A polar aprotic solvent is a solvent that lacks an acidic proton and is polar. Such solvents lack hydroxyl and amine groups. In contrast to protic solvents, these solvents do not serve as proton donors in hydrogen bonding, although they can be proton acceptors. Many solvents, including chlorocarbons and hydrocarbons, are classifiable as aprotic, but polar aprotic solvents are of particular interest for their ability to dissolve salts. [1] [2] Methods for purification of common solvents are available. [3]
Solvent | Chemical formula | Boiling point | Dielectric constant | Density | Dipole moment (D) | Comment |
---|---|---|---|---|---|---|
Polar aprotic solvents | ||||||
acetone | (CH3)2CO | 56.1 °C | 21.8 | 0.785 g/cm3 | 2.91 | reacts with strong acids and bases |
acetonitrile | CH3CN | 82 °C | 38.3 | 0.776 g/cm3 | 3.20 | reacts with strong acids and bases |
dichloromethane | CH2Cl2 | 39.6 °C | 9.08 | 1.327 g/cm3 | 1.6 | low boiling point |
dimethylacetamide | (CH3)2NCOCH3 | 165 °C | 37.8 | 0.94 g/cm3 | 3.72 | reacts with strong acids and bases |
dimethylformamide | (CH3)2NCHO | 153 °C | 36.7 | 0.95 g/cm3 | 3.86 | reacts with strong acids and bases |
N-methylpyrrolidone | CH3NCOC3H6 | 203 °C | 32.3 | 1.028 g/cm3 | 4.09 | high boiling point |
dimethylimidazolidone | (CH3N)2COC2H4 | 225 °C | 37.6 | 1.056 g/cm3 | 4.09 | high boiling point |
dimethylpropyleneurea | (CH3N)2COC3H6 | 246.5 °C | 36.1 | 1.064 g/cm3 | 4.23 | high boiling point |
dimethyl sulfoxide | (CH3)2SO | 189 °C | 46.7 | 1.10 g/cm3 | 3.96 | reacts with strong bases, difficult to purify |
ethyl acetate | C2H5OCOCH3 | 77.1°C | 6.02 | 0.902 g/cm3 | 1.88 | reacts with strong bases |
hexamethylphosphoramide | [(CH3)2N]3PO | 232.5 °C | 29.6 | 1.03 g/cm3 | 5.38 | high boiling point, high toxicity |
propylene carbonate | CH3C2H3O2CO | 242 °C | 64.9 | 1.205 g/cm3 | 4.94 | high boiling point |
pyridine | C5H5N | 115 °C | 13.3 | 0.982 g/cm3 | 2.22 | reacts with protic and Lewis acids |
sulfolane | C4H8SO2 | 286 °C | 43.3 | 1.27 g/cm3 | 4.8 | high boiling point |
tetrahydrofuran | C4H8O | 66 °C | 7.6 | 0.887 g/cm3 | 1.75 | polymerizes in presence of strong protic and Lewis acids |
A solvent is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar molecules, and the most common solvent used by living things; all the ions and proteins in a cell are dissolved in water within the cell.
Acetonitrile, often abbreviated MeCN, is the chemical compound with the formula CH3CN and structure H3C−C≡N. This colourless liquid is the simplest organic nitrile. It is produced mainly as a byproduct of acrylonitrile manufacture. It is used as a polar aprotic solvent in organic synthesis and in the purification of butadiene. The N≡C−C skeleton is linear with a short C≡N distance of 1.16 Å.
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water-miscible organic liquid with low viscosity. It is mainly used as a precursor to polymers. Being polar and having a wide liquid range, THF is a versatile solvent. It is an isomer of another solvent, butanone.
Nitromethane, sometimes shortened to simply "nitro", is an organic compound with the chemical formula CH
3NO
2. It is the simplest organic nitro compound. It is a polar liquid commonly used as a solvent in a variety of industrial applications such as in extractions, as a reaction medium, and as a cleaning solvent. As an intermediate in organic synthesis, it is used widely in the manufacture of pesticides, explosives, fibers, and coatings. Nitromethane is used as a fuel additive in various motorsports and hobbies, e.g. Top Fuel drag racing and miniature internal combustion engines in radio control, control line and free flight model aircraft.
In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.
Acetamide (systematic name: ethanamide) is an organic compound with the formula CH3CONH2. It is an amide derived from ammonia and acetic acid. It finds some use as a plasticizer and as an industrial solvent. The related compound N,N-dimethylacetamide (DMA) is more widely used, but it is not prepared from acetamide. Acetamide can be considered an intermediate between acetone, which has two methyl (CH3) groups either side of the carbonyl (CO), and urea which has two amide (NH2) groups in those locations. Acetamide is also a naturally occurring mineral with the IMA symbol: Ace.
Lithium diisopropylamide is a chemical compound with the molecular formula LiN(CH 2)2. It is used as a strong base and has been widely utilized due to its good solubility in non-polar organic solvents and non-nucleophilic nature. It is a colorless solid, but is usually generated and observed only in solution. It was first prepared by Hamell and Levine in 1950 along with several other hindered lithium diorganylamides to effect the deprotonation of esters at the α position without attack of the carbonyl group.
