22 IV.-On the Action of Bromine on Acetic Acid. BY VC'. H. PERKIN, F.C.S. AND B. F. DUPPA ESQ. SINCEthe publication of the notice which appeared in the "Philosophical Magazine" last September we have studied some of the reactions of bromacetic acid on various substances and have also succeeded in obtaining bibromacetic acid. We shall first describe the method pursued in making these interesting substances. Bronzacetic Acid. The best method of preparing this substance is to take a mix- ture of crystallizable acetic acid and bromine in the proportion of one equivalent of bromine to one of acid the object of the excess of acetic acid being to absorb the hydrobromic acid gas so as to relieve the tube of pressure and introduce it into a strong sealed tube which is then placed in an oil bath and heated up to 150"C.As soon as this temperature has been reached the bath may be allowed to cool down gradually; the cooling may occupy two hours or more. The mixture is then generally nearly colourless or of a light amber-brown. The decolorization takes place very suddenly at ahout 146"C. at which moment the tubes are apt to burst though the bath may have been as high as 155OC. The tube when quite cold is opened from which torrents of hydrobromic acid gas issue ; the contents are then transferred to a retort and a receiver being attached together with proper apparatus for the condensation of the hpdrobromic acid liberated heat is applied and the tempera- ture raised until it reaches 200" C.* The retort is then left to cool when after a time the whole of the liquid contents become solid and beautifully crystalline.This is a mixture of hy drobromic bromacetic and bibromacetic acids. These mixed acids are then heated to 130' C. and carbonic acid passed until the reaction of hydrobromic acid with nitrate of silver is no longer evident. Carbonate of lead in excess is then added together with about ten times as much water in bulk as there is acid ;the whole heated to 100' C. and allowed to stand for some hours; the liquid filtered off from the crystalline deposit which has formed; the As a quantity of bromacetic acid is carried over loiig before 200' C. is reached it is as well to re-distil the distillate. As an additional quantity of solid acid is thus procured the liquid may again be used with bromine for the productiou of more acid.ON THE ACTION OF BROMINE ON ACETIC ACID. crystals washed with a little cold water and diffused in water ;and sulphuretted hydrogen passed to saturation. The liquid filtered off and concentrated yields the crystalline acid in a state of purity. The object of the last process is to separate the bromacetic acid from the bibromacetic acid the lead salt of the latter being much more soluble than that of the former. The acid thus obtained crystallizes in rhombohedra; it is exceed- ingly deliquescent and very soluble in water or alcohol. It fuses below 100"C. and boils at 208' C. When distilled with acetate of potassium it gives off acetic acid; when heated witli metallic zinc it yields acetate and bromide of zinc.It undergoes a singular change when exposed to a high tempera- ture in a sealed tube carbonic oxide bibromacetic acid and appa- rently a little hydride of methyl being formed; it is possible that the following reaction may take place Bromacetic acid. Bibromacetic acid. It attacks the epidermis powerfully raising a blister like that produced by a burn; the effect when the acid is diluted takes place after eight or ten hours. Bromacetic acid forms crystallizable salts with most of the bases many of which decompose rapidly; few of these have been examined quantitatively . Bromacetate of Ammonium is a nearly uncrystallizable salt very soluble in water ;when heated it decomposes yielding bromide of ammonium.Bromacetate of Potassium. This salt is obtained by neutralizing a solution of carbonate or hydrate of potassium with bromacetic acid and evaporating the solution in a water bath. It is a crys- talline salt very soluble in water and alcohol. Bromacetate of Sodium is a very soluble salt insolublc or nearly so in alcohol. Bromacetate of Barium crystallizes with difficulty in small stars and contains water of crystallization; it is tolerably soluble in alcohol. Bromacetate of Calcium is a very difficultly crystallizable salt and very soluble in water. Bromacetate of Copper is a green crystalline salt very soluble in PERKIN AND DUPPA ON THE water. A solution of it appears to decompose when boiled as the colour becomes paler.The solution after stailding for some days deposits needle-shaped crystals and small malachite-green tufts of great beauty. They appear to contain a large quantity of water of crystallization. Bromacetate of Lead.