The Alcohols

Reaction with OH radicals is the dominant atmospheric loss process for the saturated alcohols while reactions with NO3,03, and photolysis are negligible. The OH-initiated reaction proceeds by H-atom abstraction from the various C— H bonds of the CH3, —CH2, and CH groups in the alkyl chain, and to a much lesser extent from the O—H bond. The available mechanistic data for the OH reaction with saturated alcohols show that H-atom abstraction from the a-carbon atom is an important reaction channel, with abstraction Irom the other positions also making a significant contribution to the 

This chapter contains kinetic and mechanistic information on the reactions of OH, NO3, O3, and Cl with saturated-, unsaturated-, halogenated-, and aromatic-alcohols, and alkyl hydroperoxides. The reactions of OH radicals with saturated alcohols presented here are based on the recent review by Calvert et al. (2008) with relevant updates. Rate coefficients are combined with the tropospheric concentrations of OH, NO3, and O3 to estimate atmospheric lifetimes of these compounds. 

Oh and Andino (2001) reported an increase of the rate coefficient by 30% in the presence of ammonium sulfate aerosols. However, Sprensen et al. (2002) conducted experiments which showed that the presence of 500-8,000 fj,g m of NaCl or NH4NO3 aerosols (levels which far exceed those found in the atmosphere) does not affect the reactivity of OH with methanol. Furthermore, Sprensen et al. (2002) showed that the effect reported by Oh and Andino (2001) is inconsistent with gas kinetic theory and hence is erroneous. 

The reaction of OH with CD3OH was studied by Greenhill and O Grady (1986) and McCaulley et al. (1989) at 298 K, and by Hess and Tully (1989) between 293 and 862 K. Greenhill and O Grady and Hess and Tully reported a kinetic isotope effect 

T Nelson et al. (1990a), Absolute Nelson et al. (1990a), Relative 

Methanol s major advantages in vehicular use are that it is a convenient, familiar liquid fuel that can readily be produced using well-proven technology. It is a fuel for which vehicle manufacturers can, with relative ease, design a vehicle that will outperform an equivalent gasoline vehicle and obtain an advantage in some combination of emission reduction and efficiency improvement [1.7]. 

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Figure 1 compares data reduction using the modified UNIQUAC equation with that using the original UNIQUAC equation. The data are those of Boublikova and Lu (1969) for ethanol and n-octane. The dashed line indicates results obtained with the original equation (q = q for ethanol) and the continuous line shows results obtained with the modified equation. The original equation predicts a liquid-liquid miscibility gap, contrary to experiment. The modified UNIQUAC equation, however, represents the alcohol/n-octane system with good accuracy. 

Borneol and isoboineol are respectively the endo and exo forms of the alcohol. Borneol can be prepared by reduction of camphor inactive borneol is also obtained by the acid hydration of pinene or camphene. Borneol has a smell like camphor. The m.p. of the optically active forms is 208-5 C but the racemic form has m.p. 210-5 C. Oxidized to camphor, dehydrated to camphene. 

CgH]2N202. Colourless crystals m.p. 171-172°C. Used as a sweetening agent, dulcitol, Calcohol from galac-... 

CH3CH2OHCH3. B.p. 82 C. Manufactured by hydrolysis of propene. Used in the production of acetone (propanone) by oxidation, for the preparation of esters (e.g. the ethanoate used as a solvent), amines (diisopropylamines, etc.), glycerol, hydrogen peroxide. The alcohol is used as an important solvent for many resins, aerosols, anti-freezes. U.S. production 1978 775 000 tonnes. 

D[Pg.367]

C,flH2o02- White crystals, m.p. 168-171 °C. Prepared from deoxyanisoin by ethylation, conversion to the alcohol, dehydration and demethylation. It is an oestrogenic substance which is highly active when administered orally. It is used for treating menopausal symptoms, for the suppression of lactation and for treatment of cancer of the prostate. 

Outside of hydrocarbons, certain organic oxygenated compounds such as the alcohols and ethers are henceforth utilized in the formulation of gasolines. These are mostly methanol, ethanol, propanols and butanols, as well as methyl and ethyl ethers obtained from and Cj olefins ... 

We have considered the surface tension behavior of several types of systems, and now it is desirable to discuss in slightly more detail the very important case of aqueous mixtures. If the surface tensions of the separate pure liquids differ appreciably, as in the case of alcohol-water mixtures, then the addition of small amounts of the second component generally results in a marked decrease in surface tension from that of the pure water. The case of ethanol and water is shown in Fig. III-9c. As seen in Section III-5, this effect may be accounted for in terms of selective adsorption of the alcohol at the interface. Dilute aqueous solutions of organic substances can be treated with a semiempirical equation attributed to von Szyszkowski [89,90]... 

Fig. III-9. Representative plots of surface tension versus composition, (a) Isooctane-n-dodecane at 30°C 1 linear, 2 ideal, with a = 48.6. Isooctane-benzene at 30°C 3 ideal, with a = 35.4, 4 ideal-like with empirical a of 112, 5 unsymmetrical, with ai = 136 and U2 = 45. Isooctane-

A familiar (and biblical [SO]) example is the formation of tears of wine in a glass. Here, the evaporation of the alcohol from the meniscus leads to a local raising of the surface tension, which, in turn, induces a surface and accompanying bulk flow upward. 

Referring to Fig. IV-4, the angles a and /3 for a lens of isobutyl alcohol on water are 42.5° and 3°, respectively. The surface tension of water saturated with the alcohol is 24.5 dyn/cm the interfacial tension between the two liquids is 2.0 dyn/cm, and the surface tension of n-heptyl alcohol is 23.0 dyn/cm. Calculate the value of the angle 7 in the figure. Which equation, IV-6 or IV-9, represents these data better Calculate the thickness of an infinite lens of isobutyl alcohol on water. 

