Odor unpleasant

Chemical Designation - Synonyms Dimethylacetic acid Isopropylformic acid 2-Methylpropanoic acid alpha-Methylpropionic acid Propane-2-carboxylic acid Chemical Formula (CH3)2CHCOOH. Observable Characteristics(asshipped) Liquid Color Colorless Odor Unpleasant, acrid. 

Observable Characteristics - Physical State (as shipped) Liquid Color Dark Odor Unpleasant, acrid. 

A knowledge of these compounds is important because they often have undesirable attributes, e.g., unpleasant odor, the SO2 formed by combustion, catalyst poisoning. There are a number of refining processes to eliminate sulfur compounds. 

There is no reliable standard method to characterize odor and specifications often indicate merely a not-unpleasant odor . 

A collection of physical prop erties of some representative amines is given in Appendix 1 Most commonly encoun tered alkylamines are liquids with unpleasant fishy odors... 

Whatever the physiology of odor perception may be, the sense of smell is keener than that of taste (22). If flavors are classed into odors and tastes as is common practice in science, it can be calculated that there are probably more than 10 possible sensations of odor and only a few, perhaps five, sensations of taste (13,21,35—37). Just as a hereditary or genetic factor may cause taste variations between individuals toward phenylthiourea, a similar factor may be in operation with odor. The odor of the steroid androsterone, found in many foods and human sweat, may eflcit different responses from different individuals. Some are very sensitive to it and find it unpleasant. To others, who are less sensitive to it, it has a musk or sandalwood-like smell. Approximately 50% of the adults tested cannot detect any odor even at extremely high concentrations. It is befleved that this abiUty is genetically determined (38). 

Cacosmia. Perception of persistent or intermittent unpleasant odor. 

The presence of ammonia and hydrogen peroxide in permanent hair color products is a disadvantage. Both are considered by consumers to be harsh chemicals. The odor of ammonia is unpleasant for a personal care product. Monoethanol amine has been used as a substitute for ammonia in some commercial permanent hair color products. It is not as effective as ammonia in allowing the hair to be lightened but it does not have as strong an odor. 

Mesityl Oxide. Mesityl oxide (MSO) (4-metliyl-3-penten-2-one) is an oily colorless liquid with an unpleasant odor. It exhibits the versatiUty and unusual reactivity associated with conjugated a,P unsaturated carbonyl compounds (172). On standing ia air, mesityl oxide slowly forms bis(3,5,5-trimethyl-l,2-dioxolanyl)-3-peroxide (173). 

Specific scales may be used to rate the perception of intensity of (/) the malodor, and (2) the malodor along with an odorous material designed to modify the malodor. Rating scales may consist of numerical assignments to words, eg, from 0 = no odor to 10 = very strong odor. These same type of scales maybe used to describe both the hedonic acceptabiUty of the net result, ie, from 0 = very unpleasant to 10 = extremely pleasant, and the degree of modification, ie, from 0 = does not modify to 10 = complete elimination or cover-up. 

Denture Adhesives. Fast hydration and gel-forming properties are ideally mated to produce a thick, cushioning fluid between the dentures and gums (100). The biologically inert nature of poly(ethylene oxide) helps reduce unpleasant odors and taste in this type of personal-care product (see... 

Inhalation of aerosols or heated vapors may result in irritation of the nose, throat, and upper respiratory system. Lower molecular weight and branched-chain amines are more volatile and can cause irritation if inhaled. Volatile amines are easily recognized by their unpleasant, fishy odor. 

The unusual physical complaints and findings in workers overexposed to teUurium include somnolence, anorexia, nausea, perspiration, a metallic taste in the mouth and garlic-like odor on the breath (48). The unpleasant odor, attributed to the formation of dimethyl teUuride, has not been associated with any adverse health symptoms. Tellurium compounds and metaboUc products have been identified in exhaled breath, sweat, urine, and feces. Elimination is relatively slow and continuous exposure may result in some accumulation. No definite pathological effects have been observed beyond the physical complaints outlined. Unlike selenium, teUurium has not been proved to be an essential biological trace element. 

Flavor-Masking Deodorant. In addition to its use as a constituent of perfume compositions, vanillin is also useful as a deodorant to mask the unpleasant odor of many manufactured goods. As a masking agent for numerous types of ill-smelling mass-produced industrial products, particularly those of synthetic mbber, plastics, fiber glass, inks, etc, vanillin finds extensive use. It is often the most inexpensive material for the amount of masking effect it provides. Only traces are required for this purpose as the odor of vanillin is perceptible in dilutions of 2 x 10 mg/m of air. Cmde vanillin is acceptable for such purposes. 

The ancient process of stoving is stiU occasionally used to bleach wool and silk with sulfur dioxide. In this process, wet fabrics are hung in chambers of burning sulfur or sulfur dioxide gas for at least 8 h. The fabrics are then washed with sodium sulfite to remove excess sulfur dioxide. Fabric so treated may have unpleasant odors, and the original color eventually returns, but the process is simple and inexpensive. 

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