-This salt is obtained either by neutra- lizing bromacetic acid with oxide of lead and recrystallizing the product in water or by adding a solution of bromacetic acid to a solution of acetate of lead washing the resulting crystalline pre- cipitate with cold water and then recrystallizing from water. A specimen dried at 100' C. when burnt with chromate of lead gave the following numbers ,9880 of Brornacetate of Lead gave *3717of Carbonic Acid and 00830of Water. A determination of lead and bromine gave the following numbers -674 of Bromacetate of Lead gave ,3106of Oxide of Lead and b5244of Bromide of Silver.These numbers lead to the following percentage composition Carbon .. .. .. 10.25 Hydrogen. . .. .. 0-92 Bromine .. .. .. 33-10 Lead .. .. .. 42.774 The formula requires the following numbers Theory. Exp. / h \ 4 equiv. of Carbon = 24.00 9.930 20.25 2 equiv. of Hydrogen= 2-00 0-820 '92 1 equiv. of Bromine = 79.97' 33.117 33.10 1 equiv. of Lead =103-57 42-878 42.774 4 equiv. of Oxygen = 32-00 13-255 1__1 241.54 100.000 ACTION OF BROMINE ON ACETIC' ACID. Bromacetate of lead crystallizes in needles is difficultly soluble in cold but moderately so in hot water. Bromacetate of Silver is obtained by treating bromacetic acid with carbonate of silver or by adding a solution of brornacetic acid to a solution of nitrate of silver.In the latter case it is thrown down as a beautiful crystalline precipitate which is washed with cold water and dried over sulphuric acid in vacuo. A determina-tion of the silver gave the subjoined number ; 06500of Bromacetate of Silver gave -4935of Bromide of Silver or 43.617 per cent. of Silver. The formula requires 48.9 per cent. of silver. This salt is very unstable decoimposing by ebullition bromide of silver and an acid which we shall refer to hereafter being formed. The dry salt if heated to about 90°C. decomposes with a sort of an explosion. It is rapidly acted upon by light when moist. Bromacetate of Methyl.-This substance is obtained by heating a mixture of hydrate of methyl and bromacetic acid in a sealed tube for an hour to a temperature of looo C.washing the product with water drying over chloride of calcium and rectifying. Bromacetate of methyl is a clear colourless mobile liquid having an aromatic odour highly irritating both to the nose and the eyes. It is heavier than water; it boils at about 144O C. decomposing gradually every time it is distilled. Ammonia acts on it very readily. Bromacetate of Ethyl is obtained in the same way as the pre- ceding substituting hydrate of ethyl for that of methyl. It is a clear colourless liquid heavier than water and highly irritating to the eyes and nose. It boils at 159' C. A combustion with chromate of lead yielded the following numbers 0.3821of substance gave 0.3922 of Carbonic Acid and 0.1215 of Water.PGREIN AND DUPPA ON THE A determination of bromine gave the following numbers 0.4942 substance gave 0.5110 of Bromide of Silver. These numbers give the following percentage composition Carbon .. .. .. 27.976 Hydrogen.. .. .. 3.533 Bromine .. .. .. 47.53 The formula C,H,BrO requires the following numbers Theory. Exp. -8 equiv. of Carbon 48.00 28.70 27'976 7 equiv. of Hydrogen 7.00 4.18 3-533 I equiv. of Bromine 79-97 47.70 47.530 4 equiv. of Oxygen 32.00 19-42 166.97 100*00 This substance decomposes partially every time it is distilled with evolution of hydrobromic acid. It is rapidly acted on by ammonia.Brornacetate of Amyl is obtained by heating hydrate of amyl with an excess of bromacetic acid washing the product with water and drying over chloride of calcium. It is an oily liquid having a pleasant odour when cold but if heated acts upon the eyes and nose like the preceding. It boils at 207°C. and decomposes partially every time it is distilled. Ammonia acts but slowly upon this substance in the cold. Two combustions of this substance gave the following results I. grm. -5091 of Bromacetate of Amy1 gave *7658of Carbonic Acid and 02916of Water. 11. -4829of Bromacetate of Amy1 gave -7071 of Carbonic Acid and *2675 of Water. ACTION OF BROMXNE ON ACETIC ACID. Percentage composition. I. Ii. Carbon .. . . 410.08 39.97 Hydrogen . . . . 