Orcin, CH(CH,)(OH)2, is a dioxy-toluene. It is found in many lichens (Rocella tinctoria, Lecanora, etc.). It is formed when aloes are fused with caustic potash, and can be made synthetically from toluene, by fusing m-dibrom-toluene with potash at 280°. It crystallizes in colorless prisms, which turn red. The ammoniacal solution absorbs oxygen from the air, and yields orcein, C,H,NO,, the chief constituent of commercial archil dye. Related to this latter coloring matter is also litmus, the wellknown blue vegetable color.

one of

Homo-pyrocatechin, CH(CH)(OH)2, is an isomeric dioxytoluene. Its methyl-ether is creosol, CH,(CH3), {OCH, the chief constituents, along with guaiacol, of the creosote of beech-wood-tar.

Eugenol, the chief constituent of oil of cloves, is the methylether of an unsaturated phenol, CH(OH),(CH2.CH=CH2).

3. Triatomic Phenols.-Of the three isomeric trioxy-benzenes, the most important is Pyrogallol, CH(OH), (Pyrogallol, U. S. P.). It is obtained generally by the dry distillation of gallic acid : CH2(OH),COOH = С ̧H ̧(OH), + CO. It forms light, white, shining laminæ, odorless, and with a bitter taste. It becomes darker on exposure to air and light. It is soluble in water, alcohol, and ether. Its solutions, especially when alkaline, absorb oxygen from the air and turn brown in color. Because of this reaction it is used in gas analysis to absorb free oxygen from gaseous mixtures. This reducing power is also recognized with silver, gold, and mercury solutions. It is largely used in photography as a developer because of this power of reduction of silver salts. Pyrogallol also combines with phthalic anhydride to form the dye-color "galleïn."

Phloroglucin, CH(OH) ̧, an isomeric trioxy-benzene, is produced in the decomposition of phloretin, a glucoside, and by the fusion of a number of resins (such as gamboge, dragon's blood, catechu, and kino) with caustic potash. It is also obtained synthetically by the fusion of benzene-trisulphonic acid with potash. It forms large prisms, which sublime without decomposition, melting at 218°. With ferric chloride it gives a dark-violet coloration. Phloroglucin colors a pine shaving, moistened with hydrochloric acid, red, and is used for the detection of lignin or wood-fibre in paper, etc.

Oxyhydro-quinone, CH,(OH),, the third isomeric trioxy-benzene, results from the fusion of hydro-quinone with potash.

4. Tetratomic Phenols.-A tetroxy-benzene, CH,(OH), has been prepared from succino-succinic ether. It crystallizes in yellow needles, and is stable when pure.

5. Pentatomic Phenols.-As hexahydro derivatives of a pentatomic phenol, C.H(OH),, we must include several compounds which at one time were considered to be pentatomic alcohols, or to belong to the carbohydrates.

Quercite, CH(OH). H.-A sweet-tasting crystalline principle extracted from the oak. It forms colorless monoclinic crystals, melting at 235°.

Pinite, CH(OH). Hg, is found in the exudation of the California pine (Pinus lambertiana). It forms colorless crystals, easily soluble in water, and fusing at over 150°.

Inosite (Phaseomannite), CH12O + 2H2O, is found in small amount in the muscular tissue, in the heart, lungs, liver, spleen, kidneys, and brain; the urine also contains inosite after abundant water drinking.

It is also contained in plants, as green beans, peas, lentils, and grape juice. It crystallizes in rhombic plates, which crumble in the air. Soluble in water, insoluble in alcohol. Melts at 210°. It has no reducing power, nor is it fermentable.

6. Hexatomic Phenols.-We have a derivative of the normal hexaoxy-benzene, С(OH), in the so-called potassium carbon monoxide, formed in the distillation of metallic potassium, which has the formula C.(OK). The phenol itself has also been prepared synthetically. It forms small, grayish-white needles, which acquire a reddish color on exposure to the air. They are not fusible, but decompose at about 200°.

Phenose is a hexatomic phenol of hexahydro-benzene, and has the formula CH(OH). It has been obtained by the action of soda solution upon the hypochlorous acid addition product of benzene, CH(OH), It is an amorphous, readily soluble, and deliquescent substance. It is much like the glucoses, has a sweet taste, and reduces Fehling's solution, but is not capable of fermentation.

7. Quinones. This term is applied to a class of benzene derivatives in which two hydrogen atoms seem to be replaced by two oxygen atoms. Not only benzene, but especially the condensed aromatic hydrocarbons, naphthalene, anthracene, phenanthrene, chrysene, etc., when oxidized by chromic acid in glacial acetic acid solution, yield quinones. They are formed also by the oxi

dation of a number of derivatives of benzene in which the replacing groups occupy the para position. Thus, hydro-quinone (paradioxy-benzene), sulphanilic acid (p-amido-benzene-sulphonic acid), and phenylene-diamine, as well as phenol and aniline, all yield quinone when oxidized by chromic acid.

The constitution of quinone, CH,O,, is not definitely settled. O By some it is written C.H.{O> and by others C.H

CO

or

would be a peroxide, according to the second a ketone, not of benzene itself, but of a dihydro-benzene. This latter view is now generally accepted, as it brings it into analogy with anthraquinone and the other higher quinones which are known to be diketones.

Quinone (Benzo-quinone), CHO2, is made most readily by oxidizing aniline sulphate with chromate of potash and sulphuric acid. The quinone so formed is shaken out with ether. Yellow prisms melting at 115.7° and subliming. It has a chlorine-like odor, is difficultly soluble in cold water, more readily soluble in hot water, as well as in alcohol and ether. It is easily converted into hydroquinone by reducing agents like SO, or HI.

