Odorants sulfur-free

In contrast to sulfur-containing tin compounds, tin carboxylates have to be used with antioxidants. The advantage of the use of sulfur-free stabilizers is the good photostability and the lack of odor. These stabilizers, too, need additional lubricants, since they tend to stick to the metal parts of calendars and extruders. ... 

Sulfur-free odorants have been developed and commercialized, but are not yet commonly used [108]. They contain a mixture of 37 wt% methylacrylate, 60 wt.% ethylacrylate and 2.5 wt.% methylethylpyrazine. It has been proven that these components do not affect the performance of a rhodium catalyst during methane steam reforming. 

Tall oil rosin is a by-product of paper manufacturing. Raw wood chips are digested under heat and pressure with a mixture of sodium hydroxide and sodium sulfide. Soluble sodium salts of lignin, rosin, and fatty acids are formed, which are removed from the wood pulp as a dark solution. The soaps of the rosin and fatty acids float to the top of the mixture, where they are skimmed off and treated with sulfuric acid to free the rosin and fatty acids. This mixture, known as cmde tall oil (CTO), is refined further to remove color and odor bodies fractional distillation separates the tall oil rosin acids from the fatty acids (see Tall oil). 

Physical Properties. Sulfur dioxide [7446-09-5] SO2, is a colorless gas with a characteristic pungent, choking odor. Its physical and thermodynamic properties ate Hsted in Table 8. Heat capacity, vapor pressure, heat of vaporization, density, surface tension, viscosity, thermal conductivity, heat of formation, and free energy of formation as functions of temperature ate available (213), as is a detailed discussion of the sulfur dioxide—water system (215). 

Commercial monochloroacetic acid contains many other organic acids, particularly dichloroacetic acid [79 3-6] CI2CHCOOH, which has to be completely converted iato sulfur derivatives to avoid residual chlorine compounds which are harmful for cosmetic apphcations (8). Thioglycohc acid, which has to meet cosmetic specifications, must be free of metal impurities, and must be pure enough to avoid color and odor problems. 

Sulfur compounds are most commonly removed or converted to a harmless form by chemical treatment with lye. Doctor solution, copper chloride, or similar treating agents (Speight, 1999). Hydrorefining processes (Speight, 1999) are also often used in place of chemical treatments. When used as a solvent, naphtha is selected for its low sulfur content and the usual treatment processes remove only sulfur compounds. Naphtha, with its small aromatic content, has a slight odor, but the aromatics increase the solvent power of the naphtha and there is no need to remove aromatics unless odor-free naphtha is specified. 

The ether was dried over calcium chloride and finally over phosphorus pentoxide. The checkers found that after the ether evaporations the odor of thionyl chloride was still present. The last traces of thionyl chloride were best removed at a pressure of 1-2 mm. When free of thionyl chloride the residue no longer has the pungent odor of either hydrogen chloride or sulfur dioxide but has a faint odor typical of sulfonyl chlorides. 

This distillate, which is sufficiently pure for most reactions, solidifies after standing for 4-6 hours. A sample crystallizes from benzene-petroleum ether as off-white prisms, m.p. 61-62°, and is relatively free of sulfureous odor. 

It thus seemed that the origin of the various components in meat volatiles could best be established by analyzing irradiation-induced compounds in meat protein and meat fat separately. Accordingly, a 500-gram sample of meat, the same size of sample normally used in irradiation studies of whole meat, was separated into a protein, a lipid, and a lipoprotein fraction by means of a methanol-chloroform extraction of the fat. The dry, air-free, fractions were then irradiated separately with 6 megarads of gamma radiation in the manner used for whole meat. The analytical results (Table V) show clearly that mainly sulfur compounds and aromatic hydrocarbons are formed in the protein fraction, whereas mainly aliphatic hydrocarbons are formed from the lipid. The lipoprotein fraction produced, as expected, both aliphatic hydrocarbons and sulfur compounds. Only the lipoprotein fraction had a characteristic irradiation odor. 

The need to remove sulfur compounds from petroleum arises not only from the objectionable odor that the thiols impart to petroleum products but also from the instability which sulfur compounds appear to promote in petroleum products. For example, free sulfur, which can be formed in a product by the oxidation of hydrogen sulfide ... 

The free base and hydrochloride salt are white crystalline solids with little or no odor. A slight sulfur-mercaptan odor may be present. 

Carbon disulfide (CS2) is one of the most significant sulfur compounds because of its widespread use and toxicity. This compound has two sulfur atoms, each separately bonded to a carbon atom. This compound is a volatile, colorless liquid (mp, -111°C bp, 46°C). Unlike most organosulfur compounds, it is virtually free of odor. Although its uses are declining, it has numerous applications in chemical synthesis, as a solvent to break down cellulose in viscose rayon manufacture, and in the manufacture of cellophane. It has also been used as an insecticide and fumigant. 

