COLLOIDAL SUSPENSIONS I N NON-AQUEOUS SOLVENTS
21
CHEMICAL PREPARATION O F COLLOIDAL SUSPENSIONS I S NON-AQUEOUS SOLVEXTS. I1
ETHER,DIOXANE,AND ACETONE ARTHUR A. VERNON'
AND
HARRISON A. SELSON*
Department of Chemistry, Rhode Island State College, Kingston, Rhode Island Received April 1 1 , 1099
In a previous paper the authors (1) have described the preparation and properties of some inorganic colloids in methyl alcohol and benzene. This paper gives the results of similar experiments with diethyl ether, 1,4dioxane, and acetone as the solvents. EXPERIMENTAL
Materials All materials used were of C.P. grade. The solvents, diethyl ether, 1,4-dioxane, and acetone, were redistilled before use.
Procedure The methods by which the colloids were prepared were the same as those reported in the previous paper. The observations there made about the use of reducing agents and of hydrogen sulfide were found to apply equally well to ether, dioxane, and acetone as solvents. The protective agents used were collodion for acetone and dioxane and rubber for ether. These were used in the same way as described previously. RESULTS
The results of the investigation are shown in tables 1, 2, 3 and 4,which list the stable metal and metallic sulfide sols prepared. The more significant results of the experiments are set forth below, classified under the dispersion medium and dispersed phase. 1. Ether as dispersion medium
Stable gold sols were easily prepared with phosphorus, hydrazine hydrate, and stannous chloride in the presence of rubber. Without protective colloids, purple or blue sols of 30 to 60 min. stability were formed with the same reducing agents. ( b ) SiZver: Salts of silver are insoluble in ether, and sols were therefore impossible in the pure solvent. Addition of a very small amount of (a) Gold:
1 Present address: Department of Chemistry, Kortheastern University, Boston, Massachusetts. * Present address: Department of Chemistry, The Rice Institute, Houston, Texas.
22
ARTHUR A. VERNON AND HARRISON A. NELSON
an alcohol solution of silver nitrate produced a sufficient concentra.tion to give a sol when reduced, but the dispersion medium could no longer be considered pure ether. (c) Other elements: With the exception of bismuth, tin, and iron, other metals presented a problem similar to that met in silver. Although some TABLE 1 Metallic sols i n ether ( w i t h protective colloid) COLOR
DIS PEBBED PEA~E
B y transmitted
Au... . Au.. . , Bi... . , Sn. . . . Fe. , , . . Pb. . ..
light
B y reflected light
Rose Rose Red-brown Yellow Green-yellow Yellow
Tan Tan Brown-gray Green Dark-gray green Green-yellow
i
BEDUCINQ AQENT
Hydrazine Phosphorus Phosphorus-h ydraeine Phosphorus-hydrazine Phosphorus-hydrazine Phosphorus-hydrazine
METALLIC SALT REDUCED
AuCla AuCla SnCl? FeCla Pb(CzHaOz)z
TABLE 2 Metallic sols in dioxane ( w i t h protective colloid) DIB-
:?EY Au . . . . Au . . . . Au . . . . F e . ,. . . Sb. . .. Ag. . . . Pb . . . . Bi.. . . . Ni, . .. Co. . .. H g . ., . Cu . . . .
j
1
COLOR REDUCINQ AQENT
B y transmitted
light
B y reflected light
Purple-red Purple Purple-blue Red Yellow Light yellow Red-brown Red-brown Yellow Amber Tan Red-brown
Brown Brown Brown Brown Yellow Gray Brown-gray Brown Gray Tan Dark gray Tan-gray
METALLIC BALT REDUCED
Hydrazine Stannous chloride Excess hydrazine Phosphorus-hydrazine Phosphorus-h ydrazine Hydrazine Phosphorus-hydrazine Phosphorus-h ydrazine Phosphorus-hydrazine Phosphorus-hydrazine Phosphorus-hydrazine Phosphorus-hydrazine
salts were slightly soluble, none of those used was capable of producing sols on reduction. 2. Dioxane a s dispersion medium
(a) Gold: A blue sol was formed by reducing auric chloride in dioxane without a protective colloid. Precipitation was complete in one minute. Stannous chloride reduced auric chloride to a deep blue sol in the presence of cellulose nitrate, the color changing to light purple on long standing.
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COLLOIDAL SUSPENSIONS I N NON-AQUEOUS SOLVENTS
Phosphorus-hydrazine gave a definite green sol with auric chloride, stable for several months. TABLE 3
Metallic sols in acetone (with protective colloid) DIG PERSED
Au Ag Ag Bi Ni
j ~
-
COLOR
By
trF$Ftted
Amber Yellow Red-brown Yellow Red-brown
METALLIC SALT REDUCED
REDWCINQ AQENT
~
By reflected light
i
Tan Yellow-gray Black Yellow-green Black
Phosphorus-hydrazine Hydrazine Phosphorus Phosphorus-bydrazine Phosphorus-hydrazine
AuCla AgNOa AgNOa BiONOa Ni(NOa)?
