PERKIN ON PROPIONIC COUMARIN III.-Om Propionic Cowmaria and some of its Derivatives. By W. H. PERKIN, F.R.S. OURknowledge of the coumarins extends at present to the valeric derivative; but to render the series complete as far as it goes the propionic coumarin has been wanting ; and it appeared to me that it would be desirable to prepare this substance not only to complete the series but also to compare its properties with ordinary or acetic coumarin to which it is so closely related. I have therefore made some experiments upon the subject the particulars of which I now beg leave to lay before the Society. Propionic Anhydride. Thc propionic anhydride employed in these experiments was obtained AND SOME OF ITS DERIVATIVES. by distilling propionic chloride with dry sodium propionate.The pro- pionic acid used was prepared from ethylic cyanide. The anhydride is a colourless liquid having an odour somewhat like that of butyric anhydride but more irritating. It boils at 168"-169" and has a specific gravity of 1.0169 at 15" C. Specimens burnt with oxide of copper gave the following numbers :-I. a198 of substance gave ,4035 of COz and -140of water. 11. ,293 of substance gave r5965 of COaand ,204 of water. These give the following percentages :-I. 11. C6H1003requires. Carbon .......... 55.55 55.45 55.38 Hydrogen ........ 7.89 7-73 '7.69 Propionic Cozlmariw. Propionic anhydride acts much more slowly on hydride of sodium-salicyl than acetic anhydride. If heat however be applied chemical action sets in and a fluid product is soon obtained.In my experiments I have always used a considerable excess of pro- pionic anhydride and boiled it with the sodium compound for an hour or more the excess of anhydride and the resulting propionic acid being afterwards distilled off. The crude coumarin remaining in the retort is freed from sodium propionate by pouring it into boiling water in which it sinks as a heavy oil but solidifies into a browuish crystalline mass on cooling. It is then collected and distilled to render it colourless and after being well pressed between bibulous paper twice crystallised from alcohol. In this way it is obtained in beautiful transparent slightly oblique prisms. It gave on analysis the following numbers :-I.-273 of substance gave *760of C02 and a126 of HzO. 11. -2675 of substance gave ,738 of CO and -1265 of water. These numbers give perceiitages agreeing closely with those required by the formula- PERICIN ON PROPIONIC GO UlliIBRIN -Theory. Experiment. /-I. 11. C, .......... 120 75.0 74-90 75-21 H .......... 8 5.0 5.12 5.25 02 .......... 32 20.0 - -160 100.0 Propionic coumarin possesses an odour difficult to distinguish from that of ordinary cournarin. At 90' it melts and on cooling solidifies to a beautifully crystalline mass. It can be distilled without decom- position. Boiling water dissolves it to a small extent the solution becoming milky as it cools and afterwards depositing fine hair-like crystals.It is moderately soluble in cold and easily soluble in boiling alcohol. Propionic coumarin is nearly insoluble in cold aqueous potassium hydrate and when gently heated melts and floats as an oil on the sur- face of this alkaline solution. If boiled however it dissolves forming a clear pale yellow liquid which becomes opaque when concentrated. On standing an oily liquid rises to the surface and solidifies on cooling to a tenacious mass. It is easily soluble in water and is decomposed with separation of the propionic coumarin upon the addition of an acid. When fused with potassium hydrate this coumarin yields a crystal-line acid probably a propionic coumaric acid but when it is more strongly heated with potassium hydrate salicylic acid is produced.P-Bromopropionic Coumarin. If the hydride of sodium-salicyl med in the preparation of propionic coumarin be replaced by the hydride of sodium-bromosalicyl a brominated product is obtained homologous with P-bromocoumarin or in other words a bromopropionic coumarin is produced the bromine being in the Csgroup. This product when crystallised from alcohol is obtained in long thin needles. When propionic coumarin is mixed with bromine in excess it dis- solves and on driving off the excess of bromine and hydrobromic acid by heating the mixture over the water-bath and then over the lamp a crystalline product is obtained which generally weighs nearly half as much again as the coumarin employed showing that about one atom of hrdrogen has been replaced.On recrystallising the product from alcohol long thin needles are obtained which are also /%bromopro-pionic coumarin. Analyses of specimens prepared by both the above processes gave the following numbers :- AND SOME OF ITS DERIVATIVES. I. ,236 grrbm of substance prepared from hy dride of sodium-bro-rnosalicyl gave *434gram of CO and -063 gram of water. 