Most manufacturers use soapstock to spray on meal for animal feed, or ship the material to acidulators. Some seed oil producers treat soapstock on site with sulfuric acid at a temperature of 90-95 °C to produce acidulated soapstock (Dijkstra and Segers, 2007). Acidulated soapstock is very dark in color with a strong, rancid, burned odor from the free fatty acids and neutral oils. Free fatty acid content varies and can be in excess of 90%. Moisture content as well as unsaponifiables can be substantial and the pH (based on samples provided to Stepan Company) may vary from 3 to 4.5. An example of a typical analysis of an acid oil sample is listed below (Table 6.2). 

Sulfur Compounds Carefully open the container valve to produce a moderate flow of gas. Do not direct the gas stream toward the face, but deflect a portion of the stream toward the nose. The gas is free from the characteristic odor of sulfur compounds. 

Transfer a 10-mL sample, previously dried with sodium sulfate, into a 125-mL glass-stoppered Erlenmeyer flask previously cooled in an ice bath. Add to the cooled oil 20 mL of dimethyl aniline (monomethyl-free), and mix thoroughly. To the mixture add 8 mL of acetyl chloride and 5 mL of acetic anhydride, cool for several min, permit to stand at room temperature for another 30 min, then immerse the flask in a water bath maintained at 40° 1° for 16 h. Wash the ace-tylated oil with three 75-mL portions of ice water, followed by successive washes with 25-mL portions of 5% sulfuric acid, until the separated acid layer no longer becomes cloudy or emits an odor of dimethyl aniline when made alkaline. After removal of the dimethyl aniline, wash the acetylated oil first with 10 mL of sodium carbonate TS and then with successive portions of water until the washings are neutral to litmus. Finally, dry the acetylated oil with anhydrous sodium sulfate, and proceed as directed for Ester Determination under Esters, this Appendix. Calculate the percentage of linalool (CioHigO) by the equation... 

Odor. Pure sulfur is free of odor odor indicates impurities. While whole wood exudes a very pleasant odor, a large number of useful sulfur modifiers unfortunately exude an unpleasant odor. Often, modified sulfur contains some decomposition products which impart to the final material a faint but insiduous odor to which many people are quite sensitive. Likewise, commercial wood products exude an unpleasant odor from excess formaldehyde which remains unreacted and is released over several months. 

Potassium metabisulfite occurs as white or colorless free-flowing crystals, crystalline powder, or granules, usually with an odor of sulfur dioxide. 

Sulfur dioxide is widely used in water and wastewater treatment plants for dechlori-nating backwash water and wastewaters containing chlorine. It is a colorless gas with a suffocating pungent odor. Sulfite ion, which is formed when SO2 gas dissolves in water, reacts instantaneously with free and combined chlorine according to the following stoichiometry (13) ... 

Calcium thiosulfate is a clear crystalline substance, with a faintly sulfurous odor. It reacts with free as well as combined chlorine. Calcium thiosulfate undergoes the following reactions with chlorine (20) ... 

The nose is an extremely sensitive detector of odors it can be matched only by the most sensitive instrumental techniques. Many smells are identified by comparison with pure compounds diluted by odor-free air until they are near the odor threshold limit. However, with the introduction of flame photometric detectors it has been possible to measure the concentration of the sulfur compounds giving rise to odors in the ppb range with the aid of preconcentration (by a fector of 10 to 10. ... 

Mercaptan sulfur (R-SH) and hydrogen sulfide (H2S) (ASTM D-1219, IP 103, IP 104) are undesirable contaminants because, apart from their corrosive nature, they possess an extremely unpleasant odor. Such compounds should have been removed completely during refining but their presence and that of free sulfur are detected by application of the Doctor test (ASTM D-4952, IP 30). The action on copper of any free or corrosive sulfur present in gasoline may be estimated by a procedure (ASTM D-130, ASTM D-849, IP 154) in which a strip of polished copper is immersed in the sample, which is heated under specified conditions of temperature and time, and any staining of the copper is subsequently compared with the stains on a set of reference copper strips and thus the degree of corrosivity of the test sample determined. 

Refining treatment includes among its objects the removal of such undesirable products as hydrogen sulfide, mercaptan sulfur, and free or corrosive sulfur. Hydrogen sulfide and mercaptans cause objectionable odors, and both are corrosive. The presence of such compounds can be determined by the Doctor test (ASTM D-484, ASTM D-4952, IP 30). The Doctor test (which is pertinent for petroleum product specifications ASTM D-235) ensures that the concentration of these compounds is insufficient to cause such problems in normal use. In the test, the sample is shaken with sodium plumbite solution, a small quantity of sulfur is added, and the mixture is shaken again. The presence of mercaptans, hydrogen sulfide, or both is indicated by discoloration of the sulfur floating at the oil-water interface or by discoloration of either of the phases. 

Yellowish-brown lumps Iresh fracture is liver-brown, slight HgS odor. Dec on exposure to air, forming free sulfur and potassium carbonate and becomes yellow to gray. Freely sol in water, usually with slight residue partially sol in alcohol. Keep tightly closed,... 

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