COMBINATION OF DRY CARBON MONOXIDE AND OXYGEN. 361

XXXIV.--InJluence o f the Nasceylt State o n the Combina- tion of D r y Carbon Monoxide and Oxygen.

By EDWARD JOHN RUSSELL.

So large a number of pairs of substances are known which require the presence of traces of a third substance before they will combine, that there does not seem much reason for adding to their number in the present state of our knowledge. It is, however, both of interest and of importance to find out how far the action of the third substance is modified when the conditions are varied; when, for example, high temperatures are introduced, or one of the pair of substances is in the nascent condition. Some experiments bearing on this form the sub- ject of the present communication. The example chosen for investiga- tion was the very well known one of carbon monoxide and oxygen.

Some time ago, it was shown by Professor Dixon and the author (Trans., 1897, 71, 605) that when carefully dried mixtures of carbon monoxide with excess of chlorine peroxide were sparked, an explosion took place, but a large part of the carbon monoxide was not affected thereby, and the chief reaction was simply the ordinary explosive decomposition of chlorine peroxide, thus :

2c10, = c1, + 20,.

Although an excess of oxygen was present in the nascent condition and at a high temperature, it nevertheless failed to attack more than one-half to one-third of the carbon monoxide present,

The author has since studied several other reactions in which carbon monoxide and oxygen are brought together in the flame of an explosion, one of them being in the nascent condition.

It is not possible to completely separate the two factors nascent condition and high temperature, because the nascent state implies that a reaction is going on; and a reaction that proceeds with explosion develops a considerable amount of energy. The amount of energy developed can be varied, however, by varying the reaction, and, by keeping the nascent condition constant, some idea can be obtained of the relative influence of the two factors.

The substances used as sources of nascent oxygen were chlorine monoxide and chlorine peroxide; and, as sources of nascent carbon monoxide, carbonyl sulphide, and nickel carbonyl.

I. Interaction of Oxygen and iVascent Carbon Mmoxide.

(a) Combustion of Carbony2 8u&hide.--Than showed in 1867 (Annoten, Suppt., 5, 236) that when carbonyl sulphide is passed through a heated

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362 RUSSELL: lNFLUENCE OF THE NASCENT STATE ON THE

tube, it decomposes into carbon monoxide and sulphur. Berthelot (Conzpt. rend., lS7S, 87, 573) mentions a second decomposition repre- sented by the equation :

but the only evidence he gives is based on thermal considerations, which show that such a reaction would proceed with development of heat. It is true that if carbonyl sulphide, as ordinarily prepared, is passed through a glass tube heated to redness, much carbon disulphide is present in the escaping gases, but I find that i f the carbonyl sulphide i8 previously purified by passing either through triet hylphosphine or over wood charcoal, no carbon disulphide can be detected in the pro- ducts of decomposition.* I n these experiments, the temperature was varied from about 200' to a bright red heat, and the main reaction was found to be expressed by the equation :

cos = co + 8.

2cos = co, + cs,,

For the purpose of these experiments, the carbonyl sulphide mas prepared by Klason's method (2 pr. Chem., 1887, [ii], 36, 64). A mixture of 290 C.C. of concentrated sulphuric acid with 400 C.C. of water was cooled, 50 C.C. of a solution of potassium thiocyanate satu- rated a t the ordinary temperature were added, and the whole heated to 25' on the water-bath. Carbonyl sulphide is slowly evolved without, any frothing taking place, and can be collected and stored over sul- phuric acid. The impurities invariably present are carbon dioxide, carbon disulphide, and hydrogen sulphide ; hydrogen cyanide is absent if pure potassium thiocyanate is used in the preparation.

The carbon disulphide was removed by ignited wood charcoal, the carbon dioxide by caustic potash,? and the hydrogen sulphide either by means of mercuric oxide or by long standing over sulphuric acid.

When the gas so prepared is mixed with excess of oxygen(2 volumes) in a eudiometer and sparked, a violent explosion takes place and the products are carbon dioxide, sulphur dioxide, sulphur trioxide, and some sulphur.

If the removal of hydrogen sulphide has been made more complete by leaving the gas for 2-3 days in contact with dry mercuric oxide (over mercury), and if the mixture with oxygen is dried for several days over phosphorus pentoxide, an explosion still takes place on sparking, but it is much less violent, and combustion is in no case complete. Even in presence of the excess of oxygen, much sulphur is deposited, and carbon monoxide remains unburnt ; in fact, when the

* Ilosvay (Buli!. Soc. Chim., 1882, [ii], 37, 294) showed that wood charcoal entirely removes carbon disulphide from carbonyl sulphide.

j- A strong solutioii of caustic potash only slowly absorbs carbonyl sulphide, dilute solutions, however, act rspidly,

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COMBINATION OF DRY CARBON MONOXIDE AND OXYGEN. 363

in order to avoid contact with air, was dis- tilled directly into the eudiometers, which were constructed as shown in Fig. 2.

