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672 



II. " Remarks on Organo-Metallic Bodies ; 4th Memoir." By 
Edwabd Fbankxand, Ph.D., F.R.$ V Lecturer on Che- 
mistry at St. Bartholomew's Hospital. 

(Abstract.) 

In a former Memoir* the author described the production of a 
new series of organic compounds containing the metal tin in com- 
bination with the radicals methyl, ethyl, and amyl. His attention 
was at that time especially directed to the compound formed by the 
union of tin with ethyl, and to which the name stanethyl was given . 
The iodide of stanethyl was prepared by exposing iodide of ethyl to 
light or heat in the presence of tinfoil ; and, by acting with zinc upon 
the aqueous solution of this iodide of stanethyl or of the chloride of 
the same body, stanethyl itself (C 4 H 5 Sn) was obtained. 

In accordance with a theory of the constitution of all organo- 
metallic bodies which the author then suggested, the above com- 
pounds were respectively represented as the analogues of the pro- 
tiodide and biniodide of tin, thus— 

Sn I Sn(C 4 H„) 

Stannous iodide. Stannous ethide. 

Stannic iodide. Stannic ethiodide. 

It is evident that the application of this theory to the above 
bodies would receive considerable additional support if the second 
equivalent of iodine in the stannic iodide could be replaced by ethyl, 
or some other analogous organic group. In the Memoir already 
alluded to, it was mentioned, that in studying the behaviour of 
stanethyl under the influence of heat, evidence was obtained of the 
existence of this very compound, — stannic ethide, or binethide of 
tin, as it was then named. This body obviously bears the same re- 
lation to stannic iodide as stanethyl bears to stannous iodide. 

Mi 1 Sn {ciHi 

Stannic iodide. Stannic ethide. 

* Transactions of the Royal Society for 1852, p. 418. 



673 

Although there could be little doubt of the formation of stannic 
ethide by heating stanethyl to 150° C, yet the author could not suc- 
ceed in obtaining the former body in a state of purity from this 
source : it seemed probable, however, that stannic ethiodide would 
be easily converted into stannic ethide by bringing it into contact 
with zincethyl ; and a preliminary experiment completely realized 
this expectation. The results of this reaction, together with its ex- 
tension to other analogous organo -metallic compounds, form the sub- 
ject of the present Memoir. 

I. Action of Zincethyl upon Iodide of Stanethyl. 

About two ounces of crystals of iodide of stanethyl were gradually 
added to a strong solution of zincethyl in ether, care being taken to 
preserve an excess of zincethyl. On submitting the resulting syrupy 
liquid to distillation, it began to boil at 70° C. ; but the thermo- 
meter rapidly rose to 180° C, between which temperature and 
200° C. the greater part of the product passed over, solid iodide of 
zinc containing a little zincethyl being left in the retort. The di- 
stillate was washed with dilute acetic acid, and the dense ethereal 
liquid which separated was dried over chloride of calcium, and recti- 
fied. The greater portion of it distilled at 181°, and was collected 
apart. Submitted to analysis, it yielded results leading to the 

formula — 

C.EL 



Sn \ C 4 H 5 

The following equation, therefore, expresses the action of zinc- 
ethyl upon iodide of stanethyl : — 

8n(C 4 H,)n fSn(G 4 H 5 ) 2 
Zn(C 4 H 5 ) ]-\ Znl 

Stannic ethide or binethide of tin is a limpid colourless liquid even 
at — 1 3° C, possessing a very faint ethereal odour, resembling that of 
oxide of stanethyl, and a slightly metallic, though not unpleasant 
taste. Its specific gravity is 1 • 1 87 at 23° C. A determination of the 
specific gravity of its vapour gave the number 8'021, showing that 
stannic ethide consists of one volume of thin vapour and four volumes 
of ethyl, the five volumes being condensed to two. Stannic ethide 
boils at 181° C, and distils unchanged, thus differing from stannous 
ethide, which decomposes at 150°, chiefly into metallic tin and 



674 

stannic ethide, a reaction calling to mind the behaviour of stannous 
oxide when boiled with a caustic alkali. Stannic ethide is inflam- 
mable, burning with a lurid flame fringed with deep blue and evol- 
ving white fumes of stannic oxide. In oxygen it burns much more 
brilliantly, with a white light fringed with blue. 