6.41 6-15 which agrees with the formula as may be seen by the following comparison of the theoretical and experimental numbers 14 equiv. of Carbon 84.00 40.19 40.02 13 , Hydrogen 13-00 6.22 6.28 1 , Bromine 79-97 38.22 -4 , Oxygen 32.00 15-37 -208.97 100*00 A curious relationship exists between the boiling points of the acetates and the bromacetates of methyl ethyl and amyl. Although constant boiling points have not been obtained with the bromacetic ethers yet if the highest point at which the largest proportion comes over be taken it will be found that the bro-macetates boil at a temperature from about 82' to 86" C. higher than the corresponding acetates. Thus-Boiling Boiling point point. Di5.Bromacetate of Methyl 144" Acetate of Methyl 58" 86" 9 Ethyl 159" , Ethyl 74" 85" 1 Amyl 207" , Amyl 125" 82" A similar difference also exists between the boiling points of bromacetic and acetic acids. Boiling point of Bromacetic Acid = 208" ,> , Acetic Acid = 120" -88 diff. Could these substances be distilled without decomposition and a constant boiling point obtained it is very probable that the numbers would agree much more closely. PERKIN AND DUPPA ON THE Bibromacetic Acid. This acid is formed when a mixture of bromine and acetic acid is heated in presence of light; also in small quantities when bromacetic acid is heated. It is difficultto obtain in large quan- tities. We are at present endeavouring to find a process by means of which it may be produced with certainty in any quantity.Bibromacetic acid is a liquid boiling at about 240"C. ; it is decomposed partially every time it is distilled evolving hydro- bromic acid. It does not solidify at 15"C. It is possible that by the continued action of heat it might be transformed into tribro- macetic acid. Its specific gravity is very great. Bromacetic acid forms salts with most bases; they are in general uncrystallizable. Bibromacetate of Burium is deliquescent drying up to a gum- like sticky mass. Bibromacetate of Lead is uncrystallizable drying up to a highly refractive transparent substance attracting moisture and becoming opaque. It is very soluble in water. Bibromacetate of SiZwer is obtained by adding nitrate of silver to a solution of bibromacetic acid when it falls down as acrystalline precipitate.It is decomposed by ebullition with water into bro-mide of silver and a soluble acid. Two silver and one bromine determinations gave the following numbers I. *922of Bibromacetate of Silver gave 04196of Chloride of Silver. 114 06446of Bibromacetate of Silver wheu heated with carbonate of soda &c. gave $2154 of Metallic Silver '7160 of Bromide of Silver. Percentage composition. I. IT' Silver . . . . 33.0 33.41 Bromine . . .. -49-26 These numbers agree with the formula ACTION OF BROMINE ON ACETIC ACID. as may be seen by the following table : -Theory. Exp. 7 4 equiv. Carbon 24.00 7.364 7 2 , Hydrogen 2.00 0,613 1 , Silver 107.97 33.128 33.2 2 , Bromine 159.94 49.074 49-26 4 >t oxygen 32-00 9.821 -325-91 100.000 Bibromacetate of Ethyl is obtained by heating hydrate of ethyl with bibromacetic acid in a sealed tube at a temperature of 100"C.washing the product with water and drying over chloride of calcium. It is a colourless liquid heavier than water. It acts on the eyes and nose like the bromacetate of ethyl. It is possible that if a salt of bibromacetic acid were treated with sodium or metallic zinc an acid might be obtained standing to acetic acid in the same relation as acrylic acid stands to pro-pionic acid. M,C,(HBr,)O + 2Na = M C4H0 -t 2NaBr. We have lately studied the action of ammonia on brornacetic acid and have obtained some exceedingly interesting results.We find that when bromacetic acid is heated with ammonia there is formed a large quastity of bromide of ammonium and a beautiful white sweet tasting substance which we think without hesitation we may say is Glycocol. We have made a combustion of this substance gave the following numbers *3256of Substance gave *3837of Carbonic Acid and *1920of Water. Percentage composition. Carbon . . .. . . 3.21 Hydrogen . . .. *. 6-53 ON THE ACTION OF BROMXNE ON ACETIC ACID. The formula C,H5N0 requiring Carbon . .. .. 32.0 Hydrogen .. .. .* 6.6 There cannot therefore be any doubt as to the composition of this product being identical to that of Glycocol ; nevertheless we hope soon to give some confirmatory numbers.We also find that on boiling the bromacetate of silver in water we obtain a powerful syrupy acid and which has all the properties of glycollic acid. The formation of glycol and glycollic acid from bromacetic acid may eaaily be understood by the following equations C,(H,Br)O + 2NH = C4H,N0 + NH4Br GlyColl. Ag C4(H3Br)O4 + H,O = C4H406 + AgBr -Glycollic acid. We hope when we have completed our investigations on the formation of glycol and glycollic acid to give an account of the action of ammonia and of hydrate of silver on bromacetic acid and also of the action of zinc-methyl and zinc-ethyl on these new bromo-acids.