RESORCIN (

See also:

• META

meta-dioxybenzene),

See also:

• C5H4

C5H4(OH)2i one of the dihydric phenols. It is obtained on fusing many resins (

See also:

• GALBANUM (Heb. Helben¢h; Gr. xaXfiavrl)

galbanum, asafoetida, &c.)  with caustic potash, or by the distillation of Brazil-wood extract . It may be prepared synthetically by fusing meta-iodophenol, phenol meta-sulphonic acid, and benzene meta-disulphonic acid with potash; by the action of nitrous acid on meta-aminophenol; or by the action of 1o% hydrochloric acid on meta-phenylene diamine (J . Meyer, Ber., 1897, 30, p . 2569) . Many ortho and para-compounds of the aromatic series (for example, the brom-phenols, benzene para-disulphonic acid) also yield resorcin on fusion with caustic potash . It crystallizes from benzene in colourless needles which melt at 119° C. and boil at 276.5° C . (L . Calderon), or 280° C . (C . Graebe), and is readily soluble in water, alcohol and ether, but insoluble in chloroform and carbon bisulphide . It reduces Fehling's solution, and ammoniacal silver solutions . It does not form a precipitate with lead acetate solution, as the isomeric pyrocatechin does .

Ferric chloride

colours its aqueous solution a dark violet, and bromine water precipitates tribromresorcin . Sodium amalgam reduces it to dihydroresorcin, which when heated to 150-16o° C. with concentrated baryta solution gives y-acetylbutyric acid (D . Vorlander); when fused with caustic potash, resorcin yields phloroglucin, pyrocatechin and diresorcin . It condenses with acids or acid chlorides, in the presence of dehydrating agents, to oxyketones, e.g. with zinc chloride and glacial acetic acid at 145° C. it yields resacetophenone (HO)2C6H3•CO.CH3 (M . Nencki and N . Sieber, Jour. prak . Chem., 1881 [2], 23, p . 147) . With the anhydrides of dibasic acids it yields fluoresceins (q.v.) . When heated with calcium chloride-ammonia to 200° C. it yields meta-dioxydiphenylamine (A . Seyewitz, Bull . Soc .

Chins., 1890 [3], 3, p . 811) . With sodium nitrite it forms a water-soluble

blue dye, which is turned red by acids, and is used as an indicator, under the name of lacmoid (M . C . Traub and C . Hock, Ber., 1884, 17, p . 2615) . It condenses readily with aldehydes, yielding with formaldehyde, on the addition of_ a little hydrochloric acid, methylene diresorcin [(HO)2•C6H3]2•CH2, whilst with chloral hydrate, in the presence of potassium bisulphate, it yields the lactone of tetra-oxydiphenyl methane carboxylic acid (J . T . Hewitt and F . G . Pope, Jour .

Chem . Soc., 1897, 71, p . 1084) . In alcoholic solution it condenses with sodium acetoacetate to form 13-methylumbelliferone, C50H803 (A .

Michael, Jour. prak . Chem., 1888 [2], 37, 470) . With concentrated nitric acid, in the presence of cold concentrated sulphuric acid, it yields trinitro-resorcin (styphnic acid), which forms yellow crystals, exploding violently on rapid heating . In medicine, resorcin, which is official in the United States under the name of resorcinol, was formerly used as an anti-pyretic, but it has been given up . The dose is 2 to 8 grs . Used externally it is an antiseptic and disinfectant, and is used 5 to 10 % in ointments in the treatment of chronic skin diseases such as psoriasis and eczema of a sub-acute character . Weak, watery solutions of resorcin (10 or 15 grs. to the ounce) are useful in allaying the itching in erythematous eczema . A 2% solution used as a spray has been used with marked effect in hay fever and in whooping-cough .

In the latter disease to minims of the 2% solution has been given internally . It has also been employed in the treatment of gastric

ulcer in doses of 2 to 4 grs. in pill, and is said to be analgesic and haemostatic in its action . In large doses it is a poison causing giddiness, deafness, salivation, sweating and convulsions . It is also worked up in certain medicated soaps . Mono-acetyl resorcin, CBH4(OH)•O•COCH3, is used under the name of " euresol." Resazurin, C12H7NO4, obtained by the action of nitrous acid on resorcin (P . Weselsky and R . Benedikt, Monats., 188o, 1, p . 889), forms small dark red crystals 'possessing a greenish metallic glance . When dissolved in concentrated sulphuric acid and warmed to 21o° C., the solution on pouring into water yields a precipitate of resorufin, C12H,NO3, an oxyphenoxazone, which is Insoluble in water, but is readily soluble in hot concentrated hydrochloric acid, and in solutions of caustic alkalis . The .alkaline solutions are of a rose-red colour and show a cinnabar-red fluorescence . A tetrabromresorufin is used as a dye-stuff under the name of Fluorescent Resorcin Blue . Thioresorcin is obtained by the action of. zinc and hydrochloric acid on the chloride of benzene meta-disulphonic acid .

It melts at 27° C. and boils at 2430 C . Resorcin disulphonic Acid (HO)2C6H2(HSO0)2, is a deliquescent

mass obtained by the action of sulphuric acid on resorcin (H . Fischer, Monats., 1881, 2, p . 321) . It is easily soluble in water and decomposes when heated to too' C .