Solvent organic

Organic solvents, which induce CYP2E1, are comprised of a few broad chemical classes, including hydrocarbons such as benzene and toluene, halogenated aliphatic compounds such as carbon tetrachloride and dichloroethane, aliphatic alcohols such as ethanol, and hydroxyethers such as 2-methoxyethanol. Industrial solvents are frequently mixtures of several compounds. The most frequent solvent-associated toxicity occurs from occupational exposure. A number of organic solvents have been examined for their effects on the immune system, and the requirement for their bioactivation to produce immunotoxicity has been well established. 

TABLE 32.6. Some Mechanisms Associated with Immune Suppression 

Inactivation of calcineurin disrupting signals needed for IL-2 gene transcription 

Covalent binding to DNA disrupting replication, cell proliferation, and function leading to cytotoxicity 

Same as above targeting bone marrow progenitor cells 

2 Organic Solvents. Sensitivity in flame atomic absorption and plasma emission is often significantly better in organic solutions than in aqueous solutions. In Table 43 sensitivities are compared for copper, cadmium, and antimony in various organic solvents with those in aqueous solutions measured by flame atomic absorption. 

In FAAS an ideal organic solvent should possess the following characteristics (i) Low viscosity (ii) Good combustion characteristics (low background absorption and nontoxic combustion products) (iii) Low volatility (iv) Immiscibility in water (v) Not poisonous (vi) Good extraction efficiency (vii) Good nebulization efficiency (viii) Easy to handle (ix) Available in high purity form. 

Volatile solvents (methanol, acetone, diethyl ether) will vaporize significantly before meeting the flame. The expanded vapour increases the flow rate of the gases in the mixing chamber by increasing the burning velocity and causes an erratic response. Aromatic compounds and halides are also 

The most suitable solvents are Ce or C7 aliphatic esters or ketones and Cio alkanes. The most common organic solvent in FAAS is 4-methyl-2-pentanone (MIBK = methyl isobutyl ketone). Its nebulization, combustion, and volatilization properties are good for spraying into the flames. Its solubility in water is relatively high (2.15 ml per 100 ml H2O at 30 °C). In addition, its solubility significantly depends on the temperature and the ionic strength of the aqueous phase. The solubility of MIBK in water may be reduced and extraction efficiency increased with addition of amyl acetate (1 10 v/v) or cyclohexane (1 4 v/v). Other solvents commonly used are ethylacetate, butylacetate, and ethylpropionate. 

In practice, organic solvents increase the amount of combustion compounds in the flame and, because of that, the ratio between the fuel and oxidant gases must always be optimized when organic solvents are sprayed directly into the flame. The flow rate of the fuel gas and the sample intake may be decreased or the flow of the oxidant increased. 

Several organic solvents have also been employed for SEC of proteins under denaturing conditions. Swergold and Rubin (22) have described a system employing a TSK 3000PW column eluted with 36-45% acetonitrile In 0.1% trlfluoroacetlc acid (TFA). The protein resolution observed In this eluant Is markedly dependent on acetonitrile concentration and requires the low pH provided by TFA. The authors report that under optimum conditions, a linear fractionation range Is observed with proteins and peptides ranging from 300-130,000 Da. 

The volatile nature and ultraviolet transparency of the acetonitrlle-TFA eluant appear to make It an attractive candidate for protein SEC. However, we have found that a serious limitation of the system Is the low solubility of proteins of greater than about 15 kDa In 30-45% acetonitrile required for optimum resolution. This poor solubility results in severe protein aggregation problems, apparently limiting the usefulness of this system to peptides and very low molecular weight proteins. 

Gruber et al. (39) reported that proteins ranging In molecular weight from 5-70 kDa could be separated on a GPC-lOO column eluted with O.IM formic acid, pH 2.35. Although the precise value was not determined, the authors did report a linear calibration curve over the molecular weight range tested. 

The first example of principal properties for synthetic experiments was PC analysis of a set of 82 solvents, characterized by eight property descriptors [55]. The analysis was carried out with a view to finding rational principles for selecting test solvents for new reactions. Principal properties of solvents have now been determined from an augmented data set of 103 solvents characterized by nine descriptors [56]. A score plot is shown in Sect. 5.3.2 in the example on the Fischer indole synthesis. 

Several PCA studies on solvents have been reported [57], However, the objectives in these studies have been either to make classifications or to elucidate physical-chemical relations, and not explicitly to assist in synthetic experimentation. A discussion on multivariate studies on solvents is given in the book by Reichardt [58], 

There are certain accepted tests used to determine the extent to which a given organic pigment tolerates solvents. Experimental procedures commonly involve 

The way in which a pigment behaves toward a specific solvent has a considerable impact on how it can be employed by the user. If a pigment which is partially soluble in a solvent is processed in a system containing that solvent, then recrystallization may occur. This in turn alters the coloristic, rheological, and fastness properties of the product. 