Phosphorus pentoxide, introduced into the i

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364 RUSSELL: INFLUENCE OF THE NASCENT STATE ON THE

over ignited and purified charcoal before treatment with sulphuric acid, and the mercury used in the eudiometer was distilled in a, vacuum.

On sparking these mixtures, explosions usually took place, but in one case the flame died out about half-way down the tube, and in another there was no explosion. The general result obtained on analysing the products showed that

25-40 per cent, was burnt. 25-35 ,, ,, unchanged. 30-40 ,, ,, converted into CO.

It follows from these experiments that, as the quantity of impurity diminishes,

(1) the amount of carbonyl sulphide unburnt increases, (2) the amount of carbon monoxide produced and left unburnt in-

The first of these conclusions indicates that pure carbonyl sulphide will not burn when sparked with oxygen; this point will be further dealt with later. The second gives us the very interesting result that to a great extent carbon monoxide is not attacked by oxygen even when it is freshly produced in the flame of an explosion in presence of an excess, and sometimes a large excess, of oxygen.

I n this reaction, there is probably very little heat developed on the whole. Thermal data as given by different observers vary greatly, but it would appear that the splitting up of citrbonyl sulphide into carbon monoxide and sulphur requires addition of energy, and this would use up the heat derived from the combustion which does take place.

I now proceeded to study the effect of increasing the energy of the reaction by exploding mixtures of carbonyl sulphide, carbon disulphide, and oxygen. These mere made by adding known quantities of the gaseous mixture, CS, + 30,, t o measured volumes of carbonyl sulphide with excess of oxygen. The effect of even a small addition of carbon disulphide is to diminish greatly the amount of carbon monoxide left unburnt. With 4 per cent. of carbon disulphide in the mixture, 9 per cent. of carbon monoxide was found unburnt.

The energy was now increased in a different way, namely, by liberating carbon monoxide by the explosion of nickel carbonyl and oxygen-a reaction known to proceed with great development of heat.

(b) Combustion of Nickel Cmrbony2.-Nickel carbonyl readily reacts with oxygen in the cold, sometimes with violent explosion.* The

* On one occasion, some nickel carbonyl, when introduced into a eudiometer containing oxygen over mercury, caused so violent an explosion that the eudiometer was shattered, and two of us standing near were badly cut.

creases.

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COMBINATION OF DRY CARBON MONOXIDE AND OXYGEN. 365

Nascent CO

experiment was therefore carried out in a eudiometer with two chambers so that the two substances could be dried separately (Fig. 3). The nickel carbonyl was contained in a glass boat. After standing for a few days, the tap was turned so that the vapour of the carbonyl could diffuse into the oxygen ; after an hour, the tap was closed and an electric spark was passed, producing an explosion. Analysis showed that some carbon monoxide escaped combustion, but not more than 3 per cent.

0, ......... 36 per cent. CO, ......... 62 ,, ,, co ......... 2 ,, ,,

The gases contained in the chamber A had the composition :

It is interesting to compare these results with those obiained by Professor Dixon in his experiments on carbon monoxide (Trans., 1896, 69, 784). Slightly impure mixtures of carbon monoxide and excess of oxygen were sparked, a flame travelled down the tube, and on

FIG. 3.

40 per cent. in limit- ing explosioii of COS and oxygen.

analysis i t was found that quantities of carbon monoxide varying up to 50 per cent. remained unburnt. I n another series of experiments, dried mixtures of carbon monoxide and oxygen were fired by means of carbon disulphide, and 13 per cent. of the carbon monoxide escaped combustion. Notwithstanding the fact that in these experiments ordin- ary molecular carbon monoxide was employed, the results are strikingly similar to those I have obtained with nascent carbon monoxide. This similarity is brought out in the following table, which shows the maxi- mum amount of carbon monoxide left unburnt after explosion :

Molecular CO

Reaction accompanied by small heat

evolntion.

50 per cent. in limit- ing explosion of CO and oxygen.

I

Reaction accompanied by greater heat

evolution.

9 per cent. in ex- plosion of COS and oxygen with 4 per cent. CS,.

