from plants not yet determined, and is obtained therefrom by crystallisation from a hot aqueous solution.

Synthetically dulcite has been obtained by addition of hydrogen to lactose, by treatment of a solution of the latter with sodium amalgam.

Dulcite crystallises in large monoclinic prisms, melting at 188°— 190°, which require 38 parts of water at 14° for solution. It is but little soluble in alcohol. By oxidation with nitric acid it yields mucic acid. The chemical behaviour of dulcite is very similar to that of mannite.

By heating with hydrochloric or hydrobromic acids it gives dihaloid tetrahydrates, crystallising in plates, which are but little soluble in water, and of which CH ̧Cl2(OH), melts with decomposition at 180°.

With nitric and sulphuric acids dulcite yields nitrodulcite, CH(O.NO2)6. By heating to 180° with four times its weight of acetic anhydride it gives the hexacetate, CH,(O.C2H3O), crystallising in small brittle plates, melting at 171°. Heated to solution with 1 part of acetic anhydride and some glacial acetic acid, dulcite yields scales of a diacetate, CH(OH)2(O.C2H,O)2, melting at 176°; with acetic acid only it gives the dulcitan salts:

CH2O(OH)2(O.C2H2O)2,

2 3

as an oily liquid, and C,H,O(O.C2H2O), as a very bitter, resinous mass. By heating the latter with a molecule of acetic anhydride it is transformed into the hexacetate of dulcite.

Chlor-acetyl converts dulcite into the crystalline pentacetate chloride, CH,Cl(O.C2H2O)5, converted by water into

CH(OH)(O.C2H3O)5,

crystallising in needles of melting point 165°.

852. A third isomeric of mannite, sorbite, C6H1206, occurs in the berries of the mountain ash (Sorbus aucuparia), and is found, as it is not fermentable, in the wine prepared from these by fermentation. It forms crystals containing molecule of water. In the dry state it melts at 110°-111°.

Isomerides of Mannitan.

853. Crystalline bodies isomeric with mannitan are found in several plants; their constitution must, however, be different, as no union with water and conversion into compounds of the mannite formula has been observed.

Pinite, C6H1205, occurs in the exudations of the Californian pine Pinus lambertiana. It forms hard, warty crystal masses of intensely sweet taste, which melt at 150° and whose solution rotates the plane of polarisation to the right.

Isodulcite, C6H12O5,H2O, is obtained, together with quercetin, by boiling quercitrin with dilute mineral acids. It forms large transparent crystals, which are readily soluble, and melt at 105°-110° with loss of their water of crystallisation.

495

DERIVATIVES OF THE HEPTAVALENT HYDROCARBON NUCLEUS, CnH2n-5

MONOBASIC ACIDS OF THE SERIES CnH2n-102.

854. Acids of this series, CnH2n--50.OH or CnH2n' – 3.CO.OH, are mostly prepared by the action of excess of alcoholic potassic hydrate on the halogen addition products of the members of the acryl oleic acid series :

CnH2n-1Br2CO.OH + 3KOH = 2KBr + 3H2O
+CnH2n-3.CO.OK,

or, what comes to essentially the same thing, on the first halogen substitution products of those acids :

CnH2n2Br.CO.OH+2KOH= KBr + 2H2O + CnH2n'- 3.CO.OK. In the carbon residue united to CO.OH either double union of neighbouring carbon atoms occurs twice, or else one triple union occurs, so that the acids can unite directly with four atoms of halogen.

By action of nitric acid the higher members of the series similarly unite with two atoms of oxygen, and yield monobasic acids of the formula CH2n-404, which further yield first half-aldehydes and later acids of the succinic series, whose carbon contents is equal to half that of the acid CnH2n-404:

CnH2n-404 +30= CH2-204 + CH2-203.

855. Tetrolic acid, С4H4O2 or С ̧H,CO.OH. Either

2

CH,.C;C.CO.H

or CH2:C: CH.CO.OH is formed by heating chlor a-crotonic acid with alcoholic potassic hydrate on the water bath, and is obtained from the potassic salt first formed:

CH3.CCI: CH.CO.OK + KOH = KCl + H2O + C3H3.CO.OK, by addition of sulphuric acid, and extracted from the aqueous solution by shaking with ether, and also by the action of carbonic anhydride on sodium allylene, CH3.C: CNa. It crystallises in rhombic tables, deliquescing in air, is also soluble in alcohol and ether, and melts at 76.5° and boils at 203°.

