525. Choline, C5H15NO2, trimethyl ethylene hydrate ammonic hydrate:

requires more detailed notice.

OH

This strongly alkaline ammonium base was first found in the bile, later prepared under the name neurine from the brain, and also occurs widely diffused in organic nature as 'sincaline.' Neurine does not occur as such in the organism, but in combination forming lecithine, a fatty substance, which yields neurine as a product of its resolution into simpler bodies.

In order to prepare choline, ox brain is generally employed. This is finely divided, and extracted first by frequent shaking with ether and then with warm alcohol. The ether and alcohol are then evaporated off, and the residue boiled for about an hour with excess of solution of baric hydrate. Excess of baric hydrate is then removed by passing carbonic anhydride, the liquid boiled, filtered, and the clear aqueous liquid evaporated to a syrup on the water bath. This is ex tracted with absolute alcohol, the filtered solution treated with slight excess of hydrochloric acid and precipitated with platinic chloride. The clear yellow precipitate of platino-chloride is then dissolved in water, freed from platinum by hydric sulphide, and finally crystalline choline hydrochloride, N(CH3)3(C,H,.OH).Cl, obtained by evaporation in a dry vacuum. This, on treatment with moist argentic oxide, yields an aqueous solution of free neurine :

N(CH3)3(C2H4.OH)Cl + AgOH = AgCl + N(CH3)3(C2H1.OH)OH, which, on complete evaporation, forms a caustic, alkaline, difficultly soluble syrup, which absorbs water and carbonic anhydride from the air. The platino-chloride, [N(CH3)3(C2H4.OH)Cl],PtC14, crystallises from its aqueous solution in beautiful reddish yellow tables. According to some authors, the base obtained from nervous tissue is not choline, but trimethyl-vinylammonic hydrate, which they then term neurine. But, as hydrochloric acid is employed in the preparation, it may readily have occurred that trimethyl-ethylene chloride ammonic chloride may have been formed, which would yield the vinyl base when treated with argentic oxide.

Choline is obtained synthetically by the action of ethylene hydrate chloride or of ethylene oxide and water on trimethylamine:

CH2

CH2

CH2.CH2.OH

O + N(CH3)3 + HOH=N=(CH3)3

OH

On heating choline with concentrated hydriodic acid and some red phosphorus at 140° it yields trimethyl-ethylene iodo-ammonic iodide, N(CH3)3(C2H,I)I, which is also obtained from trimethylamine and ethylene diiodide. Moist argentic oxide converts it into trimethyl vinylammonic hydrate:

N(CH3)3(C2H,I)I + 2AgOH = 2AgI + H2O

+N(CH3)3CH:CH2.OH.

526. Urea Derivatives.-On heating ethylene diammonic chloride with argentic cyanate, and evaporating the filtered liquid, crystals are obtained of

This is difficultly soluble in cold water and alcohol, melts at 192°, combines with acids to form salts, and on heating with potassic hydrate yields ammonia, ethylene diamine, and potassic carbonate.

18

Diethyl-ethylene diurea, C6H1N4O2, is obtained similarly to the foregoing from diethyl ethylene ammonic dichloride and argentic pseudo-cyanate:

CH2.N(C2H)H2Cl
CH2.N(C2H5)H2Cl

+2Ag.N:CO = 2AgCl + |

CH..N(C,H,)CO.NH,

CH..N(C,H,)CO.NH,

2

It is readily soluble in alcohol, and is readily decomposed on heating with acids, yielding carbonic anhydride and salts of diethyl ethylene diamine and ammonia.

Ethylene diethyl-urea, C6H18N4O2, isomeric with the preceding, is obtained by the action of diethylene diamine on ethylic pseudocyanate:

CH..NH,
CH,NH,

+2CO.N.C2H5 =

CH..NH.CO.N(C,H,)H

CH..NH.CO.N(C,H,)H

It is insoluble in alcohol and is difficultly decomposed by strong acids, but on heating with alkalies gives carbonates, ethylamine, and ethylene diamine.

527. Ethylene dithio-urea can be obtained from ethylene diamine and carbonic disulphide in the following way (comp. § 284):-On mixing in presence of alcohol, the mixture, at first clear, solidifies to a mass insoluble in alcohol and ether, containing equal molecules of the two ingredients. On boiling the aqueous solution for a long time, hydric sulphide is evolved, and on cooling fine white crystals of bitter taste separate of ethylene sulphurea, C3H6N2S:

It yields very unstable salts with acids, but is precipitated by mercuric chloride and argentic nitrate as crystalline compounds with these salts; e.g. 2C3H6N,S,3HgCl2.

Taurine, C2H,NSO3.

