Qualitative Study of the Color Reaction of Phosphomolybdic Acid CHIEN-PEN LO'
AND
LUCY JU-YUNG CHU
National Rerearch Institute of chemistry, Academia Sinica, Kunming, China
PROCEDURE. Color Reaction of Phosphomolybdic Acid and Molybdate with Sugars. One milliliter of the sugar solution (5%) was added to the proper amount of the reagent. The whole was boiled for 3 minutes, the volume of the solution being kept unchanged by constantly adding water to it. Six common sugars were tested against phosphomolybdic acid, acidulated phosphomolybdic arid, ammonium molybdate, and acidulated ammonium molybdate. The results are tabulated in Table I. Color Reaction of Phosphomolybdic Acid with Metals and Reducing Compounds, The metal or the solution of the reducing compounds (1 to 2 ml.) was added to 3 ml. of the test solution. The color reaction usually took place a t room temperature; in only a few cases was warming or boiling necessary. The reducing compounds were 1%aqueous solutions, if not otherwise specified. The results are tabulated in Table 11. The phosphomolybdic acid did not give color reaction with formaldehyde, formic, lactic, and oxalic acids even when the solution was boiled.
THIS
short paper reports the color reaction of phosphomolybdic acid with six sugars, twelve metals, and thirteen other reducing agents.
REAGENT.Phosphomolybdic acid solution (test solution), 1 gram of P205.24 Mo03.zH20 (Schering-Kahlbaum), dissolved in 100 ml. of water.
Table I. Color Reaction of Phosphomolybdic A c i d and Molybdate with Sugars 1%
Sugar Glucose Galactose dructose Maltose Lactose SucroseC
Test Solution (3 MI.) Light green Light green Bluish green Green None Green
Test Solution (3 MI.) 3N HzSOc (1 MI.)" Light green Green Deep bluish green Green Light green Deep bluish green
+
1% Ammonium Molybdate (3 MI.)* None None None Blue None None
Ammonium Molybdate (3 MI.) 3 N H2804 (1 MlJb Blue Blue Deep blue Bluish green Blue Deep blue
+
1 Present address, School of Chemistry, University of Minneaota, Minneapolis, Minn.
a Reagent retained yellow color after boiling 3 minutea. b Reagent remained colorless after boiling 3 minutes.
e Sucrose solution gave no precipitate of cuprous oxide when boiled with Fehling's solution.
Table II.
Separation
AI (powder)
Color Green, bluish then blue None
Zn (dust)
Blue
Fe (powder)
Green, bluish then blue Green, bluish then blue Green, bluish then blue Blue Bluish green None
Ni (granules) Sn (granules) P b (granules) Sb (granules) Bi (granules)
Aa (granules) Cu (granules)
Bluish Blue Bluish Bluish Bluish
Kreen sulfate JO.l%) green green Ferrous ammomum SUIfate S t a n n o u s c h l o r i d e Blue (0.1% i,n 0.1% HCI) Sodum bisulfite Green, bluish then blue
%reus
Sodium thiosulfate
Green, bluish then blue
Sodium hydrmulfite Potassium iodide
Deep blue None
Potasaium ferrocyanide
Bluish green
Hydroxylamine hydrochloride
None
Hydrazine hydrochloride Phenylhyd,rarine hydrochloride p-Aminophenol hydrochloride Hydroquinone
Green, bluish then blue Deep blue
FRANK KlPNlS
Remarks green, Color changed very slowly Blue color roduced when concd! H8904 added and mixture warmed Color produced immediately green, Color changed very slowly green, Color changed very dowly green.
Research Laboratories, Endo Products, Inc., Richmond Hill 18, N. Y.
D
URING the course of a research investigation, the problem of the removal of large quantities of hydrogenation catalysts, such as Raney nickel, platinum, or palladium, from the reduction medium was encountered. The usual methods involve filtration through paper by suction or use of the centrifuge. The former operation is by no means satisfactory, since the finely divided catalyst often passes into the filtrate, and, in addition, the pyrophoric nature of these metals produces sparking and charring of the filter paper. This becomes a definite fire hazard when large quantities of catalyst and inflammable solvent are handled. RemovaL of the catalyst by centrifugation often gives better results, but involves more manipulation, which may be deleterious to easily decomposed reductiqn pfoducts. A procedure which has given good results but does not suffer from the deficiencies listed above, entails the use of a filter aid, such as Dicalite 4200,or its equivalent, spread in a layer about 1 cm. thick over filter paper seated in a Buchner funnel of appropriate size. This technique, which is by no means a new one in the industrial or analytical field, gives sparkling filtrates completely free of catalyst, and minimizes the possibility of ignition of the solvent or metal. Test runs on various compounds have indicated that little if any material is adsorbed during this treatment, and the noble metal catalysts may be recovered without difficulty. This procedure is advantageously modified in most cases by including the filter aid with the compound to be hydrogenated so that it is present during hydrogenation. This tends to give a better suspension of the catalyst and in many cases a better color sf the finished product is obtained.
Color developed slowly Color developed slowly Bluish green color produced when dilute H a 0 4 added and mixture boiled Color developed slowly Color developed slowly
green
green,
Color c h a n g e d v e r y siowly; more rapidly n was boiled green, Color chaniged slowly; more rapidly if solution was warmed Bluish green color developed when solution was sliehtlv warmed Color changed to reddish brown when H&Ol added Bluish green color developed when solution was boiled
- -
green,
Catalysts From
Hydrogenation Reaction Mixtures
Color Reaction of Phosphomolybdic A c i d with Metals and Reducing Compounds
Reducing Substance Mg (turnings)
OF
Blue Blue
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