856. Sorbic acid, C6H ̧O2 = CH7.CO.OH, is obtained from the juice of unripe berries of the mountain ash by distillation, and passes over with the vapour of water as a yellow oil. This oil, on heating

with solid potassic hydrate and acidulation, or by long boiling with strong hydrochloric acid, yields solid sorbic acid. It crystallises in long colourless needles, very difficultly soluble in cold, more readily in hot water and in alcohol, and melts at 134.5°. Although not distillable unchanged alone it passes over in the vapour of water. Its baric salt, (CH7.CO.O),Ba, crystallises in silvery scales, which are readily soluble.

Ethylic sorbate, C,H,CO.O.C,H,, prepared by saturating the alcoholic solution of the acid with hydrochloric acid, is an oil of aromatic odour boiling at 195.5°.

Sorbic acid unites with nascent hydrogen, forming hydrosorbic acid ($ 798, 2), with bromine, according to the quantity of the latter, either to form the dibromide, CH,Br2.CO.OH, crystallising in small brilliant plates and melting at 94°-95°, or the tetrabromide, CH,Br1.CO.OH, or tetrabrom-hexylic acid, which is difficultly soluble in water, melts at 183°, and yields salts with the alkalies, barium, calcium, and zinc, which mostly crystallise in brilliant plates and decompose on boiling.

857. Palmitolic acid, C16H28O2 = C15H2,CO.OH, is obtained by heating hypogacic acid and gaidic acid dibromides (§ 799) with alcoholic potassic hydrate, and decomposition of the aqueous solutions of the potassic salt formed by mineral acids. It crystallises from alcohol and ether in fine silky needles, insoluble in water, melting at 42°, and combining directly with bromine to form the bromides C16H28Br2O2 and C16H28Br4O2.

Fuming nitric acid converts palmitolic acid into palmitoxylic acid, C15H27O2CO.OH, crystallising in plates and melting at 67°, and further oxidises the latter with resolution into suberic aldehydic acid, CH1403 (§ 782), and suberic acid, CH140 (§ 841).

4

Stearolic acid, C18H32O2 = C17H31.CO.OH, is obtained from the dibromides of oleic and elaidic acids in long colourless prisms, melting at 48°, which are little soluble in cold alcohol. It volatilises without decomposition. Its salts are mostly crystalline, those of the alkalies having the properties of soaps. It does not unite with nascent hydrogen, but gives with bromine a liquid dibromide:

C18H31 Br2O.OH

and a crystalline tetrabromide, C18H3, Br,O.OH, which melts at 70°. Nitric acid converts stearolic acid into stearoxylic acid:

This crystallises in brilliant plates, melting at 86°. Further action of the oxidising agent converts it, with decomposition of the molecule, into azela-aldehydic acid, C,H1603, and azelaic acid, C9H1604.

Behenolic acid, C22H40O2 = C21H39.CO.OH, obtained by action of alcoholic potassic hydrate on erucic acid dibromide at 150° and on brassic acid dibromide at 210°-220°. It crystallises from alcohol in tufts of needles, melting at 57.5°, and gives crystalline bromides with two and four atoms of bromine. Concentrated nitric acid converts it into behenoxylic acid, C2H3902.CO.OH, brilliant plates melting at 90°-91°, brassylo-aldehydic acid, C11H2003, and brassylic acid, C11H2002.

11

DERIVATIVES OF THE RADICALS OF DIBASIC HYDROXY-ACIDS.

858. The compounds of this series are mostly dibasic acids, which are derived from the acids of the series CnH2n.(CO.OH)2 by substitution of halogen, hydroxyl, &c., for a hydrogen atom. The hydroxyl derivatives, CnH2n' - 1(OH)(CO.OH)2, therefore, bear the same relation to these dibasic acids as that of the glycollic to the fatty acids.

Tartronic Acid, C3H,O, CH(OH)(CO.OH)2.

