Methyl odor caused

Ozone can sometimes solve taste and odor problems when the taste and odor are caused by unsaturated organic compounds. For example, unsaturated aldehydes, which are important taste and odor by-products of Synura species, are readily oxidizable by ozone. Also, ozone is quite effective in removing 2-methyl-isoborneol (MIB), which causes the musty-earthy taste and odor and is rarely removed by conventional water treatment methods, from the natural water. However, if the taste- and odor-causing compounds are saturated, ozone treatment may have little effect. ... 

Many commercial grades of pine oil are available and are specified by physical properties and total alcohol content. Some commercial pine oils and the typical physical properties are Hsted in Table 4. Other grades of pine oil may constitute a blend of synthetic and natural pine oil and give the product a different odor characteristic. The odor difference is caused by the presence of phenoHc ethers anethole and methyl chavicol. 

The most striking characteristic of thiols is their appalling odor. Skunk scent, for instance, is caused primarily by the simple thiols 3-methyl-1-butanethiol and 2-butene-l-thiol. Volatile thiols such as ethanethiol are also added to natural gas and liquefied propane to serve as an easily detectable warning in case of leaks. 

Other preparations and isolations. If damp methylenedi(nitroformamide) is allowed to stand for several days, the odor of formic acid is noticed, and MEDINA can be isolated from the residue (Ref 11, p 14). The details of scale-up to 150 lb batches, including exp details and flow sheets, and further scale-up with the aim of prodn of 1000 lbs are given. The report describes a fume-off and fire which occurred during the S3rd run. The cause was attributed to a stuck valve which allowed nitric acid to build up in the reactor (Ref 13, p 57). In Ref 16, p 73 there are cost analysis data for pilot plant and large scale prodn, flow sheet for a proposed coml plant, and material balances. The action of acet anhydr on N,Nf-bis(hydroxy-methyl)MEDlNA regenerates MEDINA (Ref 6) the diNa salt of N. N trinitrotrimethylene-diamine, on warming with me ale, ppts the Na salt of MEDINA... 

In humans, short-term exposure to 300 ppm was objectionable, causing headache and throat irritation 2 00 ppm caused mild irritation of eyes 100 ppm caused slight nose and throat irritation. No significant neurobehav-ioral effects (as determined by a series of psychomotor tests) were found in volunteers from 4-hour exposures to methyl ethyl ketone at 200 ppm significant odor and irritant effects were reported. ... 

Treated soil must be left unplanted for about 2 wk, because PS damages seeds. It is also a warning agent in fumigants, such as methyl bromide, because of its strong odor. 5,16 t 1 ppm in air, it causes lacrlmatlon and smarting paln.3... 

Blackcurrant absolute (Bourgeons de cassis absolute, cassis absolute) is obtained by solvent extraction via the concrete obtained from the dormant buds of the blackcurrant bush Ribes nigrum L. (Saxifragaceae). The yield is ca. 3%. Blackcurrant absolute is a dark green paste with the characteristic, powerful, penetrating odor of blackcurrants. The typical catty note is caused by a sulfurous trace constituent, 4-methoxy-2-methyl-2-butenethiol [80324-91-0] [286-288]. 

Figure G1.1.3 shows a chromatogram of the headspace of Concord grape essence prepared by direct injection. At retention index 1320 is the peak caused by methyl anthranilate, one of the strongest odorants characterizing Concord grapes however, (i-damascenone, the second most potent odorant in Concord grapes, elutes at 1360 but is not visible. This is because P-damascenone is lOOOx more potent (i.e., its odor threshold is lOOOx lower than methyl anthranilate). This is typical result for the direct injection of headspace from natural products. Figure Gl.1.4, on the other hand, shows the injection of an extract of Concord grape essence concentrated 500-fold with the fi-damascenone peak large enough for quantitation.

Health and Safety Factors. Mesityl oxide is more toxic than saturated ketones and is highly irritating to all tissues on vapor or liquid contact and for this reason sales of mesityl oxide ceased in the United States in 1986. It is absorbed through intact skin, and prolonged exposure can damage liver, kidneys, and lungs. Repeated exposure to vapors can cause anemia and leukopenia (187) however, the odor is so intolerable that long-term exposure is unlikely. Mesityl oxide is still produced, but is consumed captively as an intermediate in the production of MIBK, methyl isobutyl carbinol, and isophorone. 

GC—O experiments of a waxed and oiled parquet floor revealed acetaldehyde, methyl propanal, 3-methyl butanal, pentanal, hexanal, heptanal, a-pinene, 1-octen-3-one, 3-pinene, octanal, l-nonen-3-one, nonanal, Z-2-nonenal and E-2 nonenalas the most important odorants (Mayer, Breuer and Mayer, 2000). In contrast the less intense odor of varnished parquet floor was mostly caused by acetaldehyde, butanal, 3-methyl butanal, pentanal, hexanal, a-pinene, benzaldehyde, l-octen-3-one, P-pinene and acetophenone. 

Acetone is a liquid with a pleasant odor. It can act as a narcotic and dissolves fats from skin, causing dermatitis. Methyl- -butyl ketone, a widely used solvent, is a mild neurotoxin. Methylethyl ketone is suspected of having caused neuropathic disorders in shoe factory workers. 

Sizer at al. (20) observed that the compounds causing the pleasant odor which resembled bread crust occur in the basic volatile fraction of white bread. Identification experiments yielded the five pyrazines listed in Table II. A comparison of the odor threshold of each pyrazine in water to its concentration found in bread indicated that 2-ethyl-3-methylpyrazine and 2-methyl-6-propylpyrazine were present at concentrations above their odor thresholds. The authors described the odors of these two pyrazines as "butterscotch, nutty" and "burnt, butterscotch" notes (Table II). 

Methyl acetate forms a colorless liquid with a pleasant odor. It has a melting point of -98 Celsius, and a boiling point of 57 Celsius. It is soluble in water, and miscible with alcohol and ether. Methyl acetate is irritating to the nose and throat. Over exposure may cause headache, drowsiness, and skin contact may cause irritation. It can be prepared by distilling a mixture of methanol with acetic acid in the presence of a small amount of sulfuric acid. 

The presence of unsymmetrical dialkyl ditcllurium and unsymmetrical diaryl ditellurium" compounds in solution was confirmed by Te-NMR spectroscopy H-NMR spectroscopy , and mass spectroscopy . Cyclohexyl methyl ditellurium was claimed to have been isolated from a reaction mixture obtained by sequential addition of cyclohexyl bromide and methyl iodide to a solution of tetratelluride anions in dimethylformamide . The chromophoric Te —Te group in the aliphatic and aromatic ditellurium compounds imparts a characteristic orange to red color caused by an absorption maximum at approximately 400 nm. Most of the aromatic ditellurium derivatives are stable as solids toward atmospheric agents, but oxidize slowly when dissolved. The short-chain aliphatic ditellurium compounds are distillable red liquids having an obnoxious odor that clings to skin and clothes. Ditellurium compounds with more than ten carbon atoms in each aliphatic group are low melting solids that can be handled in air. 

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