Sulfur interactions with metal

The chemistry of chlorine, as well as other halogens, plays an important role in combustion and in a number of industrial processes. The reactions of chorine and chlorinated hydrocarbons are important in incineration of hazardous chemical wastes, which frequently contain these compounds. Also fuels such as biomass may contain significant amounts of chlorine. In biomass combustion, chlorine interacts with sulfur and alkali metals, a chemistry that has considerable implications for aerosol formation, deposit formation, and corrosion but is rather poorly understood. 

Modifying the Active Conformation of Biomolecules. Class B metals such as Hg have been shown to alter the steric conformation of proteins via interactions with sulfur atoms, particularly disulphide bonds. For example, Hg insertion between the two sulfurs involved in a disulfide bond can significantly alter the shape of the protein and reduce or abolish its activity. This has been demonstrated with ribonuclease, for example. 

Chakrabarti, P. Geometry of interaction of metal ions with sulfur-containing ligands in proteins. Biochemistry 28, 6081-6085 (1989). 

Arsenic is extremely toxic (Box 15.1). Like lead(II) and mercury(II), arsenic(III) is a soft metal centre and interacts with sulfur-containing residues in proteins. 

The cellulose fiber in paper is attacked and weakened by sulfur dioxide. Paper made before about 1750 is not significantly affected by sulfur dioxide (11). At about that time, the manufacture of paper changed to a chemical treatment process that broke down the wood fiber more rapidly. It is thought that this process introduces trace quantities of metals, which catalyze the conversion of sulfur dioxide to sulfuric add. Sulfuric acid causes the paper to become brittle and more subject to cracking and tearing. New papers have become available to minimize the interaction with SO2. 

Furthermore, the strongly metallic character of selenium weakens the C-Se bond and thus favors reactions involving opening of the ring. The basicity of the three heterocycles is approximately in the same order, the nitrogen atom of selenazole and thiazole possessing much the same properties as the heteroatom of pyridine. Of the two carbon atoms ortho to nitrogen, that is, the 2-carbon and the 4-carbon, only the one in the 2-position is fairly active as a result of its interaction with selenium or sulfur. The 4- and 5-positions of thiazole and selenazole are more susceptible to electrophilic substitution than the 3- and 5-positions of pyridine. This is particularly true of the 5-position of selenazole. Thus it can be said that the 2- and 5-positions of the selenazoles and thiazoles... 

Rodriguez JA, Hrbek J (1999) Interaction of sulfur with well-defined metal and oxide surfaces Unravehng the mysteries behind catalyst poisoning and desulfurization. Acc Chem Res 32 719-728... 

Passage of thionyl chloride through a flexible metal transfer hose which was contaminated with water or sodium hydroxide solution caused the hose to burst. Interaction with water violently decomposes the chloride to hydrogen chloride (2 mol) and sulfur dioxide (1 mol), the total expansion ratio from liquid to gas being 993 1 at 20° C, so very high pressures may be generated. 

From the results with the isolable ylides 350, it can be concluded that the fate of less stable, non-isolated sulfonium ylides depends dramatically on their respective substituents 336,338). Thus, the outcome of these reactions is programmed at the ylide stage and not during interaction of a presumed metal carbene with the sulfur-containing substrate. 

Longer Hg-7r interactions are observed in the /> ra-/-butylcalix[4]arene mercury complex 162. The mercury atom forms primary bonds with the two sulfur atoms and engages in weaker secondary interactions with two arene rings of the calixarene whose centroids sit at 3.07-3.11 A from the metal center.201... 

Cation-selective ionophores are the most successful in polymeric ISEs and selectivi-ties exceeding ten orders of magnitude became quite common. The cation-ionophore binding occurs dominantly due to Lewis interactions and could be understood in terms of hard and soft acid and bases theory (HSAB). While hard base oxygen atoms originate from ester, ether or carbonyl functionalities, and interact with hard acid alkaline cations, the softer sulfur or nitrogen atoms better bind with transition metal ions. Cation... 

---