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NITROGLYCERIN, C3H
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See also:NITROGLYCERIN, C3H ,(NO3)3 or CH2NO3 • CHNO3 • CH2NO3 glyceryl trinitrate, an explosive first obtained in 1846 by Ascanio Sobrero (Mem. Acad. Torino, 1847) by acting with a mixture of strong nitric and sulphuric acids on See also:glycerin at the See also:ordinary temperature. The reaction proceeds in several stages, mono-, di- and finally tri-nitrate being produced, the final See also:stage requiring sulphuric See also:acid as a dehydrator. When pure it is a very See also:pale yellow oil of sp. gr. 1.614 at 4° C. and 1.6o at 15° C. One See also:gram requires for See also:solution between 800 and See also:I000 c.c. of See also:water, 4 C.C. of See also:absolute See also:alcohol or 18 c.c. of See also:wood spirit, and it is scarcely at all soluble in glycerin itself, but mixes in all proportions with See also:ether, See also:acetone, See also:ethyl acetate and See also:benzene. In the manufacture glycerin is dropped in a very thin stream into a mixture of 3 parts of nitric (sp. gr. 1.5) and 5 parts of sulphuric acid (sp. gr. 1.84), the containing See also:vessel being cooled by a water jacket and the acid mixture agitated by a stream of cooled See also:air, the temperature being kept at about 15° C. A considerable excess of acids is necessary for the completion and safety of the reaction, usually about 8 parts of the acid mixture to i of glycerin. The higher the strength of the acids the higher the yield of nitroglycerin and the smaller the loss by solution in the See also:waste acids. In See also:recent practice some sulphin trioxide, or fuming sulphuric acid, is added, so that the mixture of acids contains less than i % of water. The See also:action is very rapid, and the product, which rises to the See also:top of the acids, is separated and washed successively with See also:cold and then tepid water, and finally with water made slightly alkaline with See also:sodium carbonate or hydroxide, to remove all adhering or dissolved acids which would otherwise render the product very unstable. Nitroglycerin dissolves a little water and then aooears thick or milky. Generally it is either dried, after being separated from the See also:wash water, by means of See also:common See also:salt, upon a layer of which the moist nitroglycerin is gently run and allowed to drain or See also:filter through, or it is filtered through a See also:mass of dry sponge or similar dry and porous material. Under ordinary pressure it boils at above Zoo° C. (L. de Bruyn). If gradually heated it begins to vaporize and decompose at about 130°, and as a See also:rule it detonates when heated slightly above this temperature, previously giving off some red fumes. A little vapour is given off at ordinary temperatures and pressures, and when under a few millimetres pressure only it rapidly vaporizes below zoo° C. The freezing-point is uncertain, owing perhaps to the existence of two modifications, as suggested by Kast (Zeits. f. ges. Schiess- u. Sprengstoff, 1-225; see also S. Nauckhoff, Zeits. f. ang. Chem., i8, Heft i and 2). It is frequently given as 43° to 46° F. (about 6° to 8° C.), and it is stated to be more sensitive to percussion when frozen (Beilstein). It crystallizes (in See also:long needles) more easily when gently agitated during the cooling, or when mixed with such substances as kieselguhr. At one See also:time it was transported all over See also:America in a frozen See also:condition without serious accidents, and according to See also:Sir F. Nathan (Jour. See also:Soc. Chem. Ind., 1908, 27, p. 5) it is safer to export in the frozen See also:state. To prevent the freezing of nitroglycerin in See also:dynamite it has been proposed to add various substances, such as chlordinitroglycerin, nitrated diglycerin or tetranitrodiglycerol, and also mono-and di-nitroglycerin. The latter two have been studied by C. W. Will (See also:Bee., 1908, 7, p. 407), who obtained two isomeric dinitroglycerins, one of which is eminently crystallizable and the other fluid. Both are sensitive to percussion, but a little less so than nitroglycerin. The mononitroglycerin also exists in two forms, neither of which is strictly speaking explosive. It appears that an addition of dinitroglycerin to nitroglycerin would materially retard its freezing or lessen its sensitiveness (see also C. Claessen, Ger. Pat. 210990 (1909)). Mono. Di. Tri. Specific gravity 1.40 1.47 1.6 Melting-point . a 58° a See also:hydrate, 26° labile, 2.2° R 54° $ hydrate (fluid) See also:stable, 12.2 ° Boiling-point 18 mm. 155-16o° 145° about 16o° Solubility 70 % 7.7 % -16% The liquid when soaked into a porous combustible