A number of potential users, such as the printing industry, are interested in the solvent fastness not only of a pigment but of an entire pigment-vehicle system. Standardized tests are available. A proof print of a certain size is placed inside a test tube and allowed to remain in the target solvent at 20°C for 5 minutes. The change in solvent color is determined and the print dried and compared with an untreated specimen. Standard solvents [14] are ethanol or the following mixture  

However, the results do not necessarily reflect the fastness to overlacquering in actual application, because overprint varnishes may contain other solvents as well. Besides, a series of additional factors such as the effect of plasticizers, uneven flow of the pigmented lacquer, etc., play a role in pigment performance. The fastness to overlacquering is therefore most realistically determined in actual application. 

Pigment performance also includes fastness to transparent lacquer coatings ( silver lacquer ), that is, fastness to transparent enamels which are applied to metal deco prints to give them rub and scratch fastness. 

Disposal. Acetone and alcohol can be saved for future cleaning, or recovered by distillation. None of the halogenated hydrocarbons should ever be poured down the sink. If poured on a rag to wipe a stopcock, you may be able to leave the rag in a fume hood to dry before disposing of the rag. However, such a rag may classify as a toxic waste and may require special handling and disposal. There are many laws that govern the disposal of organic solvents, so check with the safety coordinator where you work for specific information. 

However, there are disadvantages to the base bath. First, it has some safety hazards. The alcohol is a potential fire hazard, and the bath s alkalinity is caustic to skin. The base bath is also a mild glass stripper. That is, instead of cleaning the glassware, it actually removes layers of glass (and any adjoining contamination). 

Therefore, glassware should not soak in a base bath for an extended period of time, and the base bath should never be used for volumetric ware. 

Material. Sodium hydroxide (NaOH) or potassium hydroxide (KOH) and ethyl alcohol. 

Preparation. Mix one liter of 95% ethyl alcohol with a solution of 120 g of NaOH (or KOH) mixed in 120 mL of water. 

Fewer solubilities are recorded for ethanol-sugar systems. Trey80 found the solubility of D-glucose in ethanol to be 0.25% w/v at 20° 

Reactions of the sugar with the alcohol group of the solvent are confined to glycoside formation, a reaction catalyzed by acids ranging from mineral acids to insoluble ion-exchangers.114-116 A general review by Shafizadeh117 describes the earlier work. Bishop and cowork- 

Methyl a-D-glucopyranoside is the only product of commercial promise to have thus far emerged from work with protic solvents it has utility in the preparation of polyurethane foams. Mehltretter and coworkers125,126 have described the application of mixtures of D-glucosides obtained by the acid-catalyzed reaction of ethylene glycol, 1,2-propanediol ( propylene glycol ), or glycerol with starch, 

Incidental reactions that have been reported include the preparation of derivatives of 5-(hydroxymethyl)-2-furaldehyde by reaction of D-fructose in acetic or propionic acid in the presence of the respective anhydride.158 The condensation of D-glucose with phenol has been effected in acetic acid in the presence of dry hydrogen chloride, prior to resinification,157 and the reaction of sucrose with thionyl chloride in acetic acid-acetic anhydride produced partially acetylated chlorodeoxysucroses.158 Sucrose has been condensed with maleic anhydride in acetic anhydride mixed with acetic acid or formic acid, to give solid products having an undetermined structure.159 

A rather unusual solvent system for sucrose, namely, molten chloroacetic acid, was used by Lorand,160 who prepared sucrose esters from palmitic anhydride dissolved in this medium. It is unlikely that the glycosidic link in the sucrose is unaffected under these conditions. 

Lighter fuels, benzene, toluene, cleaning fluids (carbon tetrachloride), petrol, paraffin, and even the fluorocarbon propellants found in various household sprays and medications have all been used, particularly by children, to produce changes in consciousness. They are all inhaled, often with the aid of a plastic bag, and, since they are lipid-soluble, they are readily concentrated in brain tissue. As with many anesthetics there is an early period of hyperactivity, excitement, and intoxication, followed by sedation and confusion. Prolonged or regular use can cause serious toxicity, with bone-marrow depression, cardiac dysrhythmias, peripheral neuropathy, cerebral damage, and liver and kidney disorders (1). 

