Question

1)Dimethyl sulfoxide (DMSO) is not significantly toxic, but it is nevertheless one of the most hazardous solvents commonly encountered in chemistry laboratories. Explain the particular danger posed by DMSO.

2)Explain why a solvent trap on a vacuum line must not be left under static vacuum while immersed in liquid nitrogen.

3)The monomethylmercury(II) cation, MeHg⁺, is a notorious soft-acid poison, whose ingestion causes a range of severe neurological symptoms. Since MeHg⁺ accumulates in many species of fish, some health authorities recommend that humans minimize their consumption of those fish. However, some MeHg⁺-rich fish seem not to give rise to neurological problems in humans, even when eaten frequently. Many of these fish contain high levels of organoselenium compounds. It has thus been suggested that the mercury/selenium molar ratio in a fish’s tissue is a better indicator of potential toxicity than the mercury content alone. Propose a chemical rationale for this guideline.

Answer 1

1.

DMSO is an excellent solvent in the sense that it can dissolve many organic and inorganic compounds. DMSO has the ability to penetrate skin. It will get absorbed through the skin along with substances dissolved in it. Although DMSO itself is not significantly toxic, the toxic and hazardous compounds dissolved in DMSO in the laboratory can get absorbed through the skin if the dissolved toxic and hazardous compounds comes in contact with the skin.