substance like blotting-See also:paper See also:burns rapidly and quietly, and when struck with a See also:hammer on a hard See also:surface violently detonates; when a little of the liquid is spread on an See also:anvil and struck, the portion immediately under the hammer only will, as a rule, detonate, the See also:remainder bein scattered. Some solutions of nitroglycerin (in ether, acetone, &c. See also:burn quietly, and the same is the See also:case when it is held in solution or suspension in a colloid substance, as gelatinized See also:guncotton, &c. Strong sulphuric acid dissolves nitroglycerin, and this solution on being poured into water yields dinitroglycerin (see Will, loc. cit.) and also some mononitroglycerin. When the solution in the strong acid is allowed to stand, some nitric acid is first evolved, and as the temperature rises this is followed by a See also:general decomposition of the substance, though not necessarily an explosive one. Shaken with See also:mercury and sulphuric acid, nitroglycerin yields its See also:nitrogen as nitric See also:oxide; the measurement of the See also:volume of this See also:gas is a convenient mode of estimating nitroglycerin. See also:Ammon um hydroxide has no appreciable action at ordinary temperatures, but strong solutions of sodium or See also:potassium hydroxides start a decomposition, with rise of temperature, in which some nitrate and always some nit-rite is produced. Some glycerin may be re-formed, but with very strong alkaline solutions little of the glycerin See also:molecule escapes destruction, oxalic acid and several other products resulting. Alcoholic solutions of the alkalis also produce much nitrite along with some formate and acetate. See also:Calcium or potassium sulphides and potassium hydro-sulphides completely reduce nitroglycerin to glycerin, some of the See also:sulphur being oxidized and some precipitated. Hydriodic acid reduces it to glycerin and nitric oxide. See also:Aniline and similar bases are oxidized and partially nitrated by nitroglycerin, with the See also:production of non-explosive compounds. The first attempts to utilize the explosive See also:power of nitro-glycerin were made by See also:Nobel in 1863; they were only partially successful until the See also:plan, first applied by General Pictot in 1854, of developing the force of See also:gunpowder in the most rapid manner and to the maximum extent, through initiative detonation, was applied by Nobel to nitroglycerin. Even then, however, the liquid nature of the substance, though advantageous in one or two directions, constituted a serious obstacle to its safe transport and storage and to its efficient employment; it was therefore not until Nobel produced plastic solid preparations by mixing the liquid with porous substances, such as gunpowder, or See also:carbon and sulphur, and finally kieselguhr in a See also:fine state of See also:division, capable of absorbing and retaining considerable quantities of it, that it could be employed as a See also:blasting See also:agent (see See also:EXPLOSIVES, DYNAMITE, See also:CORDITE), (W. R. E. H.) See also:Therapeutics.—Nitroglycerin has a sweet burning See also:taste and is decidedly poisonous. Its vapour produces violent headache, and the same effect is often caused by handling compositions containing it. See also:Prior to its use as an explosive, its alcoholic solution found application in See also:medicine under the name of glonoin. Although a nitrate, its pharmacological actions resemble those of nitrites such as amyl nitrite, taken internally. The explanation is that in an alkaline See also:medium at See also:body See also:heat nitroglycerin yields a nitrite, probably as a preliminary stage of See also:resolution. Nitroglycerin shaken up with warm very dilute alkaline solutions, as sodium carbonate, for a few minutes only, always yields sufficient nitrite to give the diazoreaction; and, as stated, strong alkaline solutions always produce some nitrite as one of the decomposition products. This See also:gradual See also:conversion in the tissues is a valuable See also:property of nitroglycerin, as its effects take longer to See also:manifest themselves than is the case with amyl and other nitrites. Nitroglycerin is valuable as a preventive in cases of cardiac See also:pain, such as angina pectoris, and it is also used in other conditions where it is desirable to reduce the arterial tension. The See also:British See also:Pharmacopoeia contains a liquor trinitrini (1%), and tablets made up with See also:chocolate, each containing one-hundredth of a See also:grain. Additional information and CommentsThere are no comments yet for this article.
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