Replacing DMF (N,N-dimethylformamide, CAS [68-12-2])
DMF is a hazardous solvent and human exposure should be carefully limited. It is classified by the International Agency for Research on Cancer (IARC) as a possible carcinogen and many reports of liver disease have been associated with DMF exposure. DMF is also suspected as a reproductive toxin which can damage the developing fetus.
DMSO has solvent properties which resemble those of DMF. Both are from the same solvent class (dipolar aprotic solvents) and have similar physical properties. Both DMSO and DMF are high boiling solvents with boiling points of 189 and 153°C, respectively. Both are water miscible and highly polar substances and they are used in many similar applications.
The most significant difference between DMSO and DMF is toxicity, which recommends DMSO as a safer replacement for DMF. DMSO is not hepatotoxic and does not cause reproductive problems.
ARTIFICIAL LEATHER PRODUCTION
DMF has been used for many years in Asia to manufacture artificial leather (‘Pleather’). DMF is used to dissolve a polyurethane formulation which is precipitated onto a fabric backing.
Synthesis applications for DMF are very broad but encompass many reactions that run well in DMSO also. In general SN2, SNAr and certain elimination reactions work well in both solvents and it is worthwhile screening DMSO in any reaction using DMF. DMF is hydrolyzed under some conditions to produce dimethylamine.
Membranes for many applications (Reverse osmosis, ultrafiltation, nanofiltration) are manufactured by precipitation of a polymer from a polar solvent like DMF or DMSO. Engineering resins like PEEK, polysulfone and polyethersulfone require polar solvents during solvent casting and DMSO should be considered a viable option.
CARBON FIBER PRODUCTION
The manufacturing of carbon fiber requires a spinning solvent for polyacrylonitrile (PAN) precursor. The PAN precursor is dissolved and the resulting ‘dope’ solution is forced through a spinnerette and into a water bath. At this point the solvent dissolves into the bath and the polymer precipitates as a monofilament fiber. DMAc, DMF and DMSO are all used to manufacture on an industrial scale and there are engineering companies that can help you modify your spinning line to use DMSO in carbon fiber production.
ADVICE FOR DMF REFORMULATION
Test pure DMSO in a side-by-side fashion and if DMSO performance is not optimal screen some simple DMSO-cosolvent mixtures. Start with cosolvent mixtures of 1:3, 1:1, 3:1 cosolvent / DMSO. Alkanolamines like monoethanolamine and triethanolamine at relatively low levels (5 wt%) can help DMSO act more closely like DMF.