Benzaldehyde

“ If it is found to contain sufficient benzoic acid to react with a considerable proportion of the sodium alcoholate, a poor yield of ester will be obtained. Less than 1 per cent of benzoic acid will not interfere seriously with the yields obtained, but the presence of larger quantities of acid will be found to be detrimental and must be removed by washing the benzaldehyde with a sodium carbonate solution and redistilling with the precautions necessary to prevent too free an access of air to the distillate. ”

“ On nitration it yields chiefly meta-nitro-benzaldehyde, crystallizing in needles which melt at 58° C. The ortho-compound may be obtained by oxidizing ortho-nitrocinnamic acid with alkaline potassium permanganate in the presence of benzene; or from ortho-nitrobenzyl chloride by condensing it with aniline, oxidizing the product so obtained to ortho-nitrobenzylidine aniline, and then hydrolysing this compound with an acid (Farben fabrik d. Meister, Lucius und Brüning) . ”

“ In making the acid by this process benzaldehyde, acetic anhydride and anhydrous sodium acetate are heated for some hours to about 1800 C, the resulting product is made alkaline with sodium carbonate, and any excess of benzaldehyde removed by a current of steam. The residual liquor is filtered and acidified with hydrochloric acid, when cinnamic acid is precipitated, C6H5CHO+CH3COONa = C6H5CH:CH.COONa + H2O. It may be purified by recrystallization from hot water. ”

“ Benzoic acid crystallizes in glistening leaflets (from water) which melt at 121·4° C. and boil at 249·2° C. (H. Kopp) . Its specific heat is 0·1946. It sublimes readily and is volatile in steam. It is readily soluble in hot water and the ordinary organic solvents, but is only slightly soluble in cold water. When heated with lime, it is decomposed, benzene being formed; if its vapours are passed over heated zinc dust, it is converted into benzaldehyde (A. Baeyer, Ann. 1866, 140, p. 296) . Distillation of its calcium salt gives benzophenone (q.v.) ”

“ The classical investigation of Liebig and Friedrich Wohler on the radical of benzoic acid (“Über das Radikal der Benzoë-säure,” Ann. Chem., 1832, 3, p. 249) is to be regarded as a most important contribution to the radical theory, for it was shown that a radical containing the elements carbon, hydrogen and oxygen, which they named benzoyl (the termination yl coming from the Gr. ὔλη, matter) , formed the basis of benzaldehyde, benzoic acid, benzoyl chloride, benzoyl bromide and benzoyl sulphide, benzamide and benzoic ether. ”

“ But the most important fact is that ammonium benzoate is largely used—often in combination with urinary anodynes such as tincture of hyoscyamus—as a urinary antiseptic in cases of cystitis (inflammation of the bladder) and pyelitis (inflammation of the pelvis of the kidney) .
BENZOIN, C6H5CHOH·CO·C6H5, a ketone-alcohol, which may be prepared by boiling an alcoholic solution of benzaldehyde with potassium cyanide; by reducing benzil (C6H5CO·CO·C6H5) with zinc and acetic acid; or by the oxidation of hydrobenzoin (C6H5-CHOH-CHOH-C6H5) . ”

“ It occurs naturally in some resins, especially in gum benzoin (from Styrax benzoin) , in dragon’s blood, and as a benzyl ester in Peru and Tolu balsams. It can be prepared by the oxidation of toluene, benzyl alcohol, benzaldehyde and cinnamic acid; by the oxidation of benzene with manganese dioxide and concentrated sulphuric acid in the cold (L. Carius, Ann. 1868, 148, p. 51) ; by hydrolysis of benzonitrile or of hippuric acid; by the action of carbon dioxide on benzene in the presence of aluminium chloride (C. Friedel and J.M. Crafts, Ann. chim. phys. 1888 [6] , 14, p. 441) ”

“ It has to be carefully protected from air and light and kept in well-closed bottles in a dark place. The crude oil, containing from 2 to 5 per cent. prussic acid, has generally a yellowish color.
Oil of bitter almonds may be prepared artificially in many ways. By allowing chlorine to flow into boiling toluene, the latter is converted into benzyl chloride:-
By withdrawing the chlorine and one atom hydrogen from the benzyl chloride and introducing for it one atom oxygen, the benzyl chloride is converted into benzaldehyde. ”