13 per cent. i n ex- plosion of CO and oxygen with 4 per cent. CS,.

Reaction accompanied by still greater heat

evolution,

3 per cent. in ex- plosion of Ni(CO), and oxygen.

VOL. LXXVII. D D

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366 RUSSELL: INFLUENCE OF THE NASCENT STATE ON THE

The comparison must not be pushed too far ; it is quite impossible to have exactly the same conditions in any two experiments with partially purified substances, but the general results given in the table suggest that :

(1) The energy developed in the reaction has considerable influence in promoting the union of carbon monoxide and oxygen. This result may be simply due to the higher temperature to which the gaseous mixture is raised.

(2) The nascent condition of the carban monoxide has no very great influence,

11. Intermtion of Carbon Monoxide and Nascent Oxggeia. Explosion, of Chlorine Monoxide cmd Carbon Monoxide.

This experiment was suggested during the discussion which fol- lowed the reading of the joint paper of Professor Dixon and myself in 1897. It was urged tha t “nascent ” oxygen obtained in the decom- position of chlorine peroxide (used in the experiments in that paper) was not strictly atomic, and that a better oxide to use would be chlorine monoxide.

This has now been done, although the experimental difficulties proved to be considerable. I find that when dried mixtures of carbon monoxide and excess of chlorine monoxide are sparked, there is a violent explosion, but from 5-10 per cent. of the carbon monoxide remains unburnt. This is a much smaller quantity than was left in the case of the chlorine peroxide explosions (50-70 per cent.); it must, however, be borne in mind that a consider- able amount of oxygen was present in the latter, and the results of the preceding section lead us to expect that the oxygen, by dimi- nishing the intensity of the reaction, would increase the percentage of carbon monoxide unburnt. Another difference between the two cases lies in the fact that the explosion of chlorine monoxide is more violent than tha t of the peroxide, and a third is that in one case the ‘nascent ’ oxygen is strictly atomic whilst in the other it is not.

The preparation of chlorine monoxide is not dangerous if the mate- rials and apparatus are carefully freed from organic matter and no indiarubber connections are used. Chlorine, generated by acting on recrystallised potassium dichromate with pure hydrochloric acid, is passed through water, sulphnrio acid, and two tubes containing anhy- drous copper sulphate on pumice cleaned by treatment with aqua regia, and finally over precipitated mercuric oxide which has previously been dried for six hours at 400”. All parts of the apparatus were sealed together, and the delivery tube ground into the neck of the generating flask (Fig. 4).

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COMBINATION OF DRY CARBON MONOXIDE AND OXYGEN. 367

The mercuric oxide is kept surrounded by ice ; in my experiments it was prepared by adding caustic potash to a hot dilute solution of mer- curic chloride which had been purified by dissolving in alcohol and reprecipitating by addition of water."

Prolonged drying is absolutely essential for the production of chlorine monoxide. If the experiment is properly carried out, chlor- ine is absorbed for about an hour, and then chlorine monoxide is evolved, a fairly large yield being obtained, although the operation is slow. No change in colour is observed in the solid contents of the tube, but as soon as air is admitted the solid darkens. On shaking it into dilute hydrochloric acid, there is a lively effervescence and some metallic mercury separates out ; whatever the reaction between chlor- ine and mercuric oxide may be, it seems to involve something more than the simple formation of either mercuric chloride or mercuric oxychloride.

FIG. 4.

If, however, the mercuric oxide has not been sufficiently dried, it is converted into a white mass and the gas obtained is chiefly oxygen with but little chlorine monoxide.

The chlorine monoxide was condensed in a bulb surrounded by solid carbon dioxide. When a sufficient quantity had collected, the carbon dioxide was removed and the liquid allowed to slowly evaporate. The first portion tha t comes off is chiefly chlorine, later fractions are, however, explosive and finally nearly pure chlorine monoxide is obtained. The liquid is reddish-brown in colour and the gas very closely resembles diluted nitrous fumes. Great care must be exer- cised in collecting samples of the gas ; on one occasion, the sample tube used was not quite free from dust, having been wiped out with a soft duster which left a few specks of cotton on the walls, and imme- diately the gas ca,me.in contact with these there was a violent explo- sion which reached the liquid in the bulb, with the result that the bulb and the beakers surrounding it were completely pulverised. This is, however, the only accident I have had; if dust and organic matter

* This affords a very rapid and easy method of purifying mercuric chloride. D D 2

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368 RUSSELL: INFLUENCE OF THE NASCENT STATE ON THE

are carefully excluded, liquid chlorine monoxide cannot be considered a dangerous body.

