Chemical properties of pharmaceutical grade dimethyl sulfoxide

Pharmaceutical grade dimethyl sulfoxide CAS67-68-5 Use Dimethyl sulfoxide and acid chloride substances such as, benzoyl chloride, acetyl chloride, benziodoyl chloride, thionyl chloride, sulfonyl chloride, and so on, when in contact, a fierce exothermic decomposition reaction
occurs.

Combined with nitric acid, it forms (CH3)2SO· HNO3
。
The interaction with barium carbonate can regenerate
dimethyl sulfoxide.

With concentrated action, it forms a dimethyl sulfur compound
.

Colorless viscous liquid
.

Flammable, almost odorless, with a bitter taste, hygroscopic
.

In addition to petroleum ethers, it can dissolve general organic solvents
.

It can be miscible with water, ethanol, acetone, acetaldehyde, pyridine, ethyl acetate, dibutyl phthalate, dioxane and aromatic compounds, etc.
, and is insoluble in aliphatic hydrocarbon compounds
other than acetylene.

It has strong hygroscopicity, at 20 ° C, when the relative humidity is 60%, it can absorb moisture equivalent to 70% of its own weight from the
air.

The product is a weak oxidant, water-free dimethyl sulfoxide is non-corrosive to metals
.

When containing water against iron; Metals such as copper are corrosive, but not corrosive
to aluminum.

Stable
to alkalis.

Heating in the presence of acids produces small amounts of methyl mercaptan, formaldehyde, and dimethylsulfide; Compounds
such as methanesulfonic acid.

There is a decomposition phenomenon at high temperature, a violent reaction can occur in case of chlorine, burning in the air to emit a light blue flame [check] acidity Take this product 50.
0g, add 100ml of water to dissolve, add phenolphthalein indicator solution 0.
1ml, titrate with sodium hydroxide titration solution (0.
01mol/ L) until the solution appears pink, consume the volume of sodium hydroxide titration solution (0.
01mol / L) shall not exceed 5.
0ml
.

Absorbance Take an appropriate amount of this product, put in dry nitrogen for 15 minutes, take water as a blank, illuminate the ultraviolet- visible spectrophotometry (general rule 0401), and measure it immediately.
The absorbance at the wavelength of 275 nm shall not be greater than 0.
30; the absorbance at the wavelength of 285 nm and 295 nm shall not be greater than 0.
20; the ratio of absorbance at the wavelength of 285 nm and 295 nm to the absorbance at the wavelength of 275 nm shall not exceed 0.
65 and 0.
45, respectively; in the wavelength range of 270 to 350 nm, there shall be no maximum absorption peak
.

Potassium hydroxide deeper precision measure of this product 25ml, placed in a 50ml measuring bottle, add water 0.
5ml and potassium hydroxide 1.
0g, plug, heat on the water bath for 20 minutes, let cool, put the solution in a 1cm absorption tank, take water as a blank solution, according to the ultraviolet - visible spectrophotometry (general 0401), at a wavelength of 350 nm to determine the absorbance, not more than 0.
023
.

Moisture Take this product, according to the moisture determination method (General Principle 0832 First Method 1), the moisture content shall not exceed 0.
2%.
Relevant substances Take 5.
0g of this product, precision weighing, placed in a 10ml measuring bottle, precision add internal standard solution (take an appropriate amount of diphenylmethane, dilute with acetone to make a solution containing 1.
25mg per 1ml) 1ml, dilute with acetone to the scale, shake well, as a test solution; take another product 50.
0mg, precision weighing, placed in a 100ml measuring bottle, precision plus internal standard solution 10ml, diluted with acetone to the scale, shake well, as a control solution; take dimethyl sulfoxide control product 50.
0mg[1], precision weighing, Place in a 100ml measuring flask, add 10ml of the internal standard solution, dilute with acetone to the scale, shake well, as a control solution; According to the gas chromatography (general 0521) test, the capillary column with polyethylene glycol 20M (or similar polarity) as the fixative solution is the column, the column temperature is 150 °C, the inlet temperature is 230 °C, the detector temperature is 250 °C, and the shunt ratio is 20:1
.

Precisely take 2 μl of the control solution and inject it into the gas chromatograph, record the chromatogram, and the theoretical plate number is calculated according to the dimethyl sulfone peak, which should not be less than 5000
.

A precise amount of 2 μl of the test solution and 2 μl of the control solution were injected into the gas chromatograph, and the chromatogram was recorded to 3 times
the retention time of the principal component peak.

If the test solution is shown to dimethyl sulfone peak, the ratio of the peak area of diphenylmethane shall not be greater than the ratio of dimethyl sulfone to the peak area of diphenylmethane in the control solution (0.
1%), and the ratio of the peak area of all impurities (except the main peak and the internal standard peak) to the peak area of diphenylmethane shall not be greater than the ratio of dimethyl sulfoxide to the peak area of diphenylmethane in the control solution (0.
1%)
.

Non-volatile residue Take 100g of this product, weigh it precisely, place it at 105 °C to dry to a constant weight evaporation dish, slowly evaporate to dry on the built-in electric heating plate in the fume hood (no boiling), and dry at 105 °C for 3 hours
.

Residues must not exceed 0.
01%.