Sulfur solubility tests

X-ray diffraction of sulfur particles excreted by Thiobacillus sp. showed the presence of orthorhombic sulfur crystals. The solubility of crystalline orthorhombic sulfur in water is known to be only 5 /tg 1 [42]. In the solubility test shown in Fig. 7 it was seen that the biologically produced sulfur particles can be dispersed in water but not in hexadecane, whereas crystalline orthorhombic sulfur is soluble in hexadecane but not in water. The reason for the observed hydrophilicity of the biologically produced sulfur particles has to be attributed to the hydrophilic properties of the surface of the sulfur particles. Because of the relatively high stability of the biologically produced sulfur particles at high salt concentrations, it is concluded that the colloidal stability is not merely based on electrostatic repulsion. It is known that hydrophobic sulfur can be wetted by Thiobacillus thiooxidans bacteria due to formation of organic surface-active substances [43, 44]. 

Test 1 successfully demonstrated the feasibility of the process to use metallic iron to fix sulfur. This test indicates that the activity coefficient of ZnS in matte is very large because the zinc solubility is about 1 wt% even at Pa = 0.34 atm and 1350 C, whereas the normalized zinc solubility in the matte is only 0.24 wt%. 

Purity, as decanol Refractive index at 20 C, Solubility in water at Z0 C Solubility of water in at 20 C Specific gravity at 20/20 Sulfuric acid test (Pt>Co scale) Suspended matter Vapor pressure at 20 C Viscosity at 20 C Water content Weight per gallon at 20 C... 

In some laboratories, comparative analyses begin with solubility tests. The difference between the suspect and the control samples can often be determined quickly through the reaction and the different solubility of the paint binders with a variety of chemical reagents (e.g., chloroform, acetone, concentrated sulfuric acid, etc.) only when differences cannot be detected with these tests is it necessary to employ instrumental methods. 

This set of 5 imknowns will help you make proper observations. They will not be used further in your organic laboratory course. Note that almost all organic compounds, except inert ones, will be soluble in sulfuric acid. This reagent should always be the last one tried, as shown in the Solubility chart. Using solubility tests, distinguish these unknowns by type. Verify your answer with the instructor. Read the discussion sections that follow for details on solubility behavior. A more general discussion of solubility behavior is provided in Technique 10, Section 10.2... 

The above reaction proceeds smoothly under suitable experimental conditions, viz., proper temperature control and acid concentration. The solution of alkyl sulfuric acid may be poured into water, neutralized with excess alkali, and the corresponding alcohol recovered by distillation. When an olefine is treated with concentrated sulfuric acid without special precautions, as in the usual solubility test, only a portion of the compound is converted into a soluble alkyl sulfuric acid, the remaining portion being polymerized to compounds of limited solubility in sulfuric acid. The first step in such a polymerization may be represented thus ... 

Solubility in Cold Concentrated H2SO4.—The sulfuric acid test is of value in differentiating between Groups V and VI. Compounds falling in Groups I, II, III, and IV, as well as indif-... 

A paper was published by Ishiaku and co-workers [11], who investigated the optimum concentration of DeLink to use in the devulcanisation of a sulfur-cured, NR-hased powder that had originated from waste rubber balls and artificial eggs. A solubility test was also developed to assess the degree of crosslink destruction that had taken place. The results obtained showed that the optimum... 

If the chemist wants to know whether her final product is bromo-safrole and not just a bunch of unreacted safrole there is a simple little test she can do. Safrole is soluble (will dissolve in) cold concentrated sulfuric acid. But bromosafrole is insoluble in it. So the chemist can take a shot glass full of straight-from-the-bottle 96% H2SO4 and place it in the freezer until it s ice cold. Then she takes it out and drops a few drops of mystery product into it. If the oil dissolves then the stuff is unreacted safrole. If the oil drops to the bottom and does not dissolve it s the goods. 

Reactions between A -(l-chloroalkyl)pyridinium chlorides 33 and amino acids in organic solvents have a low synthetic value because of the low solubility of the amine partner. A special protocol has been designed and tested in order to circumvent this drawback. Soon after the preparation of the salt, an aqueous solution of the amino acid was introduced in the reaction medium and the two-phase system obtained was heated under reflux for several hours. However, this was not too successful because sulfur dioxide, evolved during the preparation of the salt, was converted into sulfite that acted as an 5-nucleophile. As a result, A -(l-sulfonatoalkyl)pyridinium betaines such as 53 were obtained (Section IV,B,3) (97BSB383). To avoid the formation of such betaines, the salts 33 were isolated and reacted with an aqueous solution of L-cysteine (80) to afford thiazolidine-4-carboxylic acids hydrochlorides 81 (60-80% yields). 

Detailed photochemical studies of RBS and RRS have revealed that the photolysis of RRS produces RBS and NO quantitatively (Scheme 5.6) and the RBS produced undergoes further photodecomposition to generate NO and iron (III) [165, 168]. RBS has been tested as an NO delivery drug to the vascular and brain tissues by thermal as well as photochemical means [169, 170]. Due to the high solubilities in aprotic solvents, Roussin s salts are able to penetrate the endothelial cell membrane easily and deliver NO for hours [169]. RBS has been found to inhibit ADP-induced platelet aggregation [171] and Roussin s salts in general show a bacteriostatic effect, presumably due to the interaction of released NO and iron-sulfur proteins [172]. 

The harmala alkaloids harmaline (368 X = NH) and harmi.ne (369 X = NH) are active reversible inhibitors of monoamine oxidase (MAO). Benzo[ Jthiophene analogs of harmaline (368 X = S) and harmine (369 X = S), when tested in vitro as inhibitors of rat liver MAO, showed that (368 X = S) was 50 times more potent than harmaline, but (369 X = NH or S) were equivalent in potency. The replacement of the indolic nitrogen by sulfur greatly increased the lipid solubility of the molecule, which was reflected in the physiological disposition of the two analogs. 

Alkenes Bromine test Permanganate test Solubility in cone, sulfuric acid Positive for all alkenes Positive for all alkenes All alkenes dissolve... 

Sulfonic acids Sodium fusion test Solubility in aqueous base Presence of sulfur Most sulfonic acids are soluble in dilute sodium hydroxide and generate carbon dioxide with sodium bicarbonate... 

The concentration of lactic acid in the steep has been shown to affect both the yield of starch178 and the quality of the resulting starch.179 Starch yields increased with increasing lactic acid concentration up to —0.5%, and decreased when more than —2% lactic acid was used. Shandera and lackson179 tested starch quality when steeped at 57°C with either 0.2% or 1.5% lactic acid and 0.05% or 0.3% sulfur dioxide. The level of sulfur dioxide had a small effect on starch quality, but the level of lactic acid had a pronounced reduction effect on peak viscosity, shear thinning viscosity, set-back viscosity, pasting viscosity and starch water solubility. 

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