10
HEPTTLMALOSIC A S D HEPTYLACETIC ACIDS.
IEEPTPLMALOXIC' A K D IIEPTTLAC'ETIC ACIDS.
F. P.
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A h i e f mention of the preparation of these t M o acids has already been macle (Ber. SIII., 1657). I have since utilized the small anioiint of the acids wliic1i I had on hand ill the preparation of some new salts, ant1 will gi\ c' a dewription of them, as they s e r ~ eto characterize these acids mow fully than was done in the pre\ ioits notice. I ~ E I ' T T L J I A L O S I C A C I D C,,H,,O,. ,, 1liis acid belongs to the oxalic acid series and is an isomer of sebacic acid, I t canlprepared from heptylmalonic ether. The sitnplest decomposition of this ether by means of an alkali is of course the breaking up into alcohol and heptylmalonic acid. W e can look npon the reaction as taking place in accordance with the following forninla :
C,,I~,,O,(C,l-I,),+2HOI(=C,,H,,O,K,+LC,H~OH. An alcoholic solution of potassium hydroxide was used. A small portion of the ether and four times the theoretical anionnt of potassium hydroxide were heated four to six hours in a small flask upon tlie water bath. A t the close of tlie reaction water was added, and then hydrochloric acid, and tlie whole gently heated. The heptylmalonic acid separated as a brown-colored oil on tlie surface of the water This W'RS then sliaken with ether, allowed to stand for evaporation of the ether and the residue placed in a desiccator o\ er bulpliiiric acid The niasb solidified, but was still a yellow color, and after drying gave the melting point at 90-93" C. I n order to free the acid from all impuritieb it was washed well with petroleum ether It proked nlmoit insoluble in this liquid, and was left as a white crystalline niabs, melting by 97-98' c'. (uncorrectecl). I t is hut slightly soluble in water, but. easily so in alcohol, chlorofornl and ether. Tlie solution has n strongly acid reaction. Analyses mere made as follo\r5 :
I. 0.1432 grm. of acid taken IT. 0.1557 grm. of acid taketi Calcnlated for C,,H,,O,
$ C=i59.76 $ C=59.53 $ C'=59.41
d 11=9,01 $ H=3.04. $ H=S.!ll,
5 Oe31.98.
"lie acid is dibasic and capable of sitbstitiiting carbonic acid in tlie cold. Heated to 130-160" C it hreaks up into lieptglacetic
HEPTYLMALONIC AND HEPTYLACETIC ACIDS.
11
acid and carbon dioxide, The s d t s crystallize very indistinctly, if a t all, and are easily soluble only in the case of the alkalis. SILVER
HEPTYLMALOSATE.
An aqueous solution of ammonia was added to the acid until nearly neutralized, and the ammonium heptylmalonate formed in this way was added to a solution of silver nitrate, causing a white precipitate of silver heptylmalonate. The precipitate is heavy and white, seemingly composed of minute, indistinct crystals, and is quite insoluble in water, whether cold or hot. Alcohol also fails to dissolve it appreciably. I t was dried in a steam-bath to a constant weight. Only after long keeping does it change to 3 reddish brown. The melting point, as determined with a portion only slightly changed in color, was 244" C. Two determinations of silver were made. I. 0.4330 grm. silver salt taken, $ Ag-51.34. 11. 0.3304 grm. silver salt taken, $ Ag=51.56. Calculated for C,,H,,O,Ag,. $ Ag=51.92.
BARIUXHEPTTLJIALONATE. As in the case of the silver salt, this was obtained as a precipitate from barium chloride by means of ammonium heptylmalonate. It is a white amorphous powder, insoluble in water and alcohol. The salt was dried at 100" C. ahd analyzed. I t can be heated t o 160" C. without suffering decompositi n.
I. 0.3008 grm. barium salt taken, found $ Ba=40.19. 11. 0.5133 grm. taken, found $ Ba=40.45. Calculated for C,,H,,O,Ba.
$ Ba=40.65.
COPPERHEPTTLJIALOSATE. The ammonium salt was not used in the preparation of this compound, but the acid itself (slightly impure) dissolved in water and added to a concentrated solution of pure cupric sulphate. The impure acid was used because the traces of impurity made it much more soluble in water, and the nature of the impurity did not seem to interfere with the formation of the cupric salt. The addition of the acid caused a light-blue precipitate, which was washed well with water. As it was somewhat soluble in water, an excessive use of this had to be avoided. I t is more soluble in alcohol, and on evaporation is left behind as an indistinctly crystalline mass. On standing several days over sulphuric acid it becomes almost dry
12
IIEPTYLJIALOSIC A S D HEI’TYLACETIC ACIDS.
and loses at 100” C. the last traces of n-atcr. On further heating it suffers no loss in weight, iintil at quite a high tcniperature it begins to turn brown ant1 dCCOln~JOW. It w?nii therefore to) contain no water of cry~tallixation. Analysis : 0.3253 grin. taken, foritid < Cn=BY.SO. Calculated for C’,,Hi,O,Cu $ (‘u=24.04.
