Historic, Archive Document

Do not assume content reflects current scientific knowledge, policies, or practices.

The Virginia

Journal of Science

Vol. Ill

MAY, 1943

No. 7



Introduction Fourth Symposium on Organic Analytical Reagents

John H. Yoe . 277

A Progress Report on Organic Analytical Reagent Studies

W. J. Frierson . 279

Organic Reagents Used in the Determination of Iron

William E. Trout, Jr. . 281

A Note on 8-Mercaptoquinoline J. R. Taylor . . 289

.Some Substituted Phenolsulfonephthaleins J. R. Taylor, R. S. Rosen-


Reactivities of Certain Organic Compounds with Inorganic Ions

F. H. Fish, P. J. Walkauskas and M. Fox . 292

Progress Report on Inorganic Analysis with Organic Reagents

E. Louise Wallace and Alfred R. Armstrong . 292

Organic Solvents and Wash Liquids in Analytical Chemistry

Landon Arndale Sarver . 293

Anti-Dianisalacetoneoximehydroxylamine as a New Organic Reagent for the Gravimetric Determination of Tungstates A. Letcher

Jones and John H. Yoe . 301

Sodium Catechol Disfulfonate as a New Colorimetric Reagent for Iron

A. Letcher Jones and John H. Yoe . 301

Spectrophotometric Studies of Some Complex Copper Compounds

James W. Cole, M. Brooks Shreaves and James E. Bowden .... 302 Organic Analytical Reagent Studies: New Colorimetric Reagents for Silver, Copper, Cobalt, Zirconium, and Phenothiazine John

H. Yoe and Lyle G. Overholser . 304

Reactivity of Substituted Thioureas Lyle G. Overholser and

John H. Yoe . 306

Published by The Virginia Academy of Science Monthly, except June, July, August and September


Lexington, Virginia.

The Virginia Journal of Science

Official journal of the


Marcellus H. Stow, President, State Teachers College, Farmville, Va.

E. C. L, Miller, Secretary-Treasurer, Medical College of Virginia, Rich¬ mond, Va.

Sidney S. Negus, Assistant Secretary-Treasurer, Medical College of Vir¬ ginia, Richmond, Va.




Preston Edwards . 1943

John H. Yoe . 1944

H. H. Zimmerley . 1945

H. B. Haag . 1946

Arthur Bevan . 1947


Ruskin S. Freer . 1943

Wortley F. Rudd . 1944

George W. Jeffers . 1945

Marcellus H. Stow . 1946

W. Catesby Jones . 1947


Editor-in-Chief Ruskin S. Freer, Lynchburg College, Lynchburg, Va.

Managing Editor Lt.-Col. Robert P. Carroll, Virginia Military Institute, Lexington, Va.

T. McN. Simpson, Jr. Astronomy, Mathematics and Physics

F. S. Orcutt Bacteriology

Robert F. Smart Biology

J. Stanton Pierce Chemistry

John Alex. Rorer Education

J. H. Rushton Engineering

Chapin Jones Forestry

Edward C. H. Lammers Geology

Carl C. Speidel Medicine

R. S. Henneman Psychology

Entered as second-class matter February 20, 1940, at the post office at Lexington, Virginia, under the Act of March 3, 1879. Subscription $1.00 per volume to members of the Virginia Academy of Science; $2.00 per vol¬ ume to others. Published at Lexington, Virginia.

The Virginia Journal of Science

Vol. Ill MAY, 1943 No. 7

Virginia Academy of Science Roanoke, Virginia May 7-9, 1942

Fourth Symposium on Organic Analytical Reagents


John H. Yoe

This afternoon is the fourth anniversary of our symposium which has been held on the occasion of the annual meeting of the Virginia Academy of Science and which has formed a part of the Chemistry Section programs. In spite of increased duties imposed upon various members of our group, incident to the nat¬ ional emergency, it is encouraging to report that very definite progress has been made during the past twelve months. May I take this occasion to express my regret that it has not been pos¬ sible for me to visit the cooperating institutions during the past year as often as I should have liked ; in fact, several have not been visited at all, though I hope to do so within the near future. This failure on my part you will understand I am sure, has not been through a lack of interest but on account of the fact that the major part of my time has been devoted to war work.

To date more than 5000 organic compounds have been in¬ vestigated by the ten cooperating institutions; about 2700 of these were studied by the group at the University of Virginia; the others were investigated at our sister institutions. The compounds represent a great variety of substances from the standpoint of molecular structure and their study is leading to a better knowledge of the relationships between the structure of organic molecules and their reactivity as analytical reagents. Such studies open the way to the discovery of new specific and highly sensitive organic reagents in inorganic analysis. Today, more than ever before, demands are being made upon the analyst for “trace” analyses. Minute amounts of many constituents that were seldom determined a decade or two ago, are now often de-


termined with a high degree of accuracy as a matter of routine necessity.

