Compounds common examples

The permeability of the skin to a toxic substance is a function of both the substance and the skin. The permeability of the skin varies with both the location and the species that penetrates it. In order to penetrate the skin significantly, a substance must be a liquid or gas or significantly soluble in water or organic solvents. In general, nonpolar, lipid-soluble substances traverse skin more readily than do ionic species. Substances that penetrate skin easily include lipid-soluble endogenous substances (hormones, vitamins D and K) and a number of xenobiotic compounds. Common examples of these are phenol, nicotine, and strychnine. Some military poisons, such as the nerve gas sarin (see Section 18.8), permeate the skin very readily, which greatly adds to then-hazards. In addition to the rate of transport through the skin, an additional factor that influences toxicity via the percutaneous route is the blood flow at the site of exposure. 

In acidic media, polarized multiple bonds often undergo acid catalyzed addition, and a common mode of addition is the Ad 2. Deprotonation of the nucleophile by solvent gives the neutral compound. Common examples of this easily reversible Adg2 reaction are the formation of hydrates (NuH is H2O) and, if NuH is ROH, hemiacetals (from aldehydes) and hemiketals (from ketones). Usually this reaction favors reactants. 

Internal plasticizer ru An agent incorporated in, or co-polymerized with, a resin dming its polymerization to make it softer and more flexible, as opposed to a plasticizer added to the resin during compounding. Common examples occur in oil-modified alkyds, and such materials have considerable practical advantages over externally plasticized systems, where the plasticizer may be lost by evaporation or leached out by water or other agents. 

In teclmology, an economic separation of tlie products of a reaction from tlie solution containing tlie catalyst is necessary. Distillation is a commonly used metliod and, for it to work successfully, tlie products and catalyst must be stable at tlie temperatures of tlie distillation, which are often relatively high some organometallic compounds, for example, may not meet tliis criterion. 

Conjugate acid (Section 1 13) The species formed from a Brpnsted base after it has accepted a proton Conjugate addition (Sections 1010 and 1812) Addition reaction in which the reagent adds to the termini of the con jugated system with migration of the double bond synony mous with 1 4 addition The most common examples include conjugate addition to 1 3 dienes and to a 3 unsaturated car bonyl compounds... 

Detoxifica.tlon. Detoxification systems in the human body often involve reactions that utilize sulfur-containing compounds. For example, reactions in which sulfate esters of potentially toxic compounds are formed, rendering these less toxic or nontoxic, are common as are acetylation reactions involving acetyl—SCoA (45). Another important compound is. Vadenosylmethionine [29908-03-0] (SAM), the active form of methionine. SAM acts as a methylating agent, eg, in detoxification reactions such as the methylation of pyridine derivatives, and in the formation of choline (qv), creatine [60-27-5] carnitine [461-06-3] and epinephrine [329-65-7] (50). 

Common examples of compounds that are amenable to carbon adsorption are aromatics (benzene, toluene) and chlorinated organics (trichloroethylene, trichloroethane [71-55-6, 75 -(9(9-j5y, tetrachloroethylene, polychlorinated biphenyls (PCBs), DDT /T(9-77-77, pentachlorophenol [87-86-5J. Compounds that are not adsorbed effectively by carbon include ethanol [64-17-5], diethylene glycol [111-46-6], and numerous amines (butylamine [109-73-9, 13952-84-6, 75-64-9], triethanolamine [102-71-6], cyclohexylamine [108-91-8], hexamethylenediamine [108-91-8] (1). Wastewater concentrations that are suitable for carbon adsorption are generally less than 5000 mg/L. 

Reduction. Mono- and oligosaccharides can be reduced to polyols (polyhydroxy alcohols) termed alditols (glycitols) (1) (see Sugar alcohols). Common examples of compounds in this class ate D-glucitol (sorbitol) [50-70-4] made by reduction of D-glucose and xyhtol [87-99-0] made from D-xylose. Glycerol [56-87-5] is also an alditol. Reduction of D-fmctose produces a mixture of D-glucitol and D-mannitol [69-65-8],... 