Mr. E. B. Le Mare has kindly given me much assistance in the preparation of this substance.

Reaction with Carbon Nmoxide.--In the earlier experiments, mix t urea of the two gases were made in the proper proportion, left to dry over distilled phosphorus pentoxide, and kept in the dark in an ice-chest. On sparking, no explosion took place. The contents of other tubes which had not been sparked were examined, and found to consist of carbon dioxide and chlorine, together with some unchanged carbon mom oxide and chlorine monoxide ; there was no oxygen, and I could detect no carbonyl chloride. A t the end of 4-5 days, there was very little left of either carbon monoxide or chlorine monoxide. It follows then tha t at 0' and in the dark these two substances slowly react according to the equation :

co + C1,O = co, + GI,."

The two gases were therelore dried separately for about 2 days a t 0' and then allowed to diffuse into each other for one hour, the bulb con-

taining the heavier chlorine monoxide being placed so that the gas flowed down into the other. The tap separating the bulbs was then turned off and an electric spark passed in each. Explosions took place and the products were collected and analysed :

(1) Mixture before sparking: 1 vol. UOI-2 vols. C1,O (approxi- mately).

Gases left after explosion and standing over mercury to absorb chlorine :

GO, = 57, 0, = 39, CO = 4 per cent. * This is, I believe, the only instance known of direct oxidation of carbuii

monoxide at low temperatures. Remsen has shown that mixtures of carbon mon- oxide and ozone can be heated to temperatures a t which ozone rapidly deconkposes without forming carbon dioxide. This action can readily be explained if we suppose that carbon monoxide and chlorine monoxide unite, forming an additive compound which readily breaks up into chlorine and carbon dioxide. The unsaturated character of chlorine monoxide, as shown by its direct combination with sulphur, and of carbon monoxide, as shown by its readiness to unite with chlorine, would lead us to expect something of this kind,

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COMBINATION OF DRY CARBON MONOXIDE AND OXYGEN. 369

(2) Mixture before sparking: 1 vol. C O + 2 vols. C1,O (approxi-

Gases after explosion and absorption of chlorine : mately),

CO, = 60, 0, = 35, CO = 5 per cent.

I n each case, about 6 or 7 per cent. of the carbon monoxide originally put in is left unbnrnt, although the drying was far from complete (30 hours only) and the explosion vigorous.

111. Interaction of Ncment Ca!rbon Monoxide with Nuscent Oxygen. This experiment was carried out in a manner precisely similar to

that adopted by Dixon and Russell (Zoc. c i t . ) . Chlorine peroxide and carbonyl sulphide were bubbled separately through sulphuric acid and allowed to mix, they were then passed into a eudiometer containing distilled 'phosphorus pentoxide. Pure chlorine peroxide, obtained by fractional distillation of the liquid, was used instead of the diluted gas. No cork or rubber connections were used in the apparatus, carefully ground-in glass connections being substituted.*

The text-book method of preparing chlorine peroxide, namely, by the action of strong sulphuric acid on potassium chlorate, is dangerous and does not give a pure product. The method I adopted was essentially a modification by Schacherl (Annalen, 2881, 206, 68) of one described by Calvert and Davies (this Journ., 1859, 11, 193), which I have always found to be perfectly safe. 115 grams of recrystallised oxalic acid were dissolved in 200 C.C. of water, the solution cooled, 100 C.C. of strong sulphuric acid added, and the whole allowed to cool so slowly that large crystals were formed.? 25 grams of finely powdered re- crystallised potassium chlorate were added, the mixture well shaken, and heated to 40-50' on the water-bath. The gases evolved-carbon dioxide, chlorine peroxide, and a trace of chlorine (Pebal and Schacherl, AnnuZen, 1882, 213, 113)-were dried by calcium chloride and passed into a receiver cooled by ice and salt where the chlorine peroxide con- denses to a liquid having the colour of potassium dichromate. The liquid is comparatively stable, and I have repeatedly fractionated it without accident. It has, however, exploded under the following condi tioos :

(1 .) Contact with concentrated snlphuric acid. (2.) The mechanical shock occasioned by pouring fresh freezing

The explosions were violent; in one case the bulb was ground to a * The wires must be sealed into the wide part of the eudiometer; explosions

-i- This is important, as when the cooling was rapid and the crystals small, the

mixture on to the containing bulb.

brought about by the spark are not propagated in the narrow tubes at the ends,

mixture frothed very much during the preparation,

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370 RUSSELL: INFLUENCE OF THE NASCENT STATE ON THE

fine powder, a duster wrapped round it torn to shreds, and a stout wooden box on which it was standing shattered.