Approximately 250 compounds have been investigated at the University of Virginia during the past twelve months. As in pre¬ vious years, the reactions observed were mostly the result of oxi¬ dation of the organic compounds by ions having relatively high oxidation-reduction potentials, such as Ce+4, Au+3, Ir+4, Fe+3, etc. Few of the reactions appear to be valuable in chemical analysis. Two, however, may be mentioned that might find use¬ ful applications: Sodium-1, 8-dihydroxynaphthalene-3, 6-disul¬ fonate and tetradecylbetaine. The former gives a deep red col¬ ored solution with Ti+4 in acid medium; the latter precipitates gold, platinum and iridium.

Work on 2-thio-5-keto-4-carbethoxy-l, 3-dihydropyrimidine as a silver reagent has been completed. The study of the reactions of substituted thioureas has also been finished. Further work was done on the reactions of 5-chlorobromamine acid with zircon¬ ium and on the reaction of 2,4-diacetoxybenzonitril with copper. Spectrophotometric measurements will be made of the latter re¬ action.

The reaction of phenothiazine with palladous chloride has been studied in considerable detail. The complex formed was isolated and the reaction has been used as a basis for the col¬ orimetric determination of small amounts of phenothiazine.

A spectrophotometric study of the reaction of nitrosoresorcinol with cobalt has been made, including the effect of pH, salt con¬ centration, interfering ions, etc. Procedures have been developed for determining cobalt in the presence of iron and nickel.

We regret that it has not been possible for several of the co¬ operating institutions to be represented on our program this afternoon. We acknowledge with thanks the contribution to our symposium by Dr. Landon A. Sarver, American Viscose Corpora¬ tion. Papers and progress reports will now be presented by representatives from: Hampden-Sydney College, Mary Baldwin College, Washington and Lee University, Virginia Polytechnic Institute, College of William and Mary, and the University of Virginia.

University of Virginia.



A Progress Report on Organic Analytical Reagent Studies

W. J. Frierson


In 1939 Malowan1 reported a new method for the detection of gold by the use of morpholine. He reported the test sensitive to 1 part in 50,000 and that copper and iron do not interfere be¬ cause they are precipitated from the solution by morpholine. The gold first gives a yellow color but this gradually changes to a blue-violet.

Among the organic compounds recently investigated, It was found that 4-amino-3-methylphenyl morpholine,

0 (C'Ho.CH,) 0N.CeH4.NH0.CH3 (4,3)

gives a test for gold which is sensitive to 1 part in 30,000,000. The reagent produces a pink color with gold and reacts with sev¬ eral other ions; chromium, vanadium, osmium and europium, pink color; copper, purple color; platinum, brown precipitate; sil¬ ver, purple precipitate ; and ferric iron, purple color. Silver reacts only in neutral solution; the other ions give best results at pH 3 to 5.

Because this seems to be a promising reagent for the detec¬ tion and determination of gold, a detailed investigation has been started.

Solubility of the Reagent

Solvents examined were water, acetone, alcohol, and several mixtures of alcohol and water. The reagent is only slightly soluble in water, a few milligrams per ml. at 25 C. In acetone, 95% alcohol, 50% alcohol and 25% alcohol the compound is very soluble, giving deep reddish-brown solutions. The solutions seem to be stable, no change being noted on standing several months. A 0.2 per cent solution in 50% alcohol was used for the tests. The standard gold solution contained 0.9 mg of gold per ml. and more dilute solutions were prepared by dilution.

Effect of Acidity on the Reagent

Tests were made at pH values from 2 to 11 using a solution of gold containing 1 part in 10,000,000. A good color is formed over the pH range 1 to 5, the optimum being pH 2.5 to 3.0. Above pH 7 no satisfactory results were obtained.


Stability of Color

The pink color seems fairly stable when formed from a solu¬ tion of gold at a concentration of 1 part per million. On stand¬ ing six days the color fades slightly and takes on a purple hue. In more dilute solutions the color may fade within a few minutes. The stability of the color seems to depend to some extent on the pH of the solution but only a few preliminary tests have been made.


1. Malowan, L. S., Z. anal. Chem. 118, 100 (1939).

Hampden-Sydney College.


Organic Reagents Used in the Determination of Iron

William E. Trout, Jr.

Those of us who have had even a small part in the cooperative research program directed by Professor Yoe will recall the high frequency with which organic compounds produce colors or pre¬ cipitates with iron. The literature records well over a hundred organic compounds employed in some manner in the determina¬ tion of iron. The accompanying table indicates the relative dis¬ tribution of some of these compounds among the classes sug¬ gested by Yoe and Sarver in their recent book on Organic An¬ alytical Reagents (1). The names and line formulas of the com¬ pounds are given and also, for some of the salinogenic reagents, the sensitivities expressed as the ratio of parts of iron to parts of solvent.