It was important to ascertain the deportment of stannic ethide 
with negative elements, since, if it were found to be capable of direct 
combination, its analogy to inorganic stannic compounds would be, 
to a great extent, disproved. Like zincethyl, however, stannic ethide 
is incapable of combining with any other element without the expul- 
sion of at least an equivalent amount of its ethyl. Treated with 
iodine, the latter dissolves with a deep brown colour, which, how- 
ever, gradually disappears ; and if the addition of iodine be con- 
tinued until decolorization be no longer effected, the resulting 
liquid, on being submitted to distillation, is found to consist of iodide 
of ethyl, which distils over, and an iodine salt, possessing the un- 
bearably pungent odour of one of the products of the action of tin 
upon iodide of ethyl at 160°C, and described by MM. Cahours 
and Biche as iodide of distannous ethyl, Sn 2 (C 4 H 5 ) 2 I. The iodine 
salt appears, in fact, to be either identical with this body or to consist 
of stannic iodotriethide (Sn 2 (C 4 H 5 ) 3 1)*. 

Stannic ethide does not decompose water, and is not acted upon 
by strong aqueous hydrochloric acid in the cold. When, however, 
heat is applied to the mixture of the two liquids, bubbles of gas are 
slowly evolved ; but it requires from twelve to eighteen hours to 
complete the reaction. The gas was found to be pure hydride of 
ethyl, and the quantity evolved was such as to show that exactly 
one equivalent of ethyl was expelled in the form of hydride from two 
equivalents of stannic ethide, indicating the following reaction : — 

2Sn(C 4 H,),l _ |C 4 H,H 

HC1 / - \Sn a (C i H„),Cl. 

II. Action of Zincmethyl upon, Iodide of Stanethyl. 
About three ounces of crystallized iodide of stanethyl were gra- 

* Whilst I was engaged with these experiments, Mr. Buckton announced the 
formation of stannic ethide. (Proceedings of the Royal Society, vol.ix. p. 315), ami 
mentioned his intention to study the salts formed by the action of iodine, bro- 
mine, &c, upon that bod\ ; I have not, therefore, prosecuted the inquiry further 
in this direction. 



675 

dually added to a solution of zincmethyl in ether. Considerable heat 
was evolved, and the vessel in which the reaction was performed 
required to be plunged into cold water. On treating the product 
as before described, a liquid was obtained boiling between 143° and 
148° C, and yielding, on analysis, numbers closely corresponding 
with the formula 



The action of zincmethyl upon iodide of stanethyl may therefore 
be thus expressed : — 



ZnC 2 H 3 J [ Zn I- 

The new body thus formed, and for which I propose the same 
stannic ethylomethide, is a colourless limpid liquid, undistinguish- 
able in appearance from stannic ethide. It possesses, like the latter, 
a very faint ethereal odour and a slightly metallic taste. Its specific 
gravity is 1-2319 at 19°C. It does not solidify at -13° C. 
Stannic ethylomethide boils between 144° and 146° 0. The specific 
gravity of its vapour is 6*838, showing that its constitution is similar 
to that of stannic ethide. It is easily inflammable, and exhibits the 
same deportment as stannic ethide with chlorine, iodine, and bro- 
mine ; its combination with these elements being always attended 
with the expulsion of methyl. Stannic ethylomethide dissolves 
iodine, assuming a magnificent crimson colour, which disappears 
with extreme slowness unless heat be applied. When, however, 
action has once been set up, it goes on with considerable rapidity, 
even in the cold. The products of this reaction were proved to be 
iodide of methyl and iodide of distanethyl : — 

f2C 2 H,I 
' H 5 
H, 



{ 3 c i h *} = HI 



Iodide of distanethyl, which has already been partially examined, 
although with discordant results, by M. Lowig and by MM. Ca- 
hours and Eiche, is a dark straw-coloured, somewhat oily liquid, 
which does not solidify at — 13° C. It possesses an extremely pun- 
gent and intolerable odour, resembling oil of mustard. Its specific 
vol. ix. 2 z 



676 

gravity at 15° C. is 2-0329. At 208° C. it enters into ebullition, but 
cannot be distilled without decomposition. 