“ Bitter almond oil, which by oxidation yields benzoic acid, is wanting in benzoin. Very little volatile oil is in fact to be got; half a pound of the best Penang benzoin yielded us by distillation with water only a few drops of an extremely fragrant oil (styrol?) .
Ferric chloride imparts to an alcoholic solution of benzoin a dark brownish green, which is not acquired under the same circumstances by the aqueous decoction of the powdered resin. Benzoin dissolves in cold oil of vitriol, forming a solution of splendid carmine hue, from which water separates crystals of benzoic acid. ”

“ Benzoin is not manifestly acted on by bisulphide of carbon, but if kept in contact with it for a month or two, very large colourless crystals of benzoic acid make their appearance. Brought into a warm room, the crystals quickly dissolve, but are easily reproduced by exposure to cold.
Most pharmacopœias require not the inodorous acid obtained by a wet process, but that afforded by sublimation, which contains a small amount of fragrant empyreumatic products. The resin, when repeatedly subjected to sublimation, affords as much as 14 per cent. ”

“ When heated, these white specks rise as a smoke, which is easily condensed upon paper. The material thus separated from the benzoin is called flowers of benzoin in commerce, and by chemists is termed benzoic acid. It has all, or nearly all, the odor of the resin from which it is derived.
The extract, or tincture of benzoin, forms a good basis for a bouquet. [B] Like balsam of Tolu, it gives permanence and body to a perfume made with an essential oil in spirit. ”

“ The cooled reaction product is treated with 200 cc. of water, the layer of oil separated, washed once with a second portion of water, and subjected to distillation in vacuo. The first fraction of the distillate contains benzyl alcohol together with unchanged aldehyde, as well as a small quantity of water. The temperature then rises rapidly to the boiling-point of benzyl benzoate, when the receivers are changed. The product boils at 184-185'0/15 mm., and analysis by saponification shows it to consist of 99 per cent ester. A yield of 410-420 g. ”

“ The inferior sorts of benzoin are exported to Arabia, Persia, and some parts of India, where they are burned, to perfume, with their smoke, the temples and the houses of the inhabitants; to expel troublesome insects, and obviate the pernicious effects of unwholesome air or noxious exhalations.
Benzoin is brought for sale to the mercantile parts of Sumatra, in large cakes, covered with mats. In order to pack it in chests, it is necessary to break these cakes, and to expose it to the heat of the sun. ”

“ Similarly, the replacement of hydrogen by a water-residue, hydroxyl, gives rise to a phenol. The group of carbon, oxygen, and hydrogen atoms which confers the property of acidity upon an organic compound is a half-molecule of oxalic acid—it is known as the carboxyl group. Thus benzoic acid is the carboxyl-derivative of benzene, and the phthalic acid with which we are now concerned is a dicarboxyl-derivative of benzene. It is related to benzoic acid in the same way that diamidobenzene is related to aniline. ”

“ The trees continue to yield at the rate of about three pounds per annum for 10 or 12 years, after which period they are cut down. The resin which exudes during the first three years is said to be fuller of white tears, and therefore of finer quality, than that which issues subsequently, and is termed by the Malays Head Benzoin. That which flows during the next 7 or 8 years, is browner in colour and less valuable, and is known as Belly Benzoin; while a third sort, called Foot, is obtained by splitting the tree and scraping the wood; this last is mixed with much bark and refuse. ”

“ The worst quality is sold as “benzoin sorts,” consisting of brownish pieces without white spots; they are often mixed with splinters of wood, bast fibres, and fragments of leaves, and can be used only for cheap perfumes.
Good benzoin, besides the qualities named, must have a sweetish and burning sharp taste, it should be very friable, and when heated in a porcelain capsule should emit vapors (benzoic acid) of an acrid taste and a pronounced aromatic odor; it should dissolve completely in strong alcohol. ”

“ The first of the above-named substances, benzol, was discovered by Faraday, in 1825, in liquid produced by strongly compressing gas obtained from oil. He called it bicarburet of hydrogen; but afterwards another chemist, having procured the same body by distilling benzoic acid with lime, termed it benzine. It readily dissolves fats and oils; and is used domestically for removing grease-spots, cleaning gloves, &c., and in the arts as a solvent of india-rubber and gutta-percha. It is a very limpid, colourless liquid, very volatile, and, when pure, is of a peculiar but not disagreeable odour. ”