Of the solvents listed (I), the first seven have been used to extract and intensify the colored compounds formed in colori¬ metric analyses. w-Amyl alcohol, for example, is thus used in the salicylic acid method for the determination of ferric iron. The last three solvents have been used to extract ferric chloride from its aqueous solutions containing hydrochloric acid.

No attempt has been made to complete the lists of compounds in the first five classes, and no reagents for iron are recorded in Yoe and Sarver’s Classes VI, IX, and X.

Our principal interest here is in the salinogenic compounds of Classes VII and VIII.

In the first group of phenolic substances (VII-A-b), at least one hydroxyl is present, and in the compounds listed there is a nearby oxygen atom, either in a hydroxyl group, an ether ling- age, or a carbonyl group, through which chelation might take place. In chromotropic acid the hydroxyls are in the 1,8 positions in the napthalene nucleus.

Not listed here are meta-bromophenol and alpha-naphthol tri- sulfonic acid, reported by J. R. Taylor (2) at our Symposium last spring. Kojic acid (2-hydroxymethel-5-hydroxy-l,4-pyrone) has also been proposed as a colorimetric reagent for iron (3). Of special interest in this group is the sodium salt of pyrocatechol- 3,5-disulfonic acid, announced last spring as a reagent for iron, about which a further report will be made this afternoon by J. H. Yoe and A. L. Jones.

The second group of compounds (b') presumably from chelate rings in which the hydrogen of the hydroxyl is replaced by the metal ion and the ring is closed through the ring nitrogen. 8-Hydroxyquinoline forms an insoluble ferric compound of this nature which is used in a gravimetric procedure. This precipi¬ tate may be centrifuged and dissolved in 95 per cent alcohol, con-


taining a little sodium hydroxide, to form a dark green solution suitable for colormetric determination.

Of these reagents, f err on, first used by Yoe, is perhaps the best known to the Symposium group of chemists and needs no further discussion. Snell (U) states that “This reagent has probably been reported in more detail as to possible interference by other ions than any other one”. The intense green color is specific for ferric ions, and is very sensitive.

Alloxan and alloxantin may not belong in this class, for, al¬ though they contain enolizing groups, there is a possibility that the intense blue compounds formed may result from coordination through two ring nitrogens, as in the 2,2'-dipyridyl complex.

The lake-forming dyestuffs, which are generally used to in¬ crease the visibility of small amounts of insoluble hydroxides such as ferric hydroxide, are usually regarded as adsorbed on the hydroxide. It is also probable that these dyes may form salts of the metals.

Acetylacetone enolizes to form a mono- or dihydroxy com¬ pound (probably the former) which produces an intense red color with ferric ion suitable for colorimetric analysis.

Dimethyl glyoxime produces a sensitive red color with fer¬ rous compounds that may be used in colorimetry.

Both salicylaldoxime and resorcylaldoxime may be used in colorimetric analysis.

The well-known cupferron and the corresponding naphthyl compound, neocupferron, precipitate ferric iron from acid solu¬ tion making possible some otherwise difficult separations.

The relatively long list of isonitroso and related compounds under i form intense colors (usually blues) with ferrous ions; some of them are highly sensitive reagents for the detection of iron. Di-isonitrosoacetone forms an intense blue color in aqueous solution. Isonitrosoacetophenone is used in chloroform solution ; the chloroform dissolves the blue ferrous complex and intensifies the color, providing a very sensitive test.

Sarver has suggested the use of 2-nitroso-l-naphthol-4-sulfonic acid as a very sensitive colorimetric reagent for iron.

Among the hydroxy-carboxylic acids, salicylic, sulfosalicylic, and beta-resorcylic acids are related compounds which produce colors with ferric ions suitable for colorimetry. Salicylic acid has been used for many years, and has been given considerable study. Protocatechuic acid has been studied recently as a colori¬ metric reagent for iron (5). Sulfosalicylic acid produces a yellow color with both ferrous and ferric ions in ammoniacal solution and a red color with ferric iron in slightly acid solution, permit¬ ting the determination of both ferrous and ferric ion concentra¬ tions with the same reagent. Unfortunately, it is necessary to wait four hours for the development of the colors (8, 9, 10).


o-Quinaldic acid, with a carboxyl group ortho to the ring nitro¬ gen of quinoline, produces a red color with ferric ions suitable for use in colorimetry.

The arsonic and sulfinic acids listed in the next groups form insoluble ferric salts suitable for use in gravimetric analysis. _

Among the thio compounds, thiogly colic acid (mercaptoacetie acid) has been given careful study as a reagent for use in color¬ imetry. This acid has been used for the determination of iron in milk, blood, urine, feces, etc. The reagent reduces the ferric blue-purple to the ferrous red-purple, but the ferric color may be restored by shaking in air, even after 24 hours.

The imino compounds listed produce colors with iron.