Dimethylformamide, DMF is an organic compound with the chemical formula HCON(CH3)2. Its structure is HC(=O)−N(−CH3)2. Commonly abbreviated as DMF, this colourless liquid is miscible with water and the majority of organic liquids. DMF is a common solvent for chemical reactions. Dimethylformamide is odorless, but technical-grade or degraded samples often have a fishy smell due to impurity of dimethylamine. Dimethylamine degradation impurities can be removed by sparging samples with an inert gas such as argon or by sonicating the samples under reduced pressure. As its name indicates, it is structurally related to formamide, having two methyl groups in the place of the two hydrogens. DMF is a polar (hydrophilic) aprotic solvent with a high boiling point. It facilitates reactions that follow polar mechanisms, such as SN2 reactions.
Dimethoxyethane, also known as glyme, monoglyme, dimethyl glycol, ethylene glycol dimethyl ether, dimethyl cellosolve, and DME, is a colorless, aprotic, and liquid ether that is used as a solvent, especially in batteries. Dimethoxyethane is miscible with water.
The azide-alkyne Huisgen cycloaddition is a 1,3-dipolar cycloaddition between an azide and a terminal or internal alkyne to give a 1,2,3-triazole. Rolf Huisgen was the first to understand the scope of this organic reaction. American chemist Karl Barry Sharpless has referred to copper-catalyzed version of this cycloaddition as "the cream of the crop" of click chemistry and "the premier example of a click reaction".
Fluorosulfuric acid is the inorganic compound with the chemical formula HSO3F. It is one of the strongest acids commercially available. It is a tetrahedral molecule and is closely related to sulfuric acid, H2SO4, substituting a fluorine atom for one of the hydroxyl groups. It is a colourless liquid, although commercial samples are often yellow.
An inorganic nonaqueous solvent is a solvent other than water, that is not an organic compound. These solvents are used in chemical research and industry for reactions that cannot occur in aqueous solutions or require a special environment. Inorganic nonaqueous solvents can be classified into two groups, protic solvents and aprotic solvents. Early studies on inorganic nonaqueous solvents evaluated ammonia, hydrogen fluoride, sulfuric acid, as well as more specialized solvents, hydrazine, and selenium oxychloride.
Potassium tert-butoxide (or potassium t-butoxide) is a chemical compound with the formula [(CH3)3COK]n (abbr. KOtBu). This colourless solid is a strong base (pKa of conjugate acid around 17), which is useful in organic synthesis. The compound is often depicted as a salt, and it often behaves as such, but its ionization depends on the solvent.
p-Toluenesulfonic acid (PTSA, pTSA, or pTsOH) or tosylic acid (TsOH) is an organic compound with the formula CH3C6H4SO3H. It is a white extremely hygroscopic solid that is soluble in water, alcohols, and other polar organic solvents. The CH3C6H4SO2 group is known as the tosyl group and is often abbreviated as Ts or Tos. Most often, TsOH refers to the monohydrate, TsOH.H2O.
Propylene carbonate (often abbreviated PC) is an organic compound with the formula C4H6O3. It is a cyclic carbonate ester derived from propylene glycol. This colorless and odorless liquid is useful as a polar, aprotic solvent. Propylene carbonate is chiral, but is used as the racemic mixture in most contexts.
Leveling effect or solvent leveling refers to the effect of solvent on the properties of acids and bases. The strength of a strong acid is limited ("leveled") by the basicity of the solvent. Similarly the strength of a strong base is leveled by the acidity of the solvent. When a strong acid is dissolved in water, it reacts with it to form hydronium ion (H3O+). An example of this would be the following reaction, where "HA" is the strong acid:
1,3-Dimethyl-2-imidazolidinone (DMI) is a cyclic urea used as a high-boiling polar aprotic solvent. This colourless, highly polar solvent has high thermal and chemical stability. Together with homologous solvent DMPU, since the 1970s it serves as an analog of tetramethylurea. It can be prepared from 1,2-dimethylethylenediamine by reaction with phosgene.
Extraction in chemistry is a separation process consisting of the separation of a substance from a matrix. The distribution of a solute between two phases is an equilibrium condition described by partition theory. This is based on exactly how the analyte moves from the initial solvent into the extracting solvent. The term washing may also be used to refer to an extraction in which impurities are extracted from the solvent containing the desired compound.
Tetramethylurea 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. Tetramethylurea is a colorless liquid with mild aromatic odor. Unusual for an urea is the liquid state of tetramethylurea in a range of > 170 °C.
In chemistry, a protic solvent is a solvent that has a hydrogen atom bound to an oxygen, a nitrogen, or fluoride. In general terms, any solvent that contains a labile H+ is called a protic solvent. The molecules of such solvents readily donate protons to solutes, often via hydrogen bonding. Water is the most common protic solvent. Conversely, polar aprotic solvents cannot donate protons but still have the ability to dissolve many salts.