbonate). Completion of the p F]fluoride incorporation often requires moderate to high temperatures (100-170 °C) for 10-30 min. Microwave technology can be a successful application here, resulting in improved yields and shorter reaction times [29,170-173],... 

Dimethyl-sulfoxide (DMSO) is an aprotic polar solvent often used in organic chemical synthesis. It is known for its limited thermal stability so usually precautions are taken to avoid its exothermal decomposition. The decomposition energy is approximately 500 J g 1, which corresponds to an adiabatic temperature rise of over 250 K. 

Solvent/nonsolvent system. The solvent must be miscible with the nonsolvent (here an aqueous system). An aprotic polar solvent like N-methyl pyrrolidone (NMP), dimethyl formamide (DMF), dimethyl acetamide (DMAc) or dimethylsulfoxide (DMSO) is preferable for rapid precipitation (instantaneous demixing) upon immersion in the nonsolvent water. As a consequence, a high porosity anisotropic... 

Later, other cellulose solvents were developed, like the N-methylmorpholine-N -oxide (NMMO) in water, systems of lithium chloride with an aprotic polar solvent, dimethyl acetamide, dimethyl formamide and dimethyl sulfoxide, but again, only the former has been successful and led to the LYOCELL fibre. 

Fortunately, radicals are a neutral species in general. Thus, they are not affected by the various kinds of solvents (reaction media), i.e. protic polar solvents such as ethanol and water, aprotic polar solvents such as acetonitrile, dimethyl sulfoxide, and non-polar solvents such as hexane and benzene. Moreover, radicals are not affected fundamentally by basic species or acidic species. Radical reactions should take place not only in benzene, but also in water, and proceed not only in 1 N aqueous HC1 solution, but also in 1 N aqueous NaOH solution. This is the fundamental character of radicals and radical reactions, and is a great advantage an advantage that should be reflected in green chemistry. 

Alkynylsilanes can be converted into alkynylcoppers by treatment with Cu salts in an aprotic polar solvent such as l,3-dimethyl-2-imidazolidinone (DMI).62 The Cu-promoted coupling reactions via the Si-Cu transmetallation of alkynylsilanes are valuable for the syntheses of alkynyl ketones, 1,3-diynes, 1,3-enynes, and 1-aryl-l-alkynes from acid chlorides,62 alkynyl chlorides,63 alkenyl iodides,64 and aryl iodides,64 respectively (Equation (12)). In addition, symmetric 1,3-diynes can be prepared by the CuCl-mediated homocoupling of alkynylsilanes.65 653... 

Aprotic polar liquids such as dimethyl sulfoxide and acetonitrile make up another group. These molecules have high dipole moments, so that dipole-dipole interactions are an important part of the description of intermolecular forces. 

In considering the solvation of charged species by a polar solvent, the polar solvents we considered were hydrogen bond donors (protic polar solvents) such as water and alcohols. Some polar solvents—for example, Ai,77-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and hexamethylphosphoric acid triamide (HMPA)—are not hydrogen bond donors (they are aprotic polar solvents) (Table 10.7). 

Polyimides can be prepared through several step-growth processes. One of the most common methods used for this purpose is the reaction of dianhydrides with diamines (Fig. 3.6). The first product obtained is poly(amic acid), which has the advantage of being soluble in organic solvents (normally aprotic polar solvents are used, such as dimethyl sulfoxide, DMF, dimethylacetamide, and NMP). The solution of poly(amic acid) can easily be manipulated or processed. The acid can then be cycled thermally, generating the polyamide, which is insoluble in most of the common organic solvents. 

Certain aprotic polar solvents, including dimethylformamide, dimethyl sulfoxide, and hexamethylphosphoramide, have been found to markedly accelerate enolate alkylation reactions. The relative rates of alkylation of the sodium enolate of diethyl n-butylmalonate by butyl bromide are shown in Table 1.3. The greatly enhanced rates in dimethylformamide and dimethyl sulfoxide illustrate the rate enhancement by polar aprotic solvents. 

Diethyl malonate stirred 1 hr. with NaH in dimethyl sulfoxide as aprotic polar solvent, then a soln. of 9-nitroanthracene in warm dimethyl sulfoxide added,... 