Alloxan and alloxantin are here classified (VH-C-b) in ac¬ cordance with the possible functional groups.

The amino compounds of Class VIII form colors, precipitates, or microcrystals with iron, for which analytical applications have been suggested.

Among the nitrogen ring compounds, alloxan, alloxantin, and antipyrine are again classified as previously indicated, because of the possibility of their action with iron through their ring nitrogen atoms.

2,2'-Dipyridyi, 2,2'-phenanthroline, 2-pyridylhydrazine, and the remaining compounds, with the exception of quinoline, pro¬ duce colors with ferrous iron. Note that each of them contains two nitrogen atoms in different rings.

2,2'-Dipyridl is a useful reagent for the colorimetrc determi¬ nation of ferrous iron. It is sensitive and specific, with relatively few interfering ions. It has been used to distinguish hematin and non-hematin iron in yeast, and to determine iron in egg- yolk, grains, etc.

2,2'-Phenanthroline and pyramidone have been used as col¬ orimetric reagents for iron.

Excluding the colorimetric methods utilizing thiocyanate, ferrocyanide, ferricyanide, sulfide, and chloride of iron, there are listed in Yoe’s Photometric Chemical Analysis, Vol. I (Col¬ orimetry) (6), published in 1928, three organic colorimetric re¬ agents for iron; namely, salicylic acid, dimethyl glyoxime, and acetylacetone. Snell and Snell, in Colorimetric Methods of An¬ alysis (U), published in 1986, described the use of twelve organic colorimetric reagents for iron. Several have been added to the list during the intervening years. Although some of these re¬ agents have proved their usefulness under proper conditions, much more detailed study appears to be warranted in many cases, and we feel safe in saying that the ideal colorimetric re¬ agent for iron is yet to be found.

Among the great number of organic compounds available or


yet to be synthesized, we may confidently expect to find many more that will be useful in the determination of iron.

An extensive bibliography is not necessary here, since ex¬ haustive references to these compounds may be conveniently ob¬ tained from Yoe and Sarver’s Organic Analytical Reagents. (1).

Table of Organic Reagents Used in the Determination of Iron

(According to Yoe and Sarver’s Classification)

I. Solvents and Wash Liquids

Carbon disulfide Chloroform Carbon tetrachloride w-Amyl alcohol Ethyleneglycol monomethyl ether

Ethyleneglycol mono-w-butyl ether

Ethyl ether Isopropyl ether Dichloroethyl ether










II. Organic Acids and Bases Used in Neutralization and Control of pH

Acetic acid CH3COOH

Benzoic acid C6H5COOH

Succinic acid (CH2COOH)2

Hexamethylenetetramine (CH2)6N4

III. Organic Oxiding Agents

Methylene Blue Ci6H18N3SC1

IV. Organic Reducing Agents

p-Phenetidine NH2.C6H4.OC2H5

p-Phenylenediamine NH2.C6H4.NH2

2.5- Bis;-(2,4-dimethyl-A^)yrryl)

3.6- dibromohydroquinone C6Br2 (OH) 2 (C H3C4H2N.CH3) 3

V. Indicators

Alizarin CfiH4(CO)2C6H2 (OH)2

Alizarin Red S C6H4(C0)2C6H(0H)2S03H


VII. Acid Salinogenic Compounds

A. Acidity due to alcoholic


b. Phenolic substances

Chromotropic acid 2,4-Dihydroxyacetophenone Gallic acid Pyrocatechol

Pyrocatechol-3,5-disulfonic acid, sodium salt


Pyrogallol dimethyl ether

(HO)2.C10H4.(SO3H)2 CH3.CO.C6H3. (OH) 21 :1, 000,000 (OH)8.C6H2.COOH CgH4.(OH)2

(OH) 2.C6H2. (S03Na) 2 1 :75,000,000 CgH3.(OH)3 (OH).C6H3.(OCH3)2

b'. Phenolic hydroxyl and nitrogen ring




8-Hydroxyquinoline (Oxine) 5-bromo derivative 5-chloro derivative 5,7-dibromo derivative 7-iodo derivative 7-iodo-5-sulfonic acid derivative (Ferron)

c. Lake-forming

Alizarin Alizarin Red S Hematin Hematoxylin

d. Enolizable kei Acetylacetone

CO : (NH.CO.)2:CO Semiquinone of alloxan and tartronyl urea 1:1,000,000 C6H5.C3HON2:(CH3)2 C9H6N.OH HO.C9H5N.Br HO.C9H5N.Cl HO.C9H4N.Br2 HO.C9H5N.I

HO.C9H4N.(I) (S03H)




cgh4 (co) 2c6h (oh) 2so3h



ones and diketones

CH3CO.CH2.CO.CH3 1 :17,000

e. Alpha-Dioximes

Dimethyl glyoxime CH3.C ( :NOH) .C ( :NOH) .CH3


Glyoxime CH ( :NOH) .CH ( :NOH)

g. o-Hydroxyomines

Resorcylaldoxime (OH) 2.C6H3.CH ( :NOH)