Many organic solvents are used in pharmaceutical products. These include propylene glycol, polyethylene glycols, ethanol, dimethyl sulfoxide, N-methyl-2-pyrrolidone, glycofurol, Solketal, glycerol formal, and acetone evidence of harm from such solvents is scant (2). 

Much of the information about the harmful effects of organic solvents comes from studies of industrial exposure, although toluene abuse through sniffing of glues and other household sources of solvents (acrylic paints, adhesive cements, aerosol paints, lacquer thinners, shoe polish, typewriter correction fluids, varnishes, and fuels) has also been widely reported. 

The epidemiology of inhalant abuse has been widely studied in the USA (3). There is no overall sex difference in solvent abuse, although girls are more likely to be users in younger age groups and boys in older ones. Inhalant abuse is more common among school dropouts. Native Americans and Hispanic Americans are over-represented and blacks under-represented. 

In the UK 3.5-10% of children under 13 years have abused volatile substances, and 0.5-1% are long-term users (3). In 1980 24 cases of solvent abuse were reported in Singapore, but by 1984 the number had increased to 763 and from 1987-91, 1781 glue sniffers were identified. In 2004, it was reported that street children in India were abusing typewriter eraser fluid, which contains toluene. In low-income families in Sao Paulo, Brazil, 24% of children had inhaled a volatile substance at some time and 4.9% had inhaled within the last month. 

Despite the efficiency of the manufacture of ethanol from petrochemical feedstocks, much of the world s production is based on a fermentation process. Over the past 75 years in the United States, where the total annual production now stands at just under 4 million tonnes, the source of this basic chemical feedstock has swung away from fermentation to petrochemistry and back again (Table 6.1). The carbon source for the fermentation is glucose derived from starch (see Section 6.6). An even larger quantity, about 9.5 million tonnes, is produced each year in Brazil from cane sugar. Nowadays the prime consumer is the motor car. 

Economic, political and social pressures have influenced the manufacture of ethanol since the fermentation process was introduced many years ago (see Chapter 1). In the nineteenth century its status as an industrial solvent was assured when industrial methylated spirit, which is ethanol denatured with methanol to make it unfit for human consumption, was freed from excise duty. In the twentieth century, the social and political pressures which provide economic support for agriculture have allowed fermentation to compete effectively with petrochemistry as a manufacturing process. The technical achievements in chemistry, biology and engineering have only facilitated the switch between carbohydrate and oil as feedstock for the process. 

T able 6.1. Proportion of ethanol which is manufactured byfermentation in the United States 

The microbiological method soon found itself in competition with the growing petrochemical industry, and in the United Kingdom the use of fermentation for acetone manufacture was stopped in 1957. However, the method is still used in some parts of the world, notably in China, where oil is in short supply. Given the present dominance of fermentation in the ethanol market in the United States, it would not be surprising to see some of their current needs for acetone, butan-l-ol and propan-2-ol production (Table 6.2) being supplied by a return to fermentation. 

Supercritical Fluids Technology in Lipase Catalyzed Processes 

Short alcohols, which are the other substrates, have poor solubility in triglycerides, and when they are present as insoluble droplets in the organic phase, they strip the essential water molecules from the enzyme, resnlting in deactivation (Shimada et al., 1999). This is further discussed in Chapter 6. 

On the other hand, from an environmental point of view, the use of organic solvents has to be minimized because of their negative environmental impact. In addition, the use of organic solvents is generally not acceptable in the food and pharmaceutical industries (Ikeda, 1992 Snyder et al., 1996). Furthermore, they are usually expensive and require separation from the reaction medium. The need for better technology with higher purity and environmentally friendly processes 

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In the commercial extraction of alkaloids from the drugs in which they exist, the powdered drug, or an alcoholic extract of it, is treated with an alkali such as ammonia or lime to liberate the alkaloid and the alkaloid is then extracted by means of an organic solvent. The crude material thus obtained is purified and finally crystallized either as the base itself or as its water-soluble salts. 

C HjCla, PhCCla. Colourless liquid, b.p. 2I3-214" C. Insoluble in water, miscible with organic solvents. 

C8H10N4O2. An alkaloid occurring in tea, coffee and guarana, from which it may be prepared by extraction, It is also manufactured by the methylation of theobromine and by the condensation of cyanoacetic acid with urea. Crystallizes with H2O or anhydrous from organic solvents. M.p. (anhydrous) 235"C, sublimes at 176 C. Odourless, and with a very bitter taste. Caffeine acts as a stimulant and diuretic, and is a constituent of cola drinks, tea and coffee. 

Copper(I) perchlorate, CUCIO4. Formed in solutions of organic solvents (Et20, C Hf,) by displacement of Ag by Cu. 