“ Benzoic acid and vanillin are the most important constituents. It is adulterated with Palembang benzoin, colophony, dammer, storax, and turpentine. Respecting the chemical investigation of commercial benzoin the above-mentioned work of K. Dieterich may also be referred to.
Benzoin is almost exclusively used for the preparation of chocolate varnish and sweets laquer, which are prepared by dissolving from 25 to 45 grammes of the laquer body in 100 grammes of strong spirit. The laquer body may contain varying quantities of benzoin and bleached shellac. ”

“ The washed oil then is subjected to a preliminary fractionation by distillation over a naked flame in the “crude benzol still.”
The several mixed benzols obtained are subjected finally to a further fractionation in stills worked with steam, to be divided into mixed products known by specific names in commerce. But these we cannot possibly consider here. We will rather give an idea of the way in which the several chemical species (benzene, toluene, &c.) are being isolated in a state of approximate purity to meet the demands of the tar-colour industry. ”

“ NIOSH Manual of Analytical Methods (NMAM) , Fourth Edition, 8/15/93 BENZIDINE in urine: METHOD 8304, Issue 2, dated 15 August 1993 - Page 2 of 4 REAGENTS:
EQUIPMENT:
1. Methyl alcohol. 2. Benzidine, 99% (CAUTION: CARCINOGEN) . * 3. Benzidine stock solution, 500 μg/mL. Weighed 50 mg benzidine. Dissolve in methyl alcohol to make 100 mL solution. Stable one month at -8°C. 4. Calibration stock solution, 10 μg/mL. * Dilute 1.00 mL benzidine stock solution to 50 mL with methyl alcohol. Prepare fresh daily. 5. Chloroform. 6. Hydrochloric acid. a. 1.0 N. Dilute 83 mL conc. ”

“ A too vigorous reaction is modified by cooling in cold water, and a too sluggish action quickened by gentle [Pg 72] heating (dipping in warm water) . If the mixture has a yellow color, dilute it with water, shake with ether, mix the decanted ethereal solution with alcohol and hydrochloric acid, add some zinc and place the whole in a lukewarm place to convert the nitrobenzol formed into aniline. After evolution of hydrogen is done, neutralize with potash lye, shake, take off the layer of ether, let the latter evaporate and add to the residue a few drops of calcium chloride solution. ”

“ Immerse a sheet of paper in a solution of India rubber, 4:100 of benzole, and let dry, which requires a few minutes. This is the flexible support. Then after exposure, brush over the India rubber solution on the carbon tissue, apply upon it the support when the benzole is evapor­ated, and pass the whole under a rolling press to secure adhe­sion, then develop. To transfer, soak the proof in tepid water, apply it on the material prepared, as it will be explained fur­ther on, and when dry, imbue the support from the back with benzole, to soften the India rubber, and strip. ”

“ Benzoic acid is perfectly soluble in hot grease. Half an ounce of benzoic acid being dissolved in half a pint of hot olive or almond oil, deposits on cooling beautiful acicular crystals, similar to the crystals that effloresce from vanilla beans; a portion of the acid, however, remains dissolved in the oil at the ordinary temperature, and imparts to it the peculiar aroma of benzoin ”

“ Benzol is a dreadful substance for spreading fire should it become ignited, for, being lighter than water, it floats upon its surface, and therefore the flames cannot be extinguished in the ordinary way. The discovery of the presence of benzol in coal-tar was made by Hofman in 1845. It is obtained from the light oil of coal-tar by first purifying this liquid by alternately distilling it with steam and treating with sulphuric acid several times. ”

“ Also from phthalic acid, C8H6O4, there may be obtained benzoic acid, C7H6O2, and carbonic anhydride, CO2, and as all the elements of phthalic acid enter into the composition of these substances, it follows that, although [311] they cannot re-form it by their direct action on each other (the reaction is not reversible) , still they form the direct products of its decomposition, and they occupy equal volumes. But benzoic acid, C7H6O2, is itself composed of benzene, C6H6, and carbonic anhydride, CO2, which also occupy equal volumes. ”

“ With old specimens, benzoline applied very lightly is most useful, but occasionally the mischief has extended to the wings, and the scales float off, leaving a black mass. In the case of heads, a solution of corrosive sublimate of such a strength as not to leave a white deposit on dark hair should be liberally applied, and when dry the hair should be brushed and combed, and wiped over with benzoline. Even when there are no Dermestes, it is a capital plan to saturate all heads once or twice a year with benzoline. ”