528. Taurine, or ethylene-amine sulphonic acid, stands in close relationship to isethionic acid:

It is of great physiological importance. As this compound is at the same time a sulphonic acid and an amine, it can only exist as a saline compound, which may be derived from only one molecule, but more probably possesses the double formula:

Taurine is most readily prepared from the bile of animals, which contains invariably the alkaline salts of nitrogenous and sulphurcontaining acids, taurocholic acids. The latter are converted into sulphur-free acids (cholic acids) and taurine on boiling with strong acids or bases (comp. bile acids).

Taurine is also found in animal tissues, e.g. in the lungs and muscles (especially of mollusca).

It is prepared synthetically by heating ammonic ethylene chlorosulphonate with aqueous ammonia to 100°:

Taurine crystallises in large, hard, colourless prisms of the monoclinic system, without taste or odour, and which are difficultly soluble in cold, readily in hot water, insoluble in alcohol and ether. With potassic hydrate it yields potassic ethylene-amine sulphonate:

CH2.CH2

S 02. O

>NH3 + KOH = H2O +

CH,.CH..NH,

SO2.OK

which is of alkaline reaction and is soluble in alcohol.

By action of nitrous acid taurine is converted into isethionic acid, nitrogen being evolved:

Nitryl Compounds of the Olefines.

529. Compounds of the glycol radicals with nitryl, (NO2), have only as yet been obtained from the olefines by action of concentrated nitric acid or by direct union with nitric peroxide.

Ethylene dinitryl, C2H,N2O4, is most readily obtained when dry ethylene gas is passed into anhydrous ether, to which, at the same time, liquid nitric peroxide is added drop by drop:

C2H1 + N2O1 = C2H1(NO2)2.

Colourless prisms or tables of ethylene dinitryl separate, which melt at 37.5°, and volatilise at slightly higher temperature (with especial readiness in an atmosphere of ethylene gas).

Isoamylene dinitryl, C5H10(NO2)2, is obtained by passing nitric peroxide vapour into isoamylene, or isoamylene vapour into red fuming nitric acid. It crystallises in rectangular tables, which decompose at 95°, but sublime slowly below this temperature.

Phosphorus and Arsenic Compounds of Ethylene.

530. Triethyl phosphine and triethyl arsine behave towards ethylene haloids in similar manner to the trialkylamines (§ 522).

1. If triethyl-phosphine be left for a long time with ethylene dibromide at ordinary temperatures, it yields mainly Triethyl-ethylene bromo-phosphonic bromide:

C8H19PBr2 = P(C2H5)3(CH2.CH,Br)Br,

2

crystallising from water and alcohol n rhombic dodecahedrons. On addition of argentic nitrate half the bromine is precipitated, whilst the nitrate, P(C2H5)3(C2H1Br)O.NO2, remains in solution. The latter is converted by hydrochloric acid into the chloride, P(C2H5)3(C2H ̧Br)Cl, which gives with platinic chloride a difficultly soluble double salt, crystallising in long prisms.

If the original bromide be heated, either alone or with argentic salts, it loses hydrobromic acid from the ethylene bromide group, and yields derivatives of triethyl-vinyl phosphonium; on heating to 240°, e.g., a residue of triethyl-vinyl phosphonic bromide, P(C2H ̧)з(C2H2)Bг,

remains.

If, on the other hand, the first bromide be heated in dilute solution with argentic oxide, both bromine atoms are replaced by hydroxyl, and the strongly alkaline base triethyl-ethylene hydrate phosphonic hydrate, P(C2H5)3(CH2.CH2.OH)OH, is obtained.

2. An excess of triethyl-phosphine is converted by ethylene dibromide into

crystallises in colourless needles readily soluble in alcohol and water. By moist argentic oxide it is converted into

Hexethyl-ethylene diphosphonic dihydrate, |

CH2.P(C2H5)3OH

a

strongly caustic, deliquescent mass. Triethyl-ethylene bromide phosphonic bromide also gives analogous derivatives with trialkyl phosphines:

531. The latter reaction can be employed for the preparation of compounds containing both phosphorus and nitrogen:

&c.

Triethyl-trimethyl ethylene phosphammonic dibromide.

532. Triethylarsine behaves towards ethylene dibromide in similar manner, and yields arsonic derivatives analogous to the phosphonic derivatives (§ 530):

of which the first unites directly with ammonia, amines, and phosphines; e.g.

Triethyl-ethyl ethylene arsammonic dibromide.

Triethyl arsine also unites directly with triethyl-ethylene bromide phosphonic bromide :

533. Glycol derivatives corresponding to the large group of metallic compounds of the monad alcohol radicals are not known. Their preparation has in part been attempted without result. Only ethylene forms some derivatives in which it is at least in part united to metals, especially platinum and iron.

Ethylene platinum chloride, C,H,PtCl2, is formed by heating a solution of platinic chloride with alcohol, or by passing ethylene gas into a hydrochloric acid solution of platinous chloride:

It is a clear yellow mass, whose aqueous solution yields compounds with ammonic and potassic chlorides, crystallising in rhombic prisms.