fumarates and dimethyl-maleate

Chairs and sofas imported from China to Europe were shown to contain dimethyl fumarate (DMF), a sensitizing, volatile chemical. Many of the sensitized patients also had positive patch test reactions to acrylates.. To analyse the occurrence and strength of DMF sensitization and the appearance of concomitant reactions.. Patch testing with DMF in concentrations of 0.1-0.00001% was carried out in 37 patients. Diethyl fumarate (DEF), diethyl maleate (DEM), dimethyl maleate (DMM), ethyl acrylate (EA), methyl acrylate (MA), and methyl methacrylate (MMA) were also tested with a dilution series at equimolar concentrations.. The lowest concentration of DMF eliciting a reaction varied between 0.0001% and 0.1% and all but four patients reacted concurrently to DEF. DEM elicited positive patch test reactions in 21/37 patients and DMM reactions were seen in all 9 patients tested. EA elicited positive reactions in 13/37 patients and a positive MA reaction was seen in 7/37 patients, 2 of whom also reacted to MMA.. The strength of the sensitization to DMF showed variation and concurrent reactions were common. Concurrent reactions to (meth)acrylates were seen in patients, who reacted to lower (0.001% or less) DMF concentration probably elicited by cross-reactivity.

Topics: Acrylates; Adult; China; Dermatitis, Allergic Contact; Dimethyl Fumarate; Female; Finland; Fumarates; Humans; Interior Design and Furnishings; Male; Maleates; Methylmethacrylate; Middle Aged; Patch Tests; United Kingdom

Structural analysis of the bromo-beta-lactones obtained by addition of bromine to aqueous solutions of disodium 2,3-dimethylmaleate and 2,3-dimethylfumarate reveals stereochemistries opposite to those originally assigned in 1937: cis alkene yields erythro lactone, and trans alkene yields threo lactone. B3LYP/6-31+G(d) calculations using a PCM description of aqueous solvation confirm the validity of our proposed mechanism, in which the first-formed intermediate in each case is an alpha-lactone. The cyclic bromonium species is not an intermediate. An alternative pathway leading directly from cis alkene to cis lactone, via an unusual frontside displacement mechanism, is over 20 kJ mol(-1) higher in free energy. Hydrolysis of the bromo-beta-lactones yields bromohydrins whose stereochemistries as determined by X-ray crystallography indicate stereospecific formation by acyl-oxygen cleavage of the lactone ring, again contrary to the original view.

Topics: Bromine; Computers, Molecular; Crystallography, X-Ray; Dimethyl Fumarate; Fumarates; Hydrolysis; Lactones; Maleates; Models, Chemical; Molecular Structure; Sodium; Stereoisomerism