Salicylaldoxime OH.C6H4.CH ( :NOH)


h. Other oximes






i. Nitroso and isonitroso compounds


2,4-Dinitrosoresorcinol Isonitrosoacetoacetic acid esters

Isonitrosoacetone Isonitrosoacetone dicarboxylic acid esters

Isonitrosoacetone methyl ether Isonitrosoacetophenone

Isonitrosoacetylacetone Isonitrosobenzalacetone Isonitrosobenzoylacetone Isonitrosobromoacetoacetic acid esters


Isonitrosocyanacetamide Isonitrosocyanacetylurea Isonitrosodibromoacetoacetic acid esters

2-Isonitroso-l-ketotetralin 1 -N itr oso-2-naphthol 2-Nitroso-l-naphthol-4- sulfonic acid


HON rCH.CO.CH :NOH 1:10,000,000 (NO)2.C6H2.(OH)2 CH3.CO.C ( :NOH) .COOR


ROOC.CHo.CO.C ( :NOH) .COOR CHb.CO.CH :NO.CH3 C6H5.CO.CH:NOH 3:100,000,000 CH3.CO.C(:NOH).CO.CH3 C6H5CH :CH.CO.CH :NOH C6H5.CO.C ( :NOH) .CO.CH3



CHBr2.CO.C. ( :NOH) .COOR CioH80 ( :NOH)




NO.C10H4(OH) (S03Na)2

k. Hydroxy-carboxylic acids

Citric acid

Protocatechuic acid Beta-Resorcylic acid Salicylic acid Sulfosalicylic acid Tannic acid Tartaric acid

HOOC.CH (OH) .CH (OH) COOH CH2COOH (OH)2.C6H3.COOH (OH)2.C6H3.COOH 1:20,000,000 OH.C6H4.COOH 4 :10,000,000 0H.C6H3(C00H).S03H



m. Amino -carboxylic acids

Cysteine HS.CHo.CH (NH2) .COOH

o-Quinaldic acid C9HGN.COOH

n. Arsinic and arsonic acids

p-w-Butylphenylarsonic acid C4H9.C0H4.AsO (OH) 2 0. Sulfonic and sulfuric acids

Benzensulfinic acid (7) C6H5.S02H

Naphthalene-l-sudfinic acid CioH7.S02H

Naphthalene-l-sulfinic acid Ci„HT.S02H

B. Mercapto group

Diethyldithiocarbamic acid (sodium salt)

Dithiooxalic acid (potassium salt) Dithiooxamide 5-Mercapto-3-phenyl-2-thio- l,3,4-thiodiazol-2-one Thioglycolic acid Thiocarbonic acid

(CoH5) o.N.CS.SNa

(COSK)o (NH :C.SH)2




C. Active imino group a. Imino group present






(CoH5.NH.NH)2.CO Ci0H7NH.NH.CO.N :N.C10Ht CioH7NH.NH.CO.N :N.C]0H7 C0H5.NH.NH. CO. N :N.CoH5 CoH5.NH.NH.CO.NH,CgH5

b. Substances containing enolizable imino groups

Alloxan CO : (NH.CO.) 2 :CO

Alloxantin Semiquinone of alloxan

and tartronyl urea

VIII. Basic Salinogenic Compounds

A. Amines,, amides, and substituted



1- Naphthylamine

2- N aphthylamine m-Phenylenediamine Triethanolamine







B. Nitrogen ring compounds







2-Methyl pyridine




2-Pyridylhydrazine 2- (2'-Pyr idyl) -pyrrole 2- (2'-Pyridyl) -quinoline Quinoline

2- (2'-Quinolyl) -quinoline 2,2',2'-Tripyridyl

XL Alkaloids


CO : (NH.CO)2:CO Semiquinone of alloxan and tartronyl urea CGH5.C3HON2:(CH3)2 C5H4N)2 1:1,600,000




