Except where noted otherwise, data are
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references
Dimethyl sulfoxide (DMSO) is the chemical
compound with the formula (CH3)2SO.
This colourless liquid is an
important polar aprotic solvent that dissolves both
polar and non-polar compounds and is miscible in a wide
range of organic solvents as well as water. It has a
distinctive property of penetrating the skin very
readily, allowing the handler to taste it. Its taste has
been described as oyster- or garlic-like.
Dimethyl sulfoxide is a by-product
of wood pulping. A supplier of DMSO is the Gaylord
Chemical Corporation in the USA.
DMSO is an important polar aprotic
solvent. It is less toxic than other members of this
class such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone,
HMPA. Because of its excellent solvating power, DMSO is
frequently used as solvent for chemical reactions
involving salts, most notably Finkelstein reactions and
other nucleophilic substitutions. Because DMSO is only
weakly acidic, it tolerates relatively strong bases, and
as such has been extensively used in the study and
chemistry of carbanions. The work of the Bordwell group
has provided a valuable set of non-aqueous pKa values
(C-H, O-H, S-H and N-H acidities) for hundreds of
organic compounds in DMSO.
A practical problem with DMSO as a
solvent is its high boiling point, thus its solutions
are not typically evaporated. Instead, reactions
conducted in DMSO are often diluted with water to
precipitate or phase separate organic products. DMSO is
an effective paint stripper, being safer than many of
the others such as nitromethane and dichloromethane. The
relatively high freezing point of DMSO means that at, or
just below, room temperature it is a solid, which can
limit its utility in some chemical processes (e.g.
crystallisation with cooling).
In its deuterated form, i.e. DMSO-d6,
it is a useful but expensive solvent for NMR
spectroscopy, again due to its ability to dissolve a
wide range of analytes, its own simple spectrum, and its
suitability for high-temperature NMR spectroscopic
studies. Disadvantages to the use of DMSO-d6
are its high viscosity, which broadens signals, and high
boiling point, which interferes with sample recovery
from the NMR solvent. Often it is used with
deuterochloroform, because the 1:1 mixture has a lower
The sulfur center in DMSO is
nucleophilic toward soft electrophiles and the oxygen is
nucleophilic toward hard electrophiles. The methyl
groups of DMSO are somewhat acidic in character (pKa=35)
due to the stabilization of the resultant carbanion by
the S(O)R group, and for example are deprotonated with
DMSO reacts with methyl iodide to
form a sulfoxonium salt [(CH3)3SO]I,
which can be deprotonated with sodium hydride to form
the sulfur ylide:
+ CH3I → [(CH3)3SO]I
+ NaH → [(CH3)2CH2SO
+ NaI + H2
In organic synthesis, DMSO is used
as an oxidant, such as the Pfitzner-Moffatt oxidation
and the Swern oxidation.
Products of ozonolysis,
trioxolanes, are quenched with dimethyl sulfide to
produce aldehydes and DMSO.
DMSO is used in the PCR reaction to
inhibit secondary structures in the DNA template or the
DNA primers. It is added to the PCR mix before reacting,
where it interferes with the self-complementarity of the
DNA, allowing otherwise troublesome reactions to occur.
However, use of DMSO in PCR increases the mutation rate.
DMSO also sees use as a
cryoprotectant, added to cell media in order to prevent
the cells dying as they are frozen. Approximately 10%
may be used with a slow-freeze method, and the cells may
be frozen at -20°C or stored in liquid nitrogen safely.
In cryobiology DMSO has been used
as a cryoprotectant and is still an important
constituent of cryoprotectant vitrification mixtures
used to preserve organs, tissues, and cell suspensions.
