1270 BURKARD AND TRAVERS: THE ACTION OF CXXVII1.-The Action of Acetylene on the Acetates of Mercury . By EMIL BURKARD, Ph.D., and MORRIS W. TRAVERS, D.Sc. IN the year 1892, the late Dr. R. T. Plimpton published a short account of some compounds which he had obtained by the action of acetylene on mercurous and mercuric acetates in presence of water (Proc., 8, 109). By treating mercurous acetate suspended in water with acetylene, he obt.ained a sitbstance which resembled in its properties the well known acetylides of copper and silver, and the then unknown mercuric acetylide (Plimpton and Travers, Trans., 1894, 64, 264). When treated with hydrochloric acid, it yielded acetylene, it detonated when heated, and with a soIution of iodine, tetriodoethylene and di-iodoacetylene were formed.The compound was not analysed, and the paper contains no suggestion with regard to its formula. When acetylene was passed through a solution of mercuric acetate, P1irr;pton found that a substance of totally different character was formed. The compound to which he assigned the formula 3Rg0,2C2H, did not explode when heated, and when treated with acids it yielded the corresponding mercuric salt and aldehyde. We have taken up the subject a t the point at which i t was left in the year 1892. Action of Acetylene on Mercurous Acetate. Since mercurous acetate is insoluble in water, it is necessary to suspend the finely divided crystals in water and to shake the mixture freely while treating it with acetylene. The reaction takes place rapidly at first, but a s the acetate becomes coated with a layer of the acetplide, the change proceeds more slowly and requires about 30 hours for completion.The reaction must be carried out in absence of daylight, which decomposes the mercurous acetate. The product is always grey in colour, even when the acetylene is perfectly free from sulphuretted hydrogen or phosphoretted hydrogen. The colour is probably due to the presence of a trace of free mercury in insufficient quantity to be of any importance. When the reaction is at an end, the mercury is completely precipi- tated, and by titrating the solution with alkali it is found to contain the whole of the acid originally present in the mercurous salt. The solution has always a strong odour of aldehyde produced by the hydrolysis of the acetylene ; this reaction will be discussed later.TheACETYLENE ON THE ACETATES OF MERCURY. 1271 precipitate, after washing with water and alcohol and drying over sulphuric acid in a desiccator, appears to have a definite composition. The following are the results of analyses : (i) 0,3845 gave 0.4050 HgS. Hg=90*79. (ii) 0.2575 ,, 0.2705 HgS. H g = 90.55. (iii) 0.4287 ,, 014510 HgS. Hg = 90.66. (i) 0.2855 ,, 0.0570 CO, and 0.0150 H,O. C = 5.44; H,O= 5.25. (ii) 0.3405 ,, 0.0715 CO, ,, 0.0180 H,O. C = 5.72; H,O = 5.20. The substance was mixed with n *large quantity of powdered copper oxide before it was introduced into the combustion tube, and a long spiral of silver foil was placed in the tube a t the end nearest t o the absorption apparatus. The silver absorbed the greater part of the mercury vapour, but traces always passed into the sulphuric acid tube, rendering the water determination of no value.If the determinations of the mercury and the carbon are correct, the quantity of water present, determined by difference, is 3.76 per cent. The percentage composition indicates t h a t the compound has the formula C,Hg,,H,O : The combustion was extremely difficult to carry out. O,Hg,. 2C,Hg2, H20. C,Hg2, H20. C,Hg2, 2H20. Hg ............ 94.33 92.50 90.50 86-95 H,O.. .......... - 2.07 4-07 7.83 C ............... 5-66 5.58 5.43 5.22 The substance is then, as Plimpton suggested, closely allied to the acetylides of silver and copper, and t o the mercuric acetylide discovered in 1894. It differs from these compounds in containing one mol.of water to one mol. of the acetylide, whereas the acetylides already known have the general formula SC,M”,H,O. That the water in our compound is present either in combination with the mercury or as water of crystallisation is indicat,ed by the fact that it yields mercurous iodide and tetriodoethylene when treated with a solution of iodine, and acetylene when treated with hydrochloric acid, The water cannot, however, be removed by heating, for at 100’ the compound decomposes, losing, not only water, but carbon, and leaving a residue of indefinite composition. Action of Acetylene on a Xolution of Mercuric Acetate. When acetylene is passed into a solution of mercuric acetate in absence of daylight, a white precipitate is immediately thrown down.The precipitate becomes grey in colour as the reaction proceeds, and the solution smells strongly of aldehyde, produced by the hydrolysis1272 MELLOR AND RUSSELL: THE PREPARATION OF PURE of some of the acetylene in solution. After about two hours, the whole of the mercury is precipitated, the acetic acid remaining in the solu- tion. The precipitate is found to have a somewhat slimy character and is difficult to wash on the filter-paper. This compound, after drying for some days in a vacuum over sul- phuric acid, was analysed, with the following results : 0.4155 gave 0.0940 COP C = 6.16. 0.3100 ,, 0*0676 CO,. C = 5-98. 0.2660 ,, 0.2'703 HgS. Hg = 87.62. 3C2Hg,2Hg0,2H20 requires C = 6.3 ; Hg=87.7 per cent. The compound is not explosive, but on heating strongly it decom- poses, leaving a residue of carbon ; at looo, it loses both water and carbon, leaving a residue of indefinite composition.With a solution of iodine, it yields only mercuric iodide and tetriodoethylene with a little di-iodoacetylene, hence it, is probable that in this compound, as in the case of the compound derived from mercurous acetate, the water is not directly combined with the carbon. The compound may, in fact, be regarded as a basic acetylide of the formula 3C2Hg,2Hg(OH),. That the compound yields aldehyde and little or no acetylene when heated with acids may be due to the fact that acetylene hydrolyses with great readiness t o aldehyde in the presence of mercuric salts. I n the case of mercuric acetylide, C,Hg (Zoc. cit.), and hydrochloric acid, a considerable quantity of aldehyde is formed, and as in the com- pound we have just described, mercury is present in greater propor- tion. More aldehyde is formed by the action of acids. The hydrolysis of acetylene to aldehyde hag never been carefully studied. The sub- ject is well worth investigation, particularly with the view of determining whether vinyl alcohol is formed as a half-way product. UNIVERSITY COLLEGE, LONDON.