Volatile boron compounds burn with a green flame. If a solid borate is mixed with methanol and concentrated sulphuric acid, the volatile compound boron trimethoxide, BfOCHj j, is formed and ignition of the alcohol therefore produces a green flame ... 

CH3COOH + HOC2H5 - CH3GOOC2H3 + H2O If, however, concentrated sulphuric acid is present, the water is absorbed, the back reaction prevented, and a high yield of ethyl acetate is obtained. In practice the reaction is not so simple. It was formerly supposed that, since the sulphuric acid is usually added to the alcohol, ethyl hydrogen sulphate and water are formed, the latter being absorbed by the excess of sulphuric acid, A mixture of ethanol and acetic acid is then added to the ethyl hydrogen sulphate,... 

I. Action of sulphuric add. To 0 5 ml. of the alcohol, add 0 5 ml. of cone. H2SO4 and shake the mixture. Heat is evolved and a white gelatinous polymer gradually separates. The reaction is hastened by warming and the product darkens. 

All esters are hydrolysed by sodium hydroxide to the alcohol (or sodium phenoxide) and the sodium salt of the acid from which they are derived. 

Dinitrobenzoates. The 3,5-dinitrobenzoate of the alcohol portion of the ester may be obtained by ester interchange. Thus an ester, R -COOR, when heated with 3,5 dinitrobenzoic acid and sulphuric acid gives (N03)2CgH3C00R. 

It should be noted that this test gives information only about the nature of the alcohol component of the original ester, whereas test 4 ( ) gives information about the acid component. 

C) i -Dinitrobenzoates (see 5 above) can usually be prepared directly from the ester, provided that the alcohol component is not destroyed too rapidly by hot sulphuric acid. (M.ps., pp. 546-548.)... 

NOTE. Many esters reduce Fehling s solution on warming. This reduction occurs rapidly with the alkyl esters of many aliphatic acids, but scarcely at all with similar esters of aromatic acids (f.g., ethyl oxalate reduces, but ethyl benzoate does not). Note also that this is a property of the ester itself thus both methyl and ethyl oxalate reduce Fehling s solution very rapidly, whereas neither oxalic acid, nor sodium oxalate, nor a mixture of the alcohol and oxalic acid (or sodium oxalate), reduces the solution. 

A) (i) Distillate. Test for the alcohol. e.g., methyl, ethyl, benzyl, or cyclohexyl alcohol. 

Method. A known weight of the alcohol is heated w ith a definite volume of a mixture of acetic anhydride and pyridine until acetylation is complete ... 

The excess of unchanged acetic anhydride is then hydrolysed by the addition of water, and the total free acetic acid estimated by titration with standard NaOH solution. Simultaneously a control experiment is performed identical with the above except that the alcohol is omitted. The difference in the volumes of NaOH solution required in the two experiments is equivalent to the difference in the amount of acetic add formed, i.e., to the acetic acid used in the actual acetylation. If the molecular weight of the alcohol is known, the number of hydroxyl groups can then be calculated. 

Note, (i) It fs clear that the molecular weight of the alcohol or phenol must be known before the above determinations are carried out. The molecular weight if unknown must be determined by one of the methods gii en on... 

Since an enzyme is a biological catalyst and therefore merely accelerates a reaction, it cannot alter the position of equilibrium in a reversible reaction. The hydrolysis of p-methylglucoside is reversible and emulsin should therefore be capable also of synthesising this compound frc n glucose and methanol. This synthesis can actually be carried out by the action of the enzyme on glucose dissolved in an excess of methanol, the excess of the alcohol throwing the equilibrium over to the left. Owing to experimental difficulties, this reaction is not here described. 

An important application of the critical solution temperature is to the determination of the water content in such substances as methyl and ethyl alcohols. Here the system is usually the alcohol and a hydro carbon, such as -hexane or dicyclohexyl the water is, of course, insoluble in the hydrocarbon. Thus, the methyl alcohol - cyclohexane system has a C.S.T. of 45 -5° and even 0 01 per cent, of water produces a rise of 0-15° in the C.S.T. The experimental details are given below. 

For methyl alcohol, two volumes of synthetic n-hexane, b.p. 68-6-69 0° (uncorr.), and one volume of the alcohol to be tested are mixed and the homogeneous mixture is cooled in ice until the appearance of a cloudiness. A thermometer is placed in the solution, which is allowed to warm gradually to the temperature at which the second phase disappears. The... 

For ethyl alcohol, two volumes of dicycZohexyl are mixed with one volume of the alcohol, a thermometer is introduced, and the mixture heated until it becomes clear. The solution is then slowly cooled, with constant stirring, and the temperature is determined at which the opalescent solution suddenly becomes turbid so that the immersed portion of the mercury thread of the thermometer is no longer clearly visible. This is the C.S.T. The water content may then be evaluated by reference to the following table. 

In practice, it is best to purify a quantity, say one Winchester quart bottle, of technical 0 720 ether to cover the requirements of a group of students. The Winchester quart of ether is divided into two approximately equal volumes, and each is shaken vigorously in a large separatory funnel with 10-20 ml. of the above ferrous solution diluted with 100 ml. of water. The latter is removed, the ether transferred to the Winchester bottle, and 150-200 g. of anhydrous calcium chloride is added. The mixture is allowed to stand for at least 24 hours with occasional shaking. Both the water and the alcohol present are thus largely removed. The ether is then filtered through a large fluted filter paper into another clean dry Winchester bottle (CAUTION all flames in the vicinity must be... 

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