By chlorinating quinone, or by the action of potassium chlorate and hydrochloric acid upon phenol, we obtain tetrachlor-quinone (chloranil), CCO,. As reducing agents convert it readily into tetrachlorhydro-quinone, it is used as an oxidizing agent in the manufacture of aniline colors, as with methyl-violet. Several of the homologues of quinone may also be mentioned, as Toluquinone, CH,(O2)(CH,), Xylo-quinone, CH,(O,)(CH,), and

2

Thymo-quinone, C2H2O2) {CH,;

VIII.

AROMATIC ALCOHOLS, ALDEHYDES, AND KETONES. 1. Aromatic Alcohols.-The aromatic alcohols differ, as before stated, from the phenols in that the OH has replaced hydrogen in the side-group instead of hydrogen in the nucleus. They may be, and often are, isomeric with phenols, as benzyl alcohol, CH.CH2OH, and cresol, CH(CH ̧).OH.

The comparison of the formula of benzyl alcohol with that of the alcohols of the methane series will make its nature clearer :

H.CH2OH

Methyl Alcohol.

CH,.CH2OH
Ethyl Alcohol.

CH.CH2OH.
Benzyl Alcohol.

It is seen here that the single hydrogen of methyl alcohol is replaced by the radical methyl in the second formula, and by the radical phenyl, CH, in the third formula. Benzyl alcohol is therefore sometimes called phenyl-carbinol.

Just as in the methane series of alcohols we have primary, secondary, and tertiary, so we may have primary, secondary, and tertiary aromatic alcohols, as

Diatomic and triatomic alcohols likewise can be formed, as CH(CH2OH), toluyiene alcohols, and C,H,(OH),, stycerine alcohol.

The strongest analogy of these aromatic alcohols with the corresponding compounds in the methane series is found in the similarity in the effect of oxidizing agents. The primary aromatic alcohols yield aldehydes and monobasic acids, and the secondary yield ketones. Ethers, esters, mercaptans, amines, etc., are also formed in strict analogy to those already studied under the methane series. By the entrance of the phenyl group into unsaturated fatty alcohols we also obtain unsaturated aromatic alcohols analogous to other unsaturated compounds.

Benzyl Alcohol, СH.CH2OH, is found as benzoic and cinnamic esters in Peru and Tolu balsams, and is made from benzyl chloride, CH,CH,Cl, by boiling it for a time with water, or by the action of potash solution upon its aldehyde, CH.COH :

2CH. COH + KOH Benzaldehyde.

CH.CH2OH + CH.COOK.
Benzyl Alcohol.

Potassium Benzoate.

Benzyl alcohol is a colorless liquid of weak aromatic odor, boiling at 206.5°. It is not very soluble in water. When oxidized it yields first benzaldehyde, CH,. COH, and then benzoic acid, CH,.COOH.

Tolyl Alcohols, CH(CH)CH2OH.-All three isomeric varieties have been obtained.

Phenyl-methyl Carbinol, CH. CHOH.CH,, is a secondary alcohol obtained by the action of sodium amalgam upon the cor

responding ketone, CH.CO.CH, (acetophenone), and on careful oxidation reproduces this compound.

Phenyl-propyl Alcohol (Hydrocinnamyl Alcohol), СH.CH.CH.CH2OH, is obtained from cinnamyl alcohol by reduction. It exists as cinnamic ester in storax. Closely related to this is the unsaturated aromatic alcohol, known as

Cinnamyl Alcohol (Styrene), CH ̧.CH=CH.CH2OH.—This occurs as cinnamic ester under the name of styracine in storax resin (Styrax, U. S. P.). It crystallizes in shining needles, is sparingly soluble in water, and possesses a hyacinth-like odor. It melts at 33° and distils at 250°. On careful oxidation it yields cinnamic acid; more energetically oxidized it yields benzoic acid. 2. Aromatic Aldehydes.-These correspond in all their general properties with the aldehydes of the methane series.

Benzaldehyde, CH. COH (Oleum Amygdalæ Amaræ, U.S. P.) This compound was at one time exclusively obtained by the decomposition of the glucoside amygdalin of the bitter almond in the presence of emulsin and other ferments, according to the reaction C0H27NO11 + 2H,O=C,H,. COH+2C8H120, + HCN. It is now mostly made artificially by the oxidation of the chlorine derivatives of toluene :

2CH CH2Cl+CH,CHCl2+ 2MnO, 3CH5.COH + 2MnCl2 + H2O, Benzyl Chloride. Benzal Chloride. Benzaldehyde.

or by heating benzal chloride with milk of lime under pressure. This reaction has been already noted under benzal chloride (see p. 691).

Benzaldehyde is a colorless, strongly-refracting liquid of pleas ant bitter-almond odor. Boils at 179°, and has a sp. gr. of 1.05. It is only slightly soluble in water, but is easily soluble in alcohol and ether. Its behavior shows in many ways its character as an aldehyde. It is easily oxidized to the corresponding acid; it reduces silver solutions with the formation of a metallic mirror; it may be reduced to a primary alcohol; it forms a crystalline compound with sodium bisulphite; it reacts with hydroxylamine and phenyl-hydrazine. A reaction which is distinct and quite characteristic of it as an aromatic aldehyde is its power to unite to form condensation products. Thus, we are able to effect the synthesis of cinnamic acid by the condensation of benzaldehyde and sodium acetate, CH,.COH + CH,COONa = C,H,CH=CH.. COONa + H2O, a reaction of the greatest importance in the manufacture of artificial indigo (see Indigo).