FIG. 3.

प

"Crystalline System.-Orthorhombic.

a:b:c=1.4654:1:0.9501.

"Forms observed.-c{001}, p{110}, q{011}, r{101}.

"The following angular measurements were obtained.

"The plane c(001) is the optic axial plane, and an optic axis emerges obliquely through each face of the form p{110}; the double refraction is strong and the optic axial dispersion slight. After melting, the substance solidifies readily, and is thus obtained in large individual flakes, which are often marked by striæ crossing each other at about 60°, and cracked across their longest dimension on cooling; the flakes are frequently perpendicular to an optically negative bisectrix of a large axial angle."

Methylic -Bromocamphanate, COOMe C,H,,Br

12

This ethereal salt is conveniently prepared by passing hydrogen chloride into a solution of the acid in methylic alcohol and then

evaporating at the ordinary temperature; the product, which is slowly deposited in felted needles, can be purified by recrystallisation from a mixture of ether and chloroform.

0-1662 gave 0-2777 CO2 and 0.0832 H2O. C=45·57; H=5·56. C11H15 BrO requires C=45-36; H=5.15 per cent.

Methylic π-bromocamphanate crystallises from ether and from most other solvents in long, transparent needles melting at 87-88°; it is very readily soluble in cold chloroform, methylic alcohol, and boiling ether, but comparatively sparingly soluble in light petroleum. Massive crystals are easily obtained from a solution in a mixture of ether and chloroform, and a specimen of the compound thus obtained was examined by Mr. W. J. Pope, whose report is now given.

"The crystals of methylic bromocamphanate are transparent orthorhombic plates or prisms, possessing a high lustre (Fig. 4); the habit of the crystals varies considerably, those of prismatic habit are lengthened in the direction of the axis-a, and somewhat flattened in that of the b-axis, the dominant forms being a{100} and r{101}; the tabular crystals are flattened on two parallel faces of the form r{101}. Very good results are obtained on measuring the crystals.

FIG. 4.

go

"Crystalline System.-Orthorhombic.

a:b:c=1.0977:1:0.6561.

“Forms observed.—a{100}, b{010}, p{110}, r{101}.

"The following angular measurements were obtained.

"There is a poor conchoidal cleavage parallel to b{010), and the axis-b is the acute bisectrix; the optic axial plane is c(001), and the double refraction is positive in sign, and strong. The optic axial angle is fairly large and the optic axial dispersion is slight.

"The substance solidifies readily after melting on a microscope slide under a cover slip, giving large, individual flakes; most of these are nearly perpendicular to an optically negative bisectrix of a very large optic axial angle, and these are full of symmetrically arranged eggshaped bubbles and of intersecting striations. A few fragments are usually to be observed which show no bubbles or striæ; these are nearly perpendicular to the optically positive bisectrix of a fairly large optic axial angle. This modification is doubtless identical with the crystals measured above."

Methylic -bromocamphanate is slowly attacked by concentrated aqueous ammonia at ordinary temperatures, and is thereby converted into a crystalline substance, which, judging by its melting point and other ordinary properties, is identical with the T-bromocamphanamide produced by the action of aqueous ammonia on ww-dibromocamphoric anhydride. This compound may now be described.

π-Bromo-w camphanamide, NH, CO·C2H12Br<

CO

When finely divided w-dibromocamphoric anhydride is left in contact with concentrated aqueous ammonia at ordinary temperatures, it slowly changes into a rather more bulky mass of small prisms, but without passing into solution to any noticeable extent; after keeping the mixture for about two days, the product is separated by filtration from the ammoniacal solution, which contains a small quantity of a readily soluble, crystalline, ammonium salt, washed with cold water, and recrystallised from dilute methylic alcohol. The substance obtained in this way is the amide of -bromo-w-camphanic acid, and an analysis of it gave the following result.

0.1678 gave 0.2671 CO2 and 0·0796 H2O. C=43·41; H=5·27. C10H140,BrN requires C = 43·47; H=5.07 per cent.

The nature of this compound is further established by the fact already mentioned, namely, that it is formed on treating methylic 7-bromocamphanate with aqueous ammonia, and also by its behaviour on bydrolysis; when boiled for a short time with concentrated hydrochloric acid, it is converted into a crystalline acid, which melts at 176-177°, and has all the properties of T-bromocamphanic acid.