11. -297 grm of substance prepared from propionic coumarin and bromine gave ,5455 gram of C02and *077gram of H,O. 111. -2385 gram of substance Same as No. I1 gave -4385 gram of CO and -065 gram of H20. These give percentages agreeing closely with those required by the formula-Theory. Experiment. . -I F I. 11. 111.\ Cia ...... 120 50.20 50-15 50.08 50.1 H7 ......7 2.92 2.96 2.88 3.03 Br ...... 80 33.47 --02 ...... 32 13.41 --a-bromopropionic coumarin vhen heated melts at 146O and on cool-ing solidifies to a crystalline mass. It can be distilled with but little decomposition. It dissolves easily in boiling alcohol but is less soluble than propionic coumarin. It gradually dissolves in a boiling solution of potassium hydrate and may be precipitated unchanged by acids. When fused with potassium hydrate it gives an orange-red coloured product potassium bromide being formed. 6-Dibromopropionic Coumarh. When propionic coumarin is heated for a few hours in a sealed tube to about 150" with twice its weight of bromine dissolved in carbon disulphide large quantities of hydrobrornic acid are formed and on evaporating the carbon disulphide and twice crystallising the residue from benzol a crystalline product is obtained which gave on analysis the following numbers :-I.-296 of substance gave ~417of GO2 and -056 of H,O. 11. *3085of substance gave -436 of COz and ~053of I120. PERKTN ON PROPIONIC COUMARIN ETC. The formnla CloH6Brz02, requires the following percentages :--Theory. Experiment. / I. 11. c, ...... 120 37.73 38-41 38-6 H ...... 6 1.90 2-11 2.19 Brz ...... 160 50.31 -0 ...... 32 10-06 -318 100-00 These results are not so close to the theory as could be desired ; the excess of carbon however is probably owing to the presence of the trace of monobromopropionic coumarin . I believe that the bromine in this substance is all in the C group as it does not seem to be touched with caustic alkali until it is fused with it when the mixture changes to an orange-red colour in the same manner as the 6-monohromo-derivative.I therefore have called it 6-dihomopropiofiic cournarin. Dibromide of Propionic Coumnh. Propionic coumarin when exposed to the action of bromine-vapour in the cold changes to a viscid liquid and greatly increases in weight. The product appears to be the dibromide corresponding with dibromide of coumarin but I have not been able to get it sufficiently pure for analysis. With caustic alkali Fropionic coumarin is separated from it. It will be remembered that the dibromide of coumarin under these circumsfances yields a-bromocoumarin which if further treated with alkalies gives coumarilic acid.Xzclpphopropionic CozcrnarilicAcid. Propionic coumarin dissolves in fuming sulphuric acid without any change of colour and on gently heating the mixture in the water-bath it is entirely convei+ed into a sulpho-acid. This is easily converted into the barium salt by treatment with barium carbonate and filtering from the barium sulphate. On concentrating the filtrate and allowing it to stand small but brilliant crystals are obtained which contain a considerable quantity of water of crystallisation ; part of this is given off by drying irz vacuo and the rest at 150" C. It gave the following numbers on analysis :-I. -0855 of substance dried at 150" C. gave -0325 of barium sulphate = 22.26 p.c. barium.11. -297 of substance air-drird lost -068 of water at 150 = 22.9 p,c. BECKETT AND WRIGHT ON THE ACTION ETC. The formula C20H1P04BaS20S, requires 22.77 p,c. barium and CmH,,04BaS,06.10 aq. requires 22.9 of water. From the foregoing results we see that although this coumarin corresponds in most of its properties to those of ordinary coumarin yet it differs in some particulars especially in its tendency to produce @-derivatives with bromine whereas with ordinary coumarin the ten- dency is in the opposite direction.