(CH3) oN. (CH3) 2.C3N2O.C6H5 5:100,000 CcH5N

c5h4n.nh.nh2 . c5h4n.c4h3nh c5h4n.c9h6n c9h7n


(C5H4N)3 l MataraS Products






C21 Hoo OoNo



CO.OCHo.O.C. ( CHo.COONa) 2


1. Yoe, J. H., and Sarver, L. A., Organic Analytical Reagents. John Wiley and Sons, New York, 19 Ul.

2. Taylor, J. R., Virginia Journal of Science, 3, 24 (1941).

3. Moss, M. L., and Mellon, M. G., Ind. Eng. Chem., Anal. Ed. 13, 612 (1941).

4. Snell, F. D., and Snell, C. T., Colorimetric Methods of Analysis. D. van Nostrand Company, New York, 1936.

5. Pereira, R. S., J. Biol. Chem. 137, 417 (1941).

6. Yoe, J. H., Photometric Chemical Analysis, Vol. I, Colorimetry. John Wiley and Sons, New York, 1928.

7. Thomas J., J. Chem. Soc. 95, 344 (1909).

8. Alten, F., Weiland, W., and Hille, E., Z. anorg. allgem. Chem. 215, 81 (1933).

9. Lapin, L. N., and Kill, W. E., Z. Hyg. Infektionkrankh. 112, 719 (1931).

10. Lorber, L., Biochem. Z. 131, 391 (1927).

Mary Baldwin College


A Note on 8-Mercaptoquinoline

J. R. Taylor

The sulfur analog (1) of 8-hydroxyquinoline (II), oxine, was prepared in this Laboratory for comparison of its analytical activity with that of the hydroxy compound.



' I


(I) Me(rcaptoquinoline

l l \A/

(II) Hydroxyquinoline

s s



III \/\/ \/\



(I) was prepared previously by Edinger1, who reported the formation of a double salt with stannous chloride; and by Jan¬ sen, who obtained a chelated complex ion containing divalent nickel and two moles of the mercapto compound2. The present preparation followed Edinger’s method of reduction of quinoline 8-sulfonyl chloride.

The mercaptan is practically insoluble in water; soluble in alkaline solutions, and in alcohol. In solution, particularly in alkali, it is oxidized in contact with air to a non-acidic substance, which gradually precipitates. This insoluble material appears to be a disulfide (III). When run through the regular drop tests with about 78 inorganic ions, the reagent precipitated in acid solutions. In alkaline solutions, colored solids containing metal were obtained with copper (ic), silver, cobalt, nickel, plat¬ inum, and palladium. The composition of these precipitates has not been determined.

The mercaptan is not adaptable to analytical use, because of its great instability in the presence of air. There is, however, one point which may have a theoretical significance. Comparing the reactivity with that of oxine under comparable conditions3, it is seen that (I) reacts with fewer metals, and those which give strong tests are the metals deep in the troughs of the atomic volume curve. This may be related to the fact that scale models of the two molecules show less available space for a chelating metal with (II) than with (I).


1. Edinger, Ber. Ul, 937 (1908).

2. Jensen, Z. anorg. allgem. Chem. 229, 280 (1936).

3. Lundell and Hoffman, “Outlines of Methods of Chemical Analysis”, p. 115. John Wiley and Sons, New York, 1938.

Washington & Lee University


Some Substituted Phenolsulfonephthaleins

J. R. Taylor, R. S, Rosenfeld and J. W. Martin, Je

The introduction of substituents into the phenolic residues of phenol red (I) causes a marked change in the value of the dissociation constant of the phenolic group. The direction of the effect is that which might be expected from the behavior of the simple substituted phenols.












The pK of phenol red is 8.0 and the color change interval, (yellow to red) is from pH 6.4 to 8.2. Introduction of alkyl groups into the phenolic rings yield weaker acids, such as thymol blue (II), with pK 8.9, and change interval pH 8.0 to 9.6. Halo¬ gen, and especially the nitro group, has the opposite effect of in¬ creasing the acidity. Thus, bromphenol blue (III) has a change interval of pH 3.0 to 4.6, and the corresponding tetra-nitro com¬ pound changes between pH 2.8 and 3.8.

Substitution on the sulfobenzoic acid residue might be ex¬ pected to have a much smaller effect on the indicator pK. Three compounds halogenated in this ring, prepared by Harden and Drake,2 showed essentially the same color change, and through the same interval, as phenol red itself.

Since a number of substituted sulfobenzoic anhydrides and sulfobenzimides (saccharins) were available in this Laboratory from a previous investigation, it seemed to be of interest to ex¬ tend the list of dyes with the purpose of testing further the effect of substitutes in the sulfobenzoic acid ring.

The method of preparation was in general that of Harden and Drake2. An excess of phenol was stirred and heated with the sulfobenzoic acid derivative and fused stannic chloride. Un¬ reacted phenol was removed by steam distillation; the dye was leached out with soda solution, and purified by several successive precipitations. The dyes prepared were those tabulated below according to the parent sulfobenzoic acid. The amino compound was prepared by reduction of phenol aminosulfonepththalein.

Parent Anhydride Indicator pK Color change

4-Bromo-sulfobenzoic anhydride 7.8 yellow to purple

4,4-Iodo-sulfobenzoic anhydride 8.1

4,6-Diiodo-sulfobenzoic anhydride 7.9


4.5.6- Tribromo-sulfobenzoic anhydride 8.0

4.5.6- Triiodo-sulfobenzoic anhydride 7.6

3-Nitro-sulfobenzoic anhydride 7.6

3-Amino-sulfobenzoic anhydride 7.9

The indicator pK values were determined by comparison of paired Gillespie tubes and buffer solutions of known pH.

