Skunk, smells

A physical characteristic is their odor 2-butene-1-thiol, CH,CH=CHCH2SH, and 3-methyl-l-butanethiol, CH3CH(CH,)CH2CH2SH, contribute to skunk smell. 

Today,Teenu is used for removing many other things like sap from skin, urushiol from tools, gear and clothing, and even skunk smell from animals. 

Four characteristics of odor are subject to measurement by sensory techniques intensity, detectability, character (quality), and hedonic tone (pleasantness-unpleasantness) (16). Odor intensity is the magnitude of the perceived sensation and is classified by a descriptive scale, e.g., faint-moderate-strong, or a 1-10 numerical scale. The detectability of an odor or threshold limit is not an absolute level but depends on how the odorant is present, e.g., alone or in a mixture. Odor character or qualit) is the characteristic which permits its description or classification by comparison to other odors, i.e., sweet or sour, or like that of a skunk. The last characteristic is the hedonic type, which refers to the acceptability of an odorant. For the infrequent visitor, the smell of a large commercial bread bakery may be of high intensity but pleasant. For the nearby resident, the smell may be less acceptable. 

Mercaptans Compounds containing sulfur which have an extremely offensive skunk-like odor. Also sometimes described as smelling like garlic or onions. Mesh count The number of threads in a linear inch of fabric/wire cloth. 

A thiol contains an —SH group covalently bonded to carbon. Sulfur is just below oxygen in the periodic table, so a thiol is somewhat similar to an alcohol. Still, the chemical and physical properties of thiols differ significantly from those of alcohols. For example, whereas alcohols have inoffensive odors, thiols smell bad. The stench of skunk scent is due to thiols, including 3-methylbutanethiol. Thiols are important in proteins because of their abilities to form S—S linkages, which we describe in Section 13-1. 

Because of their inherent penetrating smell, certain organic sulfur compounds are used for odorization. Repellents from the skunk contain compounds such as trans-2-butene-l-thiol and 3-methyl-1-butanethiol. Ethylmercaptan, because of its extremely low odor threshold, is the favorite compound used as an odorant in natural gas and liquid propane for leak detection. Tetrahydro-thiophene is also often used. Common odorization reagents are summarized in Table 15-1 and Figures 15-1 to 15-3. 

These are volatile compounds and do have rather dreadful smells. They also occur in skunk spray in the form of their acetate esters. These are much less volatile and so contribute less to the immediate odor. However, on contact with water, they are slowly converted to the free thiols, a reaction that accounts for the persistence of skunk odor for days or weeks. The chemical components of skunk defensive secretion vary somewhat from species to species but thiols play a prominent role in all cases. 

The sense of smell in humans is not limited to detection of those volatile molecules inhaled through the nose, termed orthonasal olfaction. Molecules released at the back of the mouth, particularly in the chewing of food, can make their way up through the nasopharynx to the olfactory epithelium, termed retronasal olfaction. This system is activated when air is exhaled. Orthonasal olfaction is used to detect the scent of flowers and perfumes, food aromas, the presence of skunks, and the like. Retronasal olfaction detects the volatile molecules released from food. It is retronasal olfaction that makes a major olfactory contribution to the taste of food. And it is retronasal olfaction that helped to elicit Proust s profound reaction to a madeleine dipped in tea. 

Hydrogen Sulfide—Many sulfur compounds have unpleasant, penetrating smells. Some of these compounds have very complex molecules — just imagine a skunk producing a chemical with this formula CHsCH,CH3Cri,SH The smell of rotten eggs, ou tlic other hand, comes from the simple compound hydrogen sulfide (H-S). 

Sulfur compounds are used to make rubber strong enough to be used in tires, in a process called vulcanization. Sulfur is also used to make detergent, paper, fertilizers, and medicines. Several sulfur compounds have a strong odor to them. Onions, garlic, skunk spray, and even bad breath get their unique odor from sulfur compounds. Sulfur by itself has no smell. 

Veteran smokers can easily tell if a sample of marijuana is bunk, ordinary or special by crushing a bud in one s fingers. When it breaks open, there should be a pungent smell. If its quite good, the fingers should also be somewhat sticky. Some strains have a strong pine, mint or skunk odor. 

Colour is not the only characteristic by which we recognize compounds. All too often it is their odour that lets us know they are around. There are some quite foul organic compounds loo the smell of the skunk is a mixture of two thiols—sulfur compounds containing SH groups. 

The first organosulfur compounds in this book were the dreadful smell of the skunk and the wonderful smell of the truffle, which pigs can detect through a metre of soil and which is so delightful that truffles cost more than their weight in gold. 

As shown in the case of l-octen-3-one in the beginning of this chapter, aroma-active compounds show an interesting indication as media in human-environment interactions the role of this often disliked compound has some similarity to alarm pheromones. Flavor or smell of food can be categorized into food attractant molecules from this point of view. Infants are able to recognize the body odor of their mother and are attracted to it.189 An opposite example is represented by the notorious ability of skunks to spray, in which thiol compounds such as (E)-2-butene-1 -thiol and 3-methyl-l-butanethiol are used as potent repellents190(see Chapter 4.09). 

Human beings can detect and distinguish thousands of different compounds by smell, often with considerable sensitivity and specificity. Most odorants are relatively small organic compounds with sufficient volatility that they can be carried as vapors into the nose. For example, a major component responsible for the smell of almonds is the simple aromatic compound benzaldehyde, whereas the sulfhydryl compound 3-methylbutane-l-thiol is a major component of the smell of skunks. 

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