Ethyl, Nitrite

C 2 H 5 NO 2 . Syn. Nitric ether , Hyponitrous ether , Nitrite of ether , Nitrite of oxide of ethyl , Hyponitrite of E. ; Æther nitros us , Æ. hypo nitros us , L. This is a compound, of which ‘sweet spirit of nitre’ is an impure alcoholic solution. Prep. 1. Starch (potato farina), 1 part; nitric acid (sp. gr. 1·30), 10 parts; mix in a capacious retort, connected with a wide tube, 2 or 3 feet long, bent at right angles, and terminating near the bottom of a two-necked bottle, containing a mixture of alcohol (of 85%), 2 parts, and water, 1 part, and surrounded with a freezing mixture, pounded ice, or very cold water; the other neck of the bottle being connected by a long gla tube with a good refrigerator or condenser. All elevation of temperature must be avoided. The heat of a water bath only must be cautiously applied to the retort. The gas liberated pa es into the alcohol, causing the ether to distil in a gentle stream. The tube connecting the retort and bottle must be cooled by means of rag or moist paper, kept wetted with ice-cold water; as, if the temperature of the tube and the alcohol rises only a little, the latter becomes spontaneously hot, and boils violently, by which the product is vitiated. This proce is very productive and economical, and yields pure nitrous ether. 2. A mixture of oil of vitriol, 8 parts, and alcohol, 9 parts, is poured upon crystallised nitrate of ammonia, 11 parts, contained in any suitable distillatory ve el connected with a well-cooled receiver. Nitrous ether gradually distils over on the application of a gentle heat. An admirable proce , but more expensive than the preceding. Even a common fire may be employed without danger, as the liberation of the ether proceeds gradually, and not almost instantaneously, as in operating in the usual way. Sulphate of ammonia is left in the retort. The product is scarcely inferior to that of the last formula. 3. Rectified spirit, 46 fl. oz.; pure nitric acid (sp. gr. 1·500), 7 fl. oz.; put 15 fl. oz. of the spirit, with a little clean sand, into a quart matra , fitted with a cork, and a safety tube reaching to within an inch of the spirit, and a second tube leading to a refrigeratory. Fill the safety tube with pure nitric acid, then add through it, gradually and cautiously, 3 1 ⁄ 2 fl. oz. of the acid. When the violent action that ensues is nearly over, gradually add the remaining portion of the acid, 1 ⁄ 2 fl. oz. at a time, and at intervals. Agitate the ether that distils over, first with a little milk of lime, till it ceases to redden litmus paper, and then with half its volume of concentrated solution of chloride of calcium. The pure hyponitrous ether thus obtained should have a density of ·899. 4. (Mr John Williams.) Nitrite of ethyl is best made by pa ing nitrous acid gas into alcohol. The nitrous acid gas is prepared by acting upon such bodies as starch, copper, mercury, or arsenious acid with nitric acid. The alcohol is generally recommended in the text-books to be diluted with half its bulk of water; this, however, I consider a decided mistake. The alcohol should be as concentrated as po ible, even absolute alcohol is preferable. The main points to be attended to are that the current of nitrous acid gas should be slow and steady, so as to give time for the reaction to proceed properly, and that the ve el containing the alcohol should be kept as cool as po ible; in this way much of the production of bye-products will be avoided, and the gas can be pa ed through the alcohol, as long as it continues to be absorbed. The resulting liquid is anything but pure; it contains much nitrite of ethyl, some aldehyde, acid—it is even stated to contain malic acid. In fact it is well known that the reaction between the nitrous acid, and such products as alcohol, however pure, is not sharp, but is always accompanied by secondary products. From the crude alcoholic solution obtained by the method I have described, the pure nitrite of ethyl can be obtained without difficulty. Nitrite of ethyl is an extremely volatile liquid; it boils at about 61° F., whereas aldehyde boils at 90° F., and alcohol at 180° F. Taking advantage of this fact, we are enabled to separate it from the crude liquid by distillation. Some precautions are, however, nece ary, to ensure the purity of the product. The flask containing the crude product is placed in a water bath, and connected by bent tubes with several other flasks and bottles. The first tube should be pa ed into a small empty flask, this will condense most of the alcohol which may pa over during the operation. Then a second bent tube pa es into a second flask containing a little water; this condenses any alcohol which may not have been stopped in the first flask, together with free acid, and nearly all the aldehyde. From this wash bottle a third tube proceeds into a somewhat shallow flask, containing a strong solution of caustic potash; the gas, however, is not allowed to pa through this alkaline liquid, but simply over the surface. In this way the last portion of the aldehyde is absorbed, and the potash solution gradually a umes an amber colour. From this ve el, the gas (for such at the ordinary temperature of the laboratory, the nitrite of ethyl is—in very cold weather it would be nece ary to gently warm the different flasks) is pa ed through a tube charged with anhydrous chloride of calcium to absorb moisture, and the pure and dry nitrite of ethyl thus produced, finally pa es into alcohol, which readily absorbs it. It is only nece ary to note the weight of the alcohol used for absorbing the gas, and its weight at the end of the operation, to know the strength or per-centage of nitrite of ethyl which must be in solution. Thus, if 9 oz. of alcohol becomes 10 oz., it is evident we have a solution of 10 per cent.; if it becomes 12 oz., then the strength must be 25 per cent., and so on. Ordinary spirits will answer for condensing the nitrite of ethyl, but it is better to use absolute alcohol, as it is very desirable to avoid the presence of water in any form. The solutions made with weaker spirit soon turn acid; those made with absolute alcohol, on the other hand, keep a long time. It is very true the very strong solutions of 50 and 25 per cent. show traces of acidity when tested with moistened litmus paper, but the 10 per cent. solution is quite neutral. [283] [283] The object of Mr Williams’ paper, which is published in the ‘Pharmaceutical Journal’ for Dec. 8th, 1877, is to give instructions for the preparation of a pure nitrite of ethyl, which when mixed with alcohol in definite proportions, shall supersede the variable compound sold under the name of “Sweet Spirits of Nitre.” One point I have not mentioned; it is that the distillation must be conducted at the very lowest po ible temperature; in fact, the water in the water-bath should only be kept gently warm, and the proce should be continued only so long as the conducting tubes feel cool to the touch; when they become warm the distillation should be discontinued. By pa ing the gas into a tube in a freezing mixture, instead of into alcohol, the pure nitrite of ethyl is readily obtained in a liquid form; it is, however, nece ary to seal the tube, otherwise the very volatile liquid would soon be lost. Prop., . Pure nitrous ether has a pale-yellow colour, an agreeable odour of apples, and boils at 62° Fahr.; sp. gr. ·947 at 60° Fahr. Commercial nitrous ether contains aldehyde, boils at 70° Fahr., has a more or le suffocating odour combined with that of the pure ether, has a sp. gr. of ·886 at 40° Fahr., and turns brown when mixed with alcoholic solution of pota a, while the latter remains unaltered. It also acidifies by age, whilst pure nitrous ether remains neutral. They are both very inflammable, and burn with a white flame. Ordinary nitrous ether di olves in about 48 parts of water, and mixes in all proportions with alcohol and sulphuric ether. Nitrous ether is refrigerant, diaphoretic, and diuretic, but is seldom employed alone, though, when largely diluted with alcohol (sweet spirits of nitric, spirit of nitric ether), it is a common remedy in several diseases. It is also used to flavour malt spirit, in imitation of brandy (British brandy), although for this purpose it is vastly inferior to acetic ether. See Spirits (Medicinal).