It is apparent that the pK values of all these compounds are practically the same as that of phenol red. In each case the change interval was approximately pH 6.5 to 8.5, the color being about the same for all the indicators. In addition, the sec¬ ond color change, characteristic of all the sulfonephthalein dyes in strongly acid solutions, was found to set in at about pH 1.5, the color changing from yellow to orange-red as the pH de¬ creased..

The color of the alkaline form of the sulfonephthalein dyes is commonly attributed to the presence of a negative charge which may appear at two different points in the molecule3. In the same way, the deepening of color in strongly acid solutions may result from an oscillating positive charge. There appears to

Alkaline form Strong acid form

be no mechanism by which the substituents in the compounds described here could affect the possible distribution of charges. It is possible that such an effect would be obtained from a deriv¬ ative of 4-nitro- rather than 3-nitro-o-sulfobenzoic acid, so that the nature of the color change would not be the same as that of phenol red. This possibility will be tested later.


Several new substituted sulfonephthaleins, with the substit¬ uents in the sulfobenzoic acid residue, have been prepared. Their indicator properties are essentially those of the unsubstituted phenolsulfonephthalein.


1. Kolthoff, “Acid-Base Indicators”, Transl. by Rosenblum, p. 129. Mac¬ Millan, New York, 1937.

2. Harden and Drake, J. Am. Chem. Soc. 57, 562 (1929).

3. Yoe and Sarver, “Organic Analytical Reagents”, p. 73. John Wiley and Sons, New York, 1941.

Washington & Lee University


Reactivities of Certain Organic Compounds with Inorganic Ions

F. H. Fish, P. J. Walkauskas and M. Fox

Thirty organic compounds have been tested since our report was made last year. This makes a total of two hundred and eighty compounds investigated at Virginia Polytechnic Institute.

Eighteen out of the thirty compounds tested during the session 1941-1942 gave colored solutions or precipitates. The majority of these reactions, however, appear to be of little value from the standpoint of analytical chemistry. Ferric iron was the most reactive of the seventy-six inorganic ions included in the tests.

The following compounds were found to be reactive and will be investigated later :

1. 4-Ethylaminobenzoic acid gives a yellow precipitate with palladium ions and a black precipitate with silver ions. >

2. p-Tolyhydrazine hydrochloride gives a black precipitate with silver ions.

3. Di-acetoacetyl 2 (4'-aminophenyl) produces a deep orange precipitate with uranium ions.

4. 2,5-Diethoxy-4-acetoacetylaminophenol gives a deep yel¬ low precipitate with cupric ions.

Virginia Polytechnic Institute

Progress Report on Inorganic Analysis with Organic Reagents

E. Louise Wallace and Alfred R. Armstrong

Eighty organic compounds were tested by spot-plate tech¬ nique during the 1941-1942 session, making a total of two hun¬ dred and fifty substances investigated at William and Mary.

Of the eighty compounds tested, thirty-nine gave color re¬ actions and seven behaved as acid-base indicators. 1-Phenyl- 3-methylpyrazoline shows some promise as a reagent for haf¬ nium; ceric, auric, ferric, ruthenium, and chloroplatinate ions interfere.

College of William and Mary


Organic Solvents and Wash Liquids in Analytical Chemistry

Landon Arndale Sarver

Of all the manifold uses of organic substances in inorganic analysis, none are more ancient or less appreciated than the employment of liquid compounds of carbon as solvents and for the washing of vessels and precipitates.

It is not uncommon for this new-old field of knowledge to be referred to as a product of the last fifteen or twenty years. Just the other day I read an article in which it was stated that the use of organic reagents had increased steadily since the use of a carbon compound by Peter Greiss in 1879, and especially after the excellent results obtained with dimethylglyoxime in 1905. It was at least intimated by these writers that the year 1879 saw the first application of an organic compound of any kind in chemical analysis, and that the first method of any real practi¬ cal value came in 1905.

Fortunately, we have here in Virginia, due to the able leader¬ ship of Professor Yoe, a group that is better informed on organic reagents than can be found in most parts of this country. Never¬ theless, it may still come as a surprise to some of you that an important paper was published on the subject one hundred and eleven years ago! I make this statement from my certain knowledge, but I feel sure that still more ancient references will be found when the literature has been searched with sufficient diligence.

The foundation for the well-known perchlorate method for the determination of potassium was laid by Serullas in 1831, when he discovered that potassium perchlorate is a great deal more soluble in ethanol than are the perchlorates of sodium and lithium. Even today, this is still one of the very best meth¬ ods for the separation of the alkalies.

As a matter of fact, publications on organic reagents have have been fairly regular since 1856 ; at least one paper has been published every twelve months for the past seventy-one years; and there have been not less than seven annually for the past half-century. Investigators had already been active for three- quarters of a century when the analytical value of dimethyl¬ glyoxime for the determination of nickel was first disclosed to the world.