T-Bromo-w-camphanamide crystallises from most solvents in lustrous, transparent needles or prisms melting at 161-162°; it is very readily

soluble in cold chloroform, acetone, ethylic acetate, acetic acid, and most other solvents, and it also dissolves freely in boiling water, but it is insoluble, or nearly so, in a cold dilute solution of sodium carbonate. It seems to be dimorphous, as the transparent crystals deposited from dilute methylic alcohol become opaque at about 140° when slowly heated, and do so at even lower temperatures when the tube containing them is rubbed gently.

Formation of -Bromocamphanic Acid from π-Bromo-w-chlorocamphoric Anhydride. It was stated in the introduction that -bromo-w-chlorocamphoric anhydride is decomposed by boiling water, giving hydrogen chloride, and an acid identical with the T-bromo-w-camphanic acid, prepared in a similar manner from Tw-dibromocamphoric anhydride; this statement rests on the following experimental evidence.

When bromochlorocamphoric anhydride is boiled for some hours with diluted acetic acid, and the filtered solution then allowed to cool, a substance crystallising in colourless prisms is deposited; this compound, after having been purified, melted at 176-177°, and in appearance and other properties seemed to be identical with T-bromocamphanic acid. The great similarity between dibromo- and bromochloro-camphoric anhydrides, however, if repeated in the case of the bromo- and chloro-camphanic acids, might render the distinction between the two latter a matter of some difficulty; for this reason, it was necessary to make the following analysis, the results of which show that the decomposition product of the bromochloro-anhydride is really a π-bromocamphanic acid.

0-1572 gave 0.2521 CO2 and 0.0679 H2O. C=43-74; H = 4.80. C10H13BrO4 requires C=43·32; H=4·69 per cent.

Hydroxy-cis--camphanic Acid.

It has been shown in earlier papers that cis--camphanic acid is slowly oxidised by potassium permanganate in alkaline solution, being converted into a hydroxy-cis-r-camphanic acid, which is the lactone of a dihydroxycamphoric acid; this hydroxy-acid can be obtained in various ways from dibromocamphoric anhydride and its derivatives. When, for example, dibromocamphoric anhydride is boiled for some time with alcoholic potash, or fused with potash at a moderate temperature, both the bromine atoms are removed, and hydroxy-cisT-camphanic acid can be isolated from the product by methods which it is unnecessary to describe. Again, when T-bromocamphanic acid is heated with silver nitrate in aqueous solution, silver bromide is rapidly deposited, and an acid having all the properties of hydroxycis--camphanic acid can be obtained from the solution.

A number of experiments were made in the hope of isolating a

dihydroxycamphoric acid, or the corresponding dilactone; for this purpose, the dibromo-anhydride, dibromo-acid, and -bromocamphanic acid, were separately treated with aqueous silver nitrate under various conditions; in nearly every case the product seemed to be a mixture of two or three organic compounds, and it was not easily separable into its components by fractional crystallisation or by other methods; hydroxy-cis--camphanic acid was isolated in almost every instance, and also a crystalline substance, which from its melting point and other properties was found to be identical with the y-lactone of hydroxycamphotricarboxylic acid. Further, in several experiments, small quantities of an oily product were obtained; this substance, when purified, was only sparingly soluble in boiling water (the other two products are readily soluble), and apparently insoluble in cold dilute sodium carbonate; it was vigorously attacked by hot concentrated nitric acid, being converted into the y-lactone of camphotricarboxylic acid. These observations seem to show the existence of a dilactone of dihydroxycamphoric acid amongst the products of the action of silver nitrate on the bromo- and dibromo-compounds in question.

Hydroxy-cis--camphanic acid is prepared far more easily by one of these methods than by the oxidation of cis-π-camphanic acid, and its investigation, as well as that of some of the other compounds related to it, is being continued; the crystals of this acid, obtained from an acetone solution, are of large size and suitable for goniometric examination.

UNIVERSITY COLLEGE,

NOTTINGHAM.

XVII.-a-Ketotetrahydronaphthalene.

By FREDERIC STANLEY KIPPING, Ph.D., D.Sc., F.R.S., and ALFRED

HILL.

THE conversion of phenylpropionic chloride into a-hydrindone by the action of aluminium chloride under the conditions described by one of us in a previous communication (Kipping, Trans., 1894, 65, 680) is an example of intramolecular condensation by which an open- is converted into a closed-carbon chain; the reaction also provides by far the most convenient method yet known for the preparation of a-hydrindone, as, with due care, the yield is invariably very good, and phenylpropionic chloride itself can be obtained without any difficulty in almost unlimited quantity; this method of preparation was, therefore, made use of in later investigations of the derivatives of a-hydrindone (Kipping and Revis, Trans., 1897, 71, 238).