Treated with hot hydrochloric acid, stannic ethylomethide is de- 
composed, yielding a crystallisable salt and a gaseous mixture, con- 
sisting of — 

Hydride of ethyl 81-21 

Hydride of methyl 18 - 79 

100-00 

III. Action of Zincethyl upon Iodide of Mercurymethyl. 

The formation of stannic ethylomethide in the manner just de- 
scribed, encouraged the author to attempt a similar reaction with 

f C H 
iodide of mercurymethyl, Hg \ \ 3 . Mr. Buckton's announce- 

f C H 
ment* of the formation of mercuric ethide, Hg \ p A tt 3 , by an ana- 
logous reaction, tended also to strengthen the hope that a mercuric 
ethylomethide might be thus obtained. 

Iodide of mercurymethyl is readily acted upon by zincethyl, but 
no mercuric ethide was produced, the reaction being expressed by 
the following equation :— - 

Hg(C 2 H 3 )I| _I£ n g &W 
2Zn(C 4 H 5 ) J ~" 1 z" I 

IV. Action of Zincmethyl upon Chloride of Mercury ethyl. 

Although the above reaction failed to produce mercuric ethylo- 
methide, it was still possible that this body might be formed by 
acting upon a mercuryethyl compound with zincmethyl. About 
five ounces of chloride of mercurous ethyl (Hg (C 4 H 5 ) CI) were 
added to four ounces of a strong ethereal solution of zincmethyl. 
Considerable heat was evolved ; and after forty-eight hours the pro- 
duct was distilled. All the volatile portion came over below 140° C. 
The distillate was washed with weak acetic acid, dried over chloride 
of calcium, and then rectified. A considerable portion distilled be- 
tween 127° and 137° C, and was collected apart. The last few 
drops came over at 156° C. Repeated rectifications of the product 

* Proceedings of tlie Royal Society, vol. ix. p. 3J2. 



677 

boiling between 12 7° and 137°C. did not serve to isolate any portion 
of the distillate, having a fixed boiling point ; on the contrary, it 
was evident that the range of the temperature of distillation became 
wider each time the operation was repeated. A section boiling be- 
tween 127° and 133° gave, on analysis, 13"68 per cent, of carbon, 
whilst another section, boiling between 141° and 143°, gave 16'71. 

p 4 Ti 5 re 1 uu " es 14' 75 per cent, of carbon. Mer- 
curic methide boils at 96°, and mercuric ethide at 159° C. ; con- 
sequently mercuric ethylomethide might be expected to boil at about 
128°. The author considers it more than probable that mercuric 
ethylomethide was formed in the above reaction ; but subsequent 
distillations gradually transformed it, more or less perfectly, into a 
mixture of mercuric ethide and mercuric methide. 



H _rc 4 H,i _ riig(c 4 H 5 ) 2 

U8 lC 2 H 3 /-iHg(C 2 H 3 ) 3 . 



V. Action of Zinc upon a Mixture of the Iodides of Ethyl and 
Methyl. 

In a former memoir* the author pointed out that the vapour 
volume of zincethyl indicated the constitution of that body to be 

C H 1 

represented by the formula p 4 tt 5 [ Zn 2 ; but it is evident that this 

formula would receive important confirmation if the double equiva- 
lent of zinc could be made to combine with two radicals of different 
composition. An attempt was made to produce such a body by 
submitting simultaneously the iodides of methyl and ethyl, mixed 
with an equal volume of ether, to the action of zinc at 100° C. In 
eighteen hours the decomposition of the iodides was complete, and 
the distilled product, on being rectified, began to boil at 38°, ether 
and zincmethyl distilling over ; the thermometer then gradually and 
uniformly rose to 120°C, at which temperature the remainder of 
the product, consisting of pure zincethyl in considerable quantity, 
distilled over. No evidence whatever was obtained of the existence 
of an intermediate compound containing both ethyl and methyl. 