It is, however, perfectly safe to blow gases, for example, carbon dioxide, through the liquid or to shake it about in a narrow tube (3 mm. diameter),

(1.) By contact with organic matter, such as traces of impurity in sulphuric acid or phosphorus pentoxide.

(2.) By scratching the tube containing it with a file. (3.) By shaking pieces of broken glass in it.

The explosions, however, always stop a t narrow tubes. The gas gradually decomposes over mercury, and is only slowly ab-

sorbed by caustic potash or soda; i t will, in fact, bubble through solutions of these without much loss, and a moistened stick of caustic potash requires to be left for 10-12 hours in contact with the gas to effect complete absorption. Undistilled phosphorus pentoxide is acted upon, giving a red substance; it becomes hot and has even caused an explosion. Pure phosphorus pentoxide, however, is not affected ; the gas can be kept over it for 2-3 days a t 0' without much decomposition.

The mixtures of chlorine peroxide and carbonyl sulphide were allowed to dry for 24 hours in the ice chest and then exploded either by means of a spark or by heating in an air-bath; the gases lost their deep green colour and became colourless. When the explosion was brought, about by sparking, carbonyl chloride could always be detected among the products, its pungent odour being readily recopisable even in presence of chlorine and sulphur dioxide; if the explosion were caused by gradual heating, I could never clearly detect any of the chloride. I n other respects, the results were identical. The amounts of carbon monoxide obtained were :

1 vol. COS+5& or 6 vols. C10, I ,, +4 or 44 ,, about 28-4 per cent. of the

1 ,, + 1 5 (rather less) vola. C10, ,, 20 per cent. of the

These results show that when carbon monoxide and oxygen are brought together, both being in the nascent condition and also heated by the flame of an explosion, combination is not complete. I f longer drying of the chlorine peroxide were possible, no doubt a larger per- centage of uncombined carbon monoxide would be found.

The gas has been caused to explode :

No CO found

COS is left as CO

COS is left as CO

IT. Inertness of prre Capbonyl XuZphide towards Oxygen.

W e have already seen that the further the purification of carbonyl sulphide is carried, the greater is the proportion left unburnt when

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COMBINATION OF DRY CARBON MONOXIDE AND OXYGEN. 371

mixtures of carbonyl sulphide with excess of oxygen are sparked. This can only be interpreted as showing that pure carbonyl sulphide will not explode on sparking with oxygen. So far, only one such sample has been obtained, and I have not found any method of purification which can be relied upon to give a sufiiciently pure gas. In mixtures of carbonyl sulphide and nitrous oxide (which explode if not purified), after standing fo r some weeks over pure sulphuric acid, and for a further lengthy period over phosphorus pentoxide, an electric spark produces no explosion, On now decanting the gaseous mixture into another eudiometer, adding a drop of water, and passing a spark, a violent explosion takes place.

Conclusions.

The conclusions to be drawn from the above experiments are : 1. Pure carbonyl sulphide will not explode if sparked with oxygen. 2. If a small quantity of impurity is present, a flame traverses

the whole tube on sparking the mixture, but combustion is not nearly complete ; part of the carbonyl sulphide remains unburnt, and part is decomposed into carbon monoxide and sulphur, which likewise do not burn,although excess of oxygen and a small quantity of impurity are present. As, however, this quantity increases, com- bustion rapidly becomes more complete.

3. Mixtures of carbonyl sulphide and nitrous oxide require a larger quantity of impurity to cause combustion than mixtures of carbonyl sulphide and oxygen in the same circumstances. It seems probable that the quantity necessary for the latter mixture is also different from that required by mixtures of carbon monoxide and oxygen.

4. The state of a.ffairs following on a violent reaction-such as ex- plosion of carbon disulphide or chlorine monoxide, &c., has a very con- sid erable influence in bringing about combination of carbon monoxide and oxygen. Whether this is a direct effect, or due to a heightening of the action of the “third substance,” there is as yet little evidence. I can find no evidence that the nascent state, per se, is very effective. When the conditions were made as nearly as could be the same, there did not seem to be a great difference between the behaviour of nascent carbon monoxide and that of molecular carbon monoxide as studied by Dixon.

Finally, I wish to thank Professor Dixon for much kindly help and advice given during the progress of this research.

THE OWENS COLLEGE, MANCHESTER.

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