Personally, I think that l-nitroso-2-naphthol has been very valuable for the separation of cobalt from nickel in acid solu¬ tion, and the first work on this was published in 1885. In re¬ cent years, both Dr. Yoe and myself have been active in investi¬ gating the behavior of some derivatives of l-nitroso-2-naphthol as colorimetric reagents for cobalt.

While the bulk of the earlier researches on organic analytical


reagents were concerned chiefly with colorimetric qualitative tests for various ions, particularly nitrates and nitrites, it just happens that several of the very oldest had to do with solvents. The use of ethanol in the perchlorate method for potassium has already been mentioned. Struve, in 1869, discovered that traces of iodine could be detected by extracting it from aqueous solu¬ tion with carbon disulfide; iodides and iodates could also be detected by first liberating the iodine and then extracting it. And Kersting, in 1863, tested potable waters for nitrates by means of an alcoholic solution of brucine.

Solvent Functions of Organic Liquids

Organic liquids may be used as solvents for a variety of pur¬ poses, among which are the following :


Solvent Functions of Organic Liquids

I. Washing

[a] Vessels

[b] Precipitates

[c] Other liquids

[d] Gases

II. Drying

[a] Vessels

[b] Preciptates

[c] Other liquids

[d] Gases

III. Extractions

[a] Liquid-solid

[b] Liquid-liquid

[c] Liquid-gas

IV. Change in Ionic Activities

[a I) Differential crystalli¬ zation

[b] Control of dissociation

[c] Intensification of colors

V. Miscellaneous Uses

[a] Solvents for reagents

[b] Protective layers

[c] Control of foaming

[d] Collection of precipi¬ tates at interface

[e] Aids to distillation

[f] Reducing post-precip¬


I. Washing. The washing of [a] laboratory vessels, and [b] quantitative or qualitative precipitates are probably the oldest uses for organic liquids in analytical chemistry ; and only a careful perusal of the early literature would reveal the first ap¬ plication of this kind. In addition to this, they are also fre¬ quently employed for washing other liquids and solutions [c] with which they are immiscible, and [d] for the scrubbing of gases and vapors.

II. Drying. Some organic solvents are miscible with water, and possess at the same time a high vapor pressure at ordinary temperatures, while in other cases a substance of low vapor


pressure is mutually miscible with water and another liquid of high vapor pressure. Acetone, for example, can be used for the drying of [a] pipets and other vessels, and [b] of precipitates; but the same result can also be accomplished by rinsing first with alcohol, and then with ether. Further, as was the case with washing, organic liquids can be used for the drying of [c] other liquids, or [d] for the drying of gases.

III. Extraction. The first recorded use of an organic solvent of which we are at present aware was [a] a liquid-solid extraction; Serullas found in 1831 that if the dehydrated mixture of sodium and potassium perchlorates be treated with ethanol, the sodium salt dissolves, and potassium perchlorate can be filtered off. The third recorded use of an organic analytical reagent was [b] of a liquid-liquid extraction ; for Struve, in 1869, extracted traces of iodine from aqueous solution, and con¬ centrated it in a small volume of carbon disulfide so as to in¬ tensify its color. Organic liquids may equally be employed [c] to absorb some constituent from a gaseous mixture.

IV. Change in Ionic Activities. The addition of organic liquids to aqueous solutions often brings about profund changes in the properties of such solutions. The use of ethanol for de¬ creasing the solubility [a] of lead sulfate in water or dilute sulfuric acid is well-known. Acetone [b] has been employed extensively for intensifying the blue color in the thiocyanate test for cobalt; it does this, of course, by shifting the equilibrium in favor of the undissociated cobalt thiocyanate. The same gen¬ eral effect can also be accomplished in the case of colorless sub¬ stances [c], whenever it is desired to eliminate the interference of some ion with an analytical reaction.

V. Miscellaneous Uses. The second recorded application of organic substances in analytical chemistry was [a] as a solvent for an added reagent, when Kersting, in 1863, detected nitrates in drinking water by means of an alcoholic solution of brucine. Liquids that are immiscible with water [b] can be used as protective layers to eliminate the effects of oxygen or carboy dioxide in the air. Substances such as octyl alcohol

[c] can be employed for the control of foaming. Liquids that are immiscible with water, such as benzene or ether, can serve

[d] for the collection of very small precipitates at the interface. Liquids that are immiscible with water, like toluene or heptane, are employed regularly as aids to distillation [e] in the determi¬ nation of moisture. And certain unsaturated aldehydes, notably acrolein and crotonaldehyde, have proven themselves invaluable in [f] reducing the post-precipitation of zinc sulfide along with cupric sulfide.

Factors Affecting the Choice of Solvent

A number of factors have to be considered in choosing a sol¬ vent for a given purpose.



Factors Affecting the Choice of Solvent

1. Suitability for purpose

2. Cost

3. Toxicity