TABLE 4
Stable metallic sulfide sols in ether, dioxane, and acetone ( w i t h protective colloid)
i FIDE ~
I Pb Bi
..I
Xi Co
Color by reflected light
Cu
I N DIOXANE
'
I N ACETONE
Color by reflected light
Color by transmitted light
Color by refleoted light
Brown
Gray
Light brown Brown
Gray
AgNOa
Black
Pb(N0aL
Gray Light brown Orange Black Black Black
Amber Light brown
Yellow Gray
Amber
Yellow
Red-brown Brown
Bi(N0a)s
Red Gray Gray Brown
Orange Black Black Black
SbCls HgNOa Ni(K0s)t CO(KOS)2
Green
Gray
SnCl? FeCL
Yellow Orange
Green Yellow
cue12 AsCla CdCl,
Amber Gray . 1 Orang1 Yellow
Cd. . /
SALT U S E D
Color b y tranamrtted light
Light brown Light brown Orange Red Gray Black Black Black Black Brown
Gray Graybrow1 Amber Olive
Sn Fe
AS
INETHER
Color by transmitted light
~
( b ) Silver: Silver oxide was used in dioxane, as silver nitrate is insoluble in this solvent. Silver oxide was reduced to stable sols with most reducing agents. ( c ) Lead: Lead salts were reduced by phosphorus-hydrazine alone in dioxane. Lead acetate was reduced to a very stable sol, while lead nitrate was reduced to unstable sols.
24
ARTHUR A. VERNON AND HARRISON A. NELSON
( d ) Nickel and cobalt: Nickel and cobalt nitrates were reduced by phosphorus-hydrazine to stable sols, v7hile their chlorides formed unstable sols. A small amount of cobaltous sulfate solution or a small amount of a gold nuclear solution added to cobaltous nitrate solution before reduction guaranteed stability. ( e ) Copper: Copper chloride was reduced to a stable sol by phosphorushydrazine, but the nitrate formed unstable sols. (j) Chromium: Chromium salts were reduced by phosphorus-hydrazine, but precipitation was immediate. 3. Acetone as dispersion medium (a) Gold: Reduction by hydrazine in acetone solution was impaired
by the reaction between acetone and hydrazine. Auric chloride was reduced to a blue or purple suspension with hydrazine hydrate in the presence of cellulose nitrate, but on standing the sol reverted to a clear yellow solution, evidently auric chloride, which again formed a blue sol on addition of hydrazine hydrate. The sol disappeared for a second time and further addition of hydrazine hydrate failed to bring it back. Stannous chloride added to auric chloride solution produced a tan colored sol, evidently not of metallic gold. Other reducing agents were ineffective with auric chloride. ( b ) Silver: Silver nitrate was reduced to a stable sol by phosphorus. Hydrazine hydrate had an effect similar to that observed with auric chloride, except that on the third addition of the reagent a stable sol was formed. (c) Lead: Lead acetate solution reduced with phosphorus-hydrazine was cloudy, and precipitated in 8 hr. Lead nitrate reduced with an excess of phosphorus followed by hydrazine produced a lead sol stable for several weeks. ( d ) Antimony: Reduction of antimony trichloride by phosphorushydrazine gave a white flocculent precipitate. (e) Nickel: Nickel nitrate solution reacted with hydrazine hydrate in the same manner as silver. Three separate reductions were necessary to produce a stable sol. (f) Chromium: Chromic nitrate dissolved in acetone and was apparently partially reduced by the solvent, producing a cloudy sol, which precipitated in a short time. DISCUSSION
The general characteristics of sols in methyl alcohol and benzene as given in the previous paper were found to apply equally well to ether, dioxane, and acetone. A comparison of the results of experiments with the five solvents showed that the stability of the suspensions decreased in
VISCOSITY O F SOLUTIONS
25
the order alcohol, dioxane, benzene, ether, and acetone. The general problem of stability of sols in non-aqueous media appears to be very interesting and should merit further investigation. It is hoped that more work may be done in this laboratory to determine changes and precipitation characteristics. SUMMARY
1. Suspensions of several metals in ether, dioxane, and acetone have been prepared by reduction methods. 2. Colloidal suspensions of metallic sulfides in the same solvents have been prepared by double decomposition reaction with hydrogen sulfide. 3. As reported in previous work on methyl alcohol and benzene, protective materials were necessary to ensure stability. Cellulose nitrate was used with dioxane and acetone, while rubber was the best agent with ether. 4. A comparison with results published in a previous paper shows that the suspensions decrease in stability in the order alcohol, dioxane, benzene, ether, acetone. REFERENCE (1) VERNON,ARTHUR.4.,AND NELSON,HARRISON A , : J. Phys. Chem. 44, 12 (1940).
T H E INFLUEKCE OF BROWNIAN MOVEMEKT ON T H E VISCOSITY OF SOLUTIOPTS'
R. SIMHA Department of Chemistry, Columbia L'niversity, New York c i t y , New Y O T ~ Received M a y 1.9, 1999 INTRODUCTION
The study of the internal friction of pure liquids is of great technical as well as scientific interest. From the latter point of view it has become especially important, since a more intensive study of the liquid state has been undertaken. The viscosity and its dependence on other quantities have been shown to furnish substantial information about the structure of the medium considered. No less important is the study of the viscosity of solutions, especially in the study of the high polymers. Besides technical problems this Presented a t the Ninety-seventh Meeting of the American Chemical Society, held a t Baltimore, Maryland, April, 1939.