The primary phases all contain impurities. In fact these impurities stabilize the stmctures formed at high temperatures so that decomposition or transformations do not occur during cooling, as occurs with the pure compounds. For example, pure C S exists in at least six polymorphic forms each having a sharply defined temperature range of stability, whereas alite exists in three stabilized forms at room temperature depending on the impurities. Some properties of the more common phases in Portland clinkers are given in Table 2. 

Metal oxides, sulfides, and hydrides form a transition between acid/base and metal catalysts. They catalyze hydrogenation/dehydro-genation as well as many of the reactions catalyzed by acids, such as cracking and isomerization. Their oxidation activity is related to the possibility of two valence states which allow oxygen to be released and reabsorbed alternately. Common examples are oxides of cobalt, iron, zinc, and chromium and hydrides of precious metals that can release hydrogen readily. Sulfide catalysts are more resistant than metals to the formation of coke deposits and to poisoning by sulfur compounds their main application is in hydrodesulfurization. 

Most compounds in which carbon is the key element are classified as organic. Common examples of organic compounds include degreasing solvents, lubricants, and heating and motor fuels. This subsection highlights some of the more common characteristics of organics as they relate to hazards. Various relevant classes of organics are presented in terms of chemical behavior and physical properties. In order to facilitate the discussion to follow, a few basic definitions will be presented first. 

Structural isomerism is common among all types of organic compounds. For example, there are... 

The deposition of a binary compound can be achieved by a coreduction reaction. In this manner, ceramic materials such as oxides, carbides, nitrides, borides, and silicides can be produced readily and usually more readily than the parent metal. A common example is the deposition of titanium diboride ... 

Examples of preservatives are phenylmercuric nitrate or acetate (0.002% w/v), chlorhexidine acetate (0.01 % w/v), thiomersal (0.01 % w/v) and benzalkorrium chloride (0.01 % w/v). Chlorocresol is too toxic to the comeal epithehum, but 8-hydroxyquinoline and thiomersal may be used in specific instances. The principal considerahon in relation to antimicrobial properties is the activity of the bactericide against Pseudomonas aeruginosa, a major source of serious nosocomial eye infections. Although benzal-konium chloride is probably the most active of the recommended preservatives, it cannot always be used because of its incompatibility with many compounds commonly used to treat eye diseases, nor should it be used to preserve eye-drops containing anaesthetics. Since benzalkonium chloride reacts with natural mbber, silicone or butyl rabber teats should be substituted. Since silicone mbber is permeable to water vapour, products should not be stored for more than 3 months after manufacture. As with all mbber components, the mbber teat should be pre-equilibrated with the preservative prior to... 

The first two are very soluble in water but the last is less so. Weaker bases include ammonium hydroxide where X is NH4. In fact every acid can generate a base by loss of a proton and the definition now includes any compound capable of donating electron pairs, e.g. amines. Bases turn litmus paper blue and show characteristic effects on other indicators. They are soluble in water, tarnish in air, and in concentrated form are corrosive to the touch. Common examples are given in Table 3.5. ... 

The second special case is addition of a very good nucleophile hydrogen cyanide and bisnllite are the most common examples, and cyanohydrins, a-cyanoamines and bisnllite addncts (a-hydroxy snlfonates) are commonly stable enough to isolate, at least for reactive carbonyl compounds. All these compounds are prone to fall apart nnder snitable conditions, regenerating the carbonyl compound. 

The most common example is decomposition of azo compounds, where —X—Y— is -N=N-.311 The elimination of nitrogen from cyclic azo compounds can be carried... 

Other common examples are aluminium chloride, tin(rv) chloride, zinc chloride, etc. We shall, at this point, be concerned essentially with proton acids, and the effect of structure on the strength of a number of organic acids and bases will now be considered in turn. Compounds in which it is a C—H bond that is ionised will be considered subsequently (p. 270), however. 

By far the most common examples of this are with derivatives of NH3, particularly those like HONH2, NH2CONHNH2, PhNHNH2, etc., which have long been used to convert liquid carbonyl compounds into solid derivatives, for their characterisation 2,4-dinitrophenylhydrazine, (N02)2C6H3NHNH2, is particularly useful in this respect. 

---