Chloro-ll,12-cz5-dichloro-9,10-dihydro-9,10-ethanoanthracene and activated Zn-dust in dimethyl sulfoxide as aprotic polar solvent stirred and heated 12 days at 80° -> 2-chlorodibenzobarrelene. Y 92%. F. e. s. H. P. Figeys and A. Dra-lantis, Tetrahedron 28, 3031 (1972) from 1,2-dibromides with Na- thiosulfate in dimethyl sulfoxide s. K. M. Ibne-Rasa, A. R. Tahir, and A. Rahman, Chem. Ind. 1973, 232. 

The dimethyl ethers of oligoethylene glycols (glymes) have long been known to enhance the reactivities of soluble metal salts. For example, in 1960 Zaugg and coworkers described the rate enhancement of sodiomalonate ester alkylation in benzene solution by glymes and a large number of other aprotic, polar additives. 

Intravascular catheter is used for providing central venous nutrition and performing dialysis treatment. Antimicrobial layers may be formed with an antimicrobial agent such as antibiotic coated on the surface. The antimicrobial agent may be continually released from the surface while inside the body. Most antibiotics are very polar and do not dissolve in organic solvents. Aprotic polar solvents, such as dimethylformamide, dimethyl sulfoxide, dimethylacetamide, 2-butanone, acetone, acetinitrile, and N-metiiylpyrrolidone are useful in this application. ... 

The polymerizations require the use of dipolar aprotic solvents such as N-methylpyrrolidone (NMP), dimethyl acetamide (DMAC), dimethyl sulfoxide (DMSO) or N,N -dimethylpropylene urea (DMPU). Nucleophilic aromatic substitution polymerizations are t q>ically performed in a high boiling aprotic polar solvent with the monomer(s) reacted in the presence of a base, potassium carbonate, at elevated temperatures (ca. 180 C). Potassium carbonate is used to convert the phenol into the potassium phenolate and since K2CO3 is a weak base, no hydrolytic side reactions are observed. Dipolar aprotic solvents are used in these poly(aryl ether) syntheses, since they effectively dissolve the monomers and solvate the polar intermediates and the final polymer. DMPU has been shown to be an excellent solvent for poly(ether) syntheses, particularly for those polymers which are only marginally soluble in other dipolar aprotic solvents (22). Furthermore, DMPU allows higher reaction temperatures (260 C). We have observed that DMPU, when used in conjunction with toluene as a dehydrating agent, accelerates many nucleophilic substitution reactions. 

Sulfur-containing Dimethyl sulfoxide Polar aprotic 18.2 6.3 6.1 20.3 P... 

Solvent for Displacement Reactions. As the most polar of the common aprotic solvents, DMSO is a favored solvent for displacement reactions because of its high dielectric constant and because anions are less solvated in it (87). Rates for these reactions are sometimes a thousand times faster in DMSO than in alcohols. Suitable nucleophiles include acetyUde ion, alkoxide ion, hydroxide ion, azide ion, carbanions, carboxylate ions, cyanide ion, hahde ions, mercaptide ions, phenoxide ions, nitrite ions, and thiocyanate ions (31). Rates of displacement by amides or amines are also greater in DMSO than in alcohol or aqueous solutions. Dimethyl sulfoxide is used as the reaction solvent in the manufacture of high performance, polyaryl ether polymers by reaction of bis(4,4 -chlorophenyl) sulfone with the disodium salts of dihydroxyphenols, eg, bisphenol A or 4,4 -sulfonylbisphenol (88). These and related reactions are made more economical by efficient recycling of DMSO (89). Nucleophilic displacement of activated aromatic nitro groups with aryloxy anion in DMSO is a versatile and useful reaction for the synthesis of aromatic ethers and polyethers (90). 

It is prepared from the polycondensation of the disodium salt of bisphenol A and 4,4-dichlorodiphenyl sulfone in a polar aprotic solvent such as dimethyl sulfoxide (26). 

Dimethyl sulfoxide (DMSO) is a particularly well-known sulfoxide that is often used as a polar aprotic solvent. It must be handled with care, however, because it has a remarkable ability to penetrate the skin, carrying along whatever is dissolved in it. 

Polar aprotic solvent (Section 11.3) A polar solvent that can t function as a hydrogen ion donor. Polar aprotic solvents such as dimethyl sulfoxide (DMSO) and dimethyl-formamide (DMF) are particularly useful in Sn2 reactions because of their ability to solvate cations. 

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