Insoluble in water, soluble in organic solvents b.p. — 15°C. Prepared by treating 1,4-dibromo-butane with metallic sodium. Reduced to n-butane by hydrogen at 200" C in presence of nickel catalysts. 

The lower members of the series are liquids soluble in water and volatile in steam. As the number of carbon atoms in the molecule increases, the m.p. and b.p. rise and the acids become less soluble in water and less volatile. The higher fatty acids are solids, insoluble in water and soluble in organic solvents. 

C. Insoluble in water, soluble in organic solvents. Flavone occurs naturally as dust on the flowers and leaves of primulas. It has been prepared from o-hydroxyacetophenone and benzaldehyde. 

While solid m.p. 95 -96 - C, soluble in organic solvents. An insecticide similar to chlordane. Used to control cotton boll weevil. 

Karathane A trade name for 2,4-dinitro-6-( 1 -methylheptyl)phenyl crotonate, CJ8H24N2O6, a compound which has both acaricidal and fungicidal activity. It is a red-brown oil of high boiling point, insoluble in water but soluble in most organic solvents. Karathane is used for the control of powdery mildew, and is nontoxic to mammals. 

The most common of the xanthophyll pigments, it is present in all green leaves, in blossoms and in various animal sources. It crystallizes in violet prisms with one molecule of methanol m.p. I93 C, soluble in organic solvents giving yellow solutions, li is related to a-carolene in the same way as zeaxanlhin is to /1-carolene. 

It is manufactured by heating dicyandiamide, H2N C(NH) NH CN, either alone or in the presence of ammonia or other alkalis, in various organic solvents. Melamine is an important material in the plastics industry. Condensed with melhanal and other substances it gives thermosetting resins that are remarkably stable to heat and light. U.S. production 1980 80 000 tonnes. 

Siher I) fluoride, AgF, is prepared by evaporation of a solution of excess Ag20 in HF after filtration or by heating anhydrous AgBF. The anhydrous salt is yellow hydrates are known, It is very soluble in water and in many organic solvents. Used as a mild fluorinating agent. On treatment of a solution with Ag a sub-fluoride, Ag2F, is formed. 

Substances are generally soluble in like solvents. Organic molecules in molecular solvents such as CCI4, C2H5OH, ether, propanone. Inorganic salts are often soluble in water and less soluble in organic solvents. 

Sydnones are neutral, highly crystalline, stable compounds, soluble in most organic solvents. N-Arylsydnones typically are obtained by treating N-nitroso-N-aryl-glycines with etha-noic anhydride. The parent glycine is regenerated when the sydnone is heated with dilute alkali. 

Tin IV) chloride, SnCU, stannic chloride. M.p. — 33" C, b.p. 1I4°C. Colourless fuming liquid (Sn plus CI2) hydrolysed in water but forms SnCl4,5H20 and [SnCl p" from acid solutions, soluble in organic solvents. Used as a mordant. 

The sample to be analyzed can be dissolved in an organic solvent, xylene or methylisobutyl ketone. Generally, for reasons of reproducibility and because of matrix effects (the surroundings affect the droplet size and therefore the effectiveness of the nebulization process), it is preferable to mineralize the sample in H2SO4, evaporate it and conduct the test in an aqueous environment. 

Al-Obaidi A H R, Rigby S J, Hegarty J N M, Bell S E J and McGarvey J J 1996 Direct formation of silver and gold metal liquid-like films (MELLFS) from thiols and sols without organic solvents SERS and AFM studies ICORS 96 XVth Int. Conf on Raman Spectroscopy ed S A Asher and P B Stein (New York Wiley) pp 590-1... 

Luminescence has been used in conjunction with flow cells to detect electro-generated intennediates downstream of the electrode. The teclmique lends itself especially to the investigation of photoelectrochemical processes, since it can yield mfonnation about excited states of reactive species and their lifetimes. It has become an attractive detection method for various organic and inorganic compounds, and highly sensitive assays for several clinically important analytes such as oxalate, NADH, amino acids and various aliphatic and cyclic amines have been developed. It has also found use in microelectrode fundamental studies in low-dielectric-constant organic solvents. 

The majority of practical micellar systems of Tionnal micelles use water as tire main solvent. Reverse micelles use water immiscible organic solvents, altlrough tire cores of reverse micelles are usually hydrated and may contain considerable quantities of water. Polar solvents such as glycerol, etlrylene glycol, fonnamide and hydrazine are now being used instead of water to support regular micelles [10]. Critical fluids such as critical carbon dioxide are... 

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