LEADHEPTYI \rAi.osAib: Alcoholic solutions of 1iel)tyliiialonic ‘wid and lead acetate were made, and on mixing then1 a hen\) F\ liitc precipitate formed. This precipitate mes repeatetlly mashed with water, and sonic of the last washings were evaporated, YitJIdiiig scarcely any i~eaidue,thns J i o w ing the almost entire insoluhiIity of the lead heptylnialonate ill that solvent. I n alcohol it is slightly solable. ,iftei. tliorough washing, the precipitate was dried i n the \teain-bath ; clrging at 110”C’. caused no further loss in weight. A portion of the dried calt \va5 taken for a determination (Jf the melting p o i l i t : melting at 235’ c’. The remainder of the precipitate, amoanting to pearly 0.2 grni* , W R S taken for analysiq. I t was di.so!veil i t i dilute nitric acid and tlie lead deterniinccl liy eva1)oration with ~iilphnricacitl. Analysis : found, < Pb=50.49. (‘alculated for (’luII,60,Pb, ci Ph=50.89 ZISU
HEP1’YLvAI.oSATE
On adding an iilcoholic solution of the acid to one of zinc acetate the whole mass gelatinized, ery much like silicic acid. I t is stiff and can be cut or broken u p with tlie stirring rod. This jelly-like mass was first mashed with alcohol and then boiled with water, becoming compacted, white and flaky and easy to wash. It is sonicwhat fioluble in water when in this form, niore so in hot than in cold, separating from a hot solution on cooling i n minute crystals. Some of these crystals dried on filter paper were found to melt at 247O C. The rest of the precipitate n a s collected i n :I. crucible, dried on water-bath and weighed. On heating at :L higher temperature, 140°-170” C., slight loss in weight was iioticctl l‘liis l o w was continuous, and resulted f r o m coinxnenciiig decoiiiposition. T h e exact teniperatare a t which the decomposition cwmniencetl \\.as not determined. The salt is also easily soluble in aniniunir~m11) drate.
HEPTYLMALONIC A N D HEPTYLACETIC ACIDS.
13
The zinc was determined by dissolving in dilute hydrochloric acid a&d precipitation as carbonate. Analysis :
I. 0.1298 grm. salt taken, found $ Zn=24.49. 11. 0.0411 grm. salt taken, found $ Zn=24.33. $ Zn-24.52. Calculated for C,,H,,O,Zn HEPTTLACETIC ACID,C,H,,O,. According to the researches of Wisliceuns (Annalen, 190.26$), ethers of the aceto-acetic series can undergo two different decompositions on treatment with alkalis-one resulting in the formation of alcolol, potassium carbonate and a ketone, the second in the formation of alcohol, potassium acetate and a mono-basic acid. In preparing heptylacetic acid from the heptylaceto acetic ether the methods of Wislicerins were closely followed, yet it was found impossible to bring nbout any one decomposition unaccompanied by a partial decomposition in accordance with the second formula. In preparing the acid then, traces of niethylactyl ketone were formed at the same time. The mode of preparation was as follows. Four times the theoretical amount of a concentrated alcoholic solution of potassium hydroxide was added to the heptylaceto-acetic ether placed i n a flask connected with an inclined condenser, and the mixture heated six hours upon the mater bath. The main portion of the alcohol was then distilled off, dilute hydrochloric acid added t o the solution left behind, and the heptylacetic acid separated immediately as a brownish thick oil 011 the surface of the liquid. This oil was washed with water and dried over calcium chloride. As the heptylacetic ether could be procured with difficulty, and the product of acid from its deconiposition was very un. Asfactory, it was found more convenient to prepare the acid from 1 he heptylmalonic acid already mentioned. As is well known, all diatomic, dibasic fatty acids, which have the two carboxyles joined to the same carbon atom, fall on heating into carbon dioxide and a monatomic, monobasic acid. Thus oxalic acid (where the two carboxyls are united to one another) yields on rapid heating carbon dioxide and formic acid. Malonic acid yields carbon dioxide and acetic acid. Heptylmalonic acid, then, should yield carbon dioxide and Iicptylacetic acid. The heating was done in a small flask with condenser inclined and its open end connected with a pipette which just dipped beneath the snrface of some water
14
I1EPTYLMALOYIC A N D HEPTYLACETIC ACIDS.
in a beaker. In this way the cvoliition of carbon dioxide, and hence the progress of the reactioii, could be watched. The flask acid first was heated in a bath of 1)aratiine. The l~e~~tylninlonic melted, then at nboiit 130" C tlie el-oliitioii of carbon dioxide commenced, at 150' C' tlie evolution n-as quite rnlJi(1. The temperature was finally raised to 170" (' to coniplete the reactioii, thr. condenser \vas then inverted a n d the dark oily fliiicl left i n the flask fractioned. Vp to 12c)" C iiothing, tlistilletl over, tlien .I. f e w i l r o l ~to 22E' C', and the greqter part of the acitl ennie o ~ e at r ? 3 P - 2 X 3 C. Tlie pure acid was found to boil a t '?3:3' C. It is n colorle-. oily liquid, with somewhat of tlie cliaracteristic smell of the acetic ether