* Transactions of the Royal Society for 1855, p 266. 

2 z 2 



678 



VI. Zincmethyl. 

The experiments detailed in the foregoing psges requiring the use 
of considerable quantities of zincmethyl, the author's attention was 
directed to the preparation of this body in much larger quantities 
than could be obtained by the operations in sealed glass tubes pre- 
viously described by him. He found that the preparation of a strong 
ethereal solution of zincmethyl succeeded most satisfactorily in a 
copper digester, heated to 100° C. ; in fact, the decomposition by 
zinc of an ethereal solution of iodide of methyl is much more quickly 
and perfectly effected than that of a similar solution of iodide of 
ethyl ; but on submitting the product to rectification, a liquid was 
obtained boiling at about 51° C, spontaneously inflammable to the 
last degree, and possessing the intolerable odour of zincmethyl. 
On analysis, however, it yielded numbers closely agreeing with the 
formula — 

The specific gravity of its vapour was 3' 1215, a number which does 
not correspond with the theoretical specific gravity of a compound of 
the above formula, unless the exceedingly improbable assumption be 
adopted, that it contains two volumes of zincmethyl vapour, united 
with one volume of ether vapour, without condensation. On the 
other hand, it accords closely with the specific gravity of the vapour 
of a mixture of zincmethyl and ether in the above proportions. 

Without at present offering any decided opinion as to the nature 
of this body, the author states that in repeated operations with large 
quantities of materials he has entirely failed in obtaining pure zinc- 
methyl by this method of proceeding. 

Similar repeated attempts to produce pure zincethyl from zinc 
and iodide of methyl, without the intervention of ether, were also 
unsuccessful, although this method generally succeeds in small glass 
tubes. This anomaly in the results obtained from the same mate- 
rials heated in a copper digester and in glass tubes, is doubtless due 
to the difference of the conditions in the two cases. In a glass tube 
half immersed in a heated oil bath, a constant distillation of the 
internal liquid is going on, the liquid condensed in the upper por- 
tion of the tube flowing over an extensive surface of zinc in its 



679 

descent ; whilst, in a digester of thick copper, the different parts 
of the vessel, owing to the high conductivity of the metal, are main- 
tained at so uniform a temperature as to prevent any such circulation 
of the liquid from taking place. 

The body just described being regarded as a mere mixture of zinc- 
methyl and ether, incapable of being separated on account of the 
close proximity of their boiling points, a more successful result was 
anticipated by mixing the iodide of methyl with methylic ether in- 
stead of vinic ether. As methylic ether boils at — 21° C, it was 
thought that no such difficulty of separation could arise ; the bodies 
employed would then, in fact, be exactly homologous with those so 
successfully used in the preparation of pure zincethyl on the large 
scale. It was found, however, that although a large quantity of 
zincmethyl was produced, yet it was impossible to obtain it free from 
methylic ether. A large portion of the product boiled at 43°, a 
small residuum only distilling between this temperature and 48° ; 
both portions yielded, on analysis, results approaching the formula 



KSh^Kh:} *- 



This result is, therefore, homologous with that obtained by the de- 
composition of iodide of methyl mixed with vinic ether. 

In conclusion, the author states, that after an expenditure of many 
pounds of iodide of methyl, he has been unable to obtain even the 
smallest quantity of pure zincmethyl by the use of a copper digester, 
although a much larger product of the ethereal solution is obtained 
than in the corresponding preparation of zincethyl. 

March 10, 1859. 
Sir BENJAMIN C. BRODIE, Bart., President, in the Chair. 
The following communications were read : — 

I. Letter from James P. Muirhead, Esq., to Sir Benjamin 
C. Bkodie, Bart., Pres. K.S., dated March 8, 1859, re- 
lating to the Discovery of the Composition of Water. Com- 
municated by Sir B. C. Bkodie. 

I have now, with your permission, to request you to lay before the