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Ricerche Resine CasteZcanza (Varese) , ItalyWe have ascertained that aqueous solutions of formaldehyde absorb hydrogen sulfide proportionally to the formaldehyde present in solution. The highest molar ratio obtainable in solution is equivalent to the value CHzO/HzS = 2. When this ratio is reached, regardless of the initial concentration of formaldehyde, if the solutions are maintained constantly under pressure of hydrogen sulfide, separation of a solid product begins. Varioua chemical and physical studies indicate that the first solid separated from this system ia HSCH~SCHZSCHIOCH~OH. A possible mechanism of formation of this compound from the liquid phase is discussed.Many investigators have studied the interaction of hydrogen sulfide with aqueous solutions of formaldehyde in the presence of strong acids, which leads to formation of the cyclic trimer of thioformaldehyde (1,3,5,-trithmne) .Hofman' first reported this reaction, while Bonst and Constable2 described conditions leading to high yields (92-94%) of the trithiane.Baumana proposed that the intermediate I plays an important role in the reaction :In the presence of strong acids, I may react giving trithiane (11) with elimination of three molecules of water. Bogdanski and Chrzaszcrewki* ascertained that the reaction proceeds essentially as proposed by Bauman and while reaction (1) is fast, reaction (2) is slow. Therefore the intermediate obtained by reaction (1) may react to form such other intermediates as CHZ(SH)Z (111) and (H0CH2)8 (IV).We have ascertained that the reaction of hydrogen sulfide with aqueous formaldehyde, under suitable conditions616 in the presence of sulfuric acid, gives rise to a polymer with a polythiomethylene structure.On the other hand, few investigations have been carried out on the reaction of hydrogen sulfide with aqueous solutions of formaldehyde at normal pH (2.5-3.5). These investigations are summarized in the patent of Marks,' according to which a white solid having a sulfur content of about 51.5% and a melting point of 8OOC. separates out on saturating commercial solutions of formaldehyde with hydrogen sulfide. No further data regarding the solid so precipitated and the progressive uptake of hydrogen sulfide by aqueous solutions of formaldehyde'were available to date.Therefore, it was in our purpose to study the reaction between hydrogen sulfide and aqueous solutions of formaldehyde. The conditions that give rise to the formation of a solid product were investigated and the properties of this compound determined.. RESULTSIn order to study this reaction we allowed aqueous solutions of formalde hyde (at their standard pH) to absorb hydrogen sulfide and determined the content of formaldehyde and hydrogen sulfide in the liquid phase. All our

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STJMMARY:High molecular weight polyamides were prepared from fumaric acid dichloride and unsubstituted aliphatic diamines, by the interfacial polycondensation method.The influence exerted by the molar ratio of the reagents, by their concentration, by the acceptor of the acid and by the nature of the organic solvent on both yield and inherent viscosity of the polyfumaramide obtained from trimethylenediamine was studied.The polymers obtained are partially crystalline and infusible; on heating under vacuum they degrade a t about 290 "C. They are soluble exclusively in strong acids, such as sulphuric and trifluoroacetic acids. ZUSAMMENFASSUNG:Hochmolekulare Polyamide wurden durch Grenzflachen-Polykondensation aus Fumarsauredichlorid und unsubstituierten aliphatischen Diaminen hergestellt.Der EintluD des Molverhiltnisses der Reaktionspartner, ihrer Konzentration, des Saure-Akzeptors und der Natur des organischen Losungsmittels auf die Ausbeute und die Viskositat der aus Trimethylendiamin erhaltenen Polyfumaramide w r d e untersucht.Die erhaltenen Polymeren sind teilweise kristallin und unschmelzbar. Durch Erhitzen im Vakuum werden sie bei etwa 29OoC abgebaut. Sie sind nur in starken Sauren wie Schwefelsaure oder Trifluoressigsaure loslich.