4

859. Tartronic or hydroxy-malonic acid was first obtained by evaporating an aqueous solution of dinitro-tartaric acid :

CH(O.NO2).CO.OH

CH(O.NO2).CO.OH

= CO2 + N2O3 +

CO.OH

CH(OH).CO.OH

it is also formed by the action of nascent hydrogen on mesoxalic acid : .CO.OH

CO.CO.OH

.CO.OH

+ 2H=CH(OH) CO.OH

and by the oxidation of grape sugar by an alkaline copper solution. It crystallises in large colourless prisms, melting at 180°, with evolution of water and carbonic anhydride, and leaving an amorphous residue of glycollide (§ 713):

860. Chloral cyanhydrin is a derivative of the same carbon nucleus; it is obtained by the action of hydrocyanic acid on chloral hydrate:

CC13.CH(OH)2 + HCN = H2O + CC13.CH(OH).CN.

It crystallises in colourless prisms, melting between 60° and 61°, and is decomposed by alkalies into chloroform and metallic formate and cyanide.

Trichlor-lactic acid, CC13.CH(OH).CO.OH, obtained by the action of aqueous acids on chloral cyanhydrin, is another derivative of the same carbon nucleus; it is crystalline and melts between 105° and 110°. Its salts readily decompose into formates and chloral:

CC13.CH(OH).CO.ONa = CC13.CHO+CHO.Ona.
Ethylic trichlor-lactate forms plates melting between 66° and 67°.

Malic Acid, C4H605 = C2H2(OH)(CO.OH)2.

861. Three isomeric acids are possible of this formula:

CH2.CO.OH

CH(OH).CO.OH

.CO.OH

.CO.OH

, CH3.C(OH)
I) CO.OH, and CH(OH)CH CO.OH

So far only two are known, which, however, appear not to be structural but physical isomers. One of them, natural malic acid, rotates

K K

the plane of polarisation to the right, whilst the artificial is optically inactive. Both of them are converted into ordinary succinic acid by heating with hydriodic acid, and must, therefore, correspond to the first of the three formulæ above given.

Natural or optically active malic acid occurs very widely disseminated in the vegetable juices, in the free state in sour apples, unripe grapes, and especially in quinces and unripe mountain ash berries.

.co.o

It is best prepared from the boiled and filtered juice of the latter, which is then nearly saturated with milk of lime, so that it only possesses a feebly acid reaction. On continued boiling calcic malate, .CO.O C2H(OH)CO.O Ca, H2O, precipitates as a nearly insoluble crystalline powder. This is then added as long as it still dissolves to nitric acid diluted with ten times its weight of water. On cooling large brilliant, transparent crystals, difficultly soluble in water, of hydric .CO.OH calcic malate, [C2H(OH) COO2Ca,8HO, separate; these are dissolved in hot water and precipitated with plumbic acetate. The washed, insoluble plumbic salt, C2H,(OH)(CO.O), Pb, is then suspended in water, decomposed by hydric sulphide, and the filtered liquid evaporated.

Malic acid crystallises only difficultly in cauliflower-like aggregates, which deliquesce in acid. It melts at below 100° and decomposes at 150°, or on long boiling with hydrochloric acid, into water and fumaric acid:

=

C2H3(OH)(CO.OH), H2O + C2H2(CO.OH)2.

Phosphoric chloride converts it into fumaric dichloride, C2H2(CO.Cl)2. Its aqueous solution rotates the plane of a polarised beam of light somewhat to the left (specif. rotation - 5°). By heating with hydrobromic acid it is converted into brom-succinic acid:

C2H3(OH)(CO.OH)2 + HBr = H2O + C2H3Br(CO.OH)2 ; with strong hydriodic acid it yields ordinary succinic acid:

C2H(OH)(CO.OH)2 + 2HI= H2O + I2 + C2H1:(CO.OH)2. Chromic acid converts malic acid into malonic acid (§ 830); putrefaction ferments convert it into carbonic anhydride, acetic succinic (§ 833) and butyric acids. Fusing with potassic hydrate decomposes it into acetate and oxalate :

CH(OH)CO.OK

CH2.CO.OK

+ KOH CH3.CO.OK + KO.CO.CO.OK + H2.

The alkaline malates are readily soluble, all others difficultly soluble; all are crystalline.

Diethylic malate, C2H3(OH): (CO.O.C2H)2, is obtained by saturating an alcoholic solution of malic acid with hydrochloric acid. The liquid, after standing for a long time, is neutralised with sodic hydrate and shaken with ether. On evaporation of the solution diethylic malate is obtained as a liquid soluble in alcohol, ether, and also in water, the latter soon decomposing it into alcohol and malic acid.