Without it, up to 90 percent of frozen cells will become
inactive. It is particularly important in the freezing
and long-term storage of embryonic stem cells and
hematopoietic stem cells, which are often frozen in a
mixture of 10% DMSO and 90% fetal calf serum. As part of
an autologous bone marrow transplant the DMSO is
re-infused along with the patient's own hematopoietic
Use of DMSO in medicine dates from
around 1963, when a University of Oregon Medical School
team, headed by Stanley Jacob, discovered it could
penetrate the skin and other membranes without damaging
them and could carry other compounds into a biological
In a 1978 study at the Cleveland
Clinic Foundation in Cleveland, Ohio, researchers
concluded that DMSO brought significant relief to the
majority of the 213 patients with inflammatory
genitourinary disorders that were studied. They
recommended DMSO for all inflammatory conditions not
caused by infection or tumour in which symptoms were
severe or patients failed to respond to conventional
Some people report an onion- or
garlic-like taste after touching DMSO. (Onion and garlic
also derive their stinginess from sulfoxides
syn-propanethial-S-oxide and allicin.) In the medical
field DMSO is predominantly used as a topical analgesic,
a vehicle for topical application of pharmaceuticals, as
an anti-inflammatory and an antioxidant.
It has been examined for the treatment of numerous
conditions and ailments. Also, DMSO is commonly used in
the veterinary field as a liniment for horses.
Because DMSO increases the rate of
absorption of some compounds through organic tissues
including skin, it can be used as a drug delivery
Dimethyl sulfoxide dissolves a
variety of organic substances, including carbohydrates,
polymers, peptides, as well as many inorganic salts and
gases. Loading levels of 50-60 wt.% are often observed
vs 10-20 wt.% with typical solvents. For this reason
DMSO plays a role in sample management and
High-throughput screening operations in drug design.
Wearing safety glasses is
recommended because DMSO can cause chronic damage to the
eyes. Glove selection is important when working with
DMSO. Thick rubber gloves are recommended. Nitrile
gloves, which are very commonly used in chemical
laboratories, have been found to dissolve rapidly with
exposure to DMSO. Because DMSO easily penetrates the
skin, substances dissolved in DMSO may be quickly
absorbed. For instance, a solution of sodium cyanide in
DMSO can cause cyanide poisoning through skin contact.
DMSO by itself has low toxicity. Dimethyl sulfoxide can
produce an explosive reaction when exposed to acid
chlorides; at a low temperature, this reaction produces
the oxidant for Swern oxidation.
Recently, it was found that DMSO
waste disposal into sewers can cause environmental odor
problems in cities: Waste water bacteria transform DMSO
under hypoxic (anoxic) conditions into dimethyl sulfide
(DMS) that is slightly toxic and has a strong
disagreeable odor, similar to rotten cabbage.
(1990). "Oxidation of Alcohols by Activated Dimethyl
Sulfoxide and Related Reactions: An Update".
Dimethyl Sulfoxide in Treatment of Inflammatory
Drugs.com (2007-03-27). Nuvo announces further
update on discussions with the FDA related to review
of Pennsaid. Retrieved on 2008-05-01.
Balakin, K. V.,
Savchuk, N. P., Tetko I. V. (2006). "In silico
approaches to prediction of aqueous and DMSO
solubility of drug-like compounds: trends, problems
Current Medicinal Chemistry13 (2):
Carley W. DMSO May Have Caused Death of Woman,
Makers of 'Wonder' Drug Warn Doctors. Wall Street
Journal. September 9, 1965:6.
Safety data for methyl sulfoxide. Oxford University.
Chemical Hygiene Plan. Cornell University (September
Vignes, Robert (August 2000). Dimethyl Sulfoxide
(DMSO): A "new" clean, unique, superior solvent,
American Chemical Society Annual Meeting
Novak, J., Witherspoon, J. (2006). "Dimethyl
Sulfoxide (DMSO) Waste Residues and Municipal Waste
Water Odor by Dimethyl Sulfide (DMS): the North-East
WPCP Plant of Philadelphia.". Environmental
Science and Technology40 (1): 202-207.
doi:10.1021/es051312a S0013-936X(05)01312-X .