1186
ANALYTICAL CHEMISTRY
A plane containing X P and a t right angles to the vertical plane will project on the latter as z'p'. This line cuts the sides of triangle y'w'z' a t f' and g'. f'g' is therefore the projection 011 the vertical plane of the intersection of plane YWZ and that containing X P . Because points f' and g' belong to y'w' and y'z', t,heir projections on the horizontal plane, f and g, should lie on yw and yz, respectively. Point 0 is the intersection of X P and plane YWZ; therefore rp is &ended to intersectfg a t point 0 .
respectively (Figure 4). Points p and p' are similarly obtained b y plotting 49 and 83.5 against 44.5. Produce x'p' t o obtain points f' and g'. Transfer these points vertically down onto the corresponding sides, 2/t and IW, t o obtain f and g. Extend x p to intersect fg at o. The tractional concentrations of the ronipoueutq %rethen given by x
In the graphical solution described for simplicity, the vertical plane containing a and 6 is rotated clockwise so that the t m planes are superimposed (Figure 2). It is evident that the chnngr of scale by addition or multiplicat,ion does not alter thr solution.
2
( o p o x ) = 22 88
IJ = ( n o n y ) ( l - x ) =
22 110
025
=
x
0 75
=
0.13
21.2 x 80
o.;j
=
0.20
Example.
+ 401) + -102 + 60w = 49 20x + lo!/ + 702 + 50w = 44.5 90r + 8 0 ~+ 90z + 65w = 83.5 1'+ !/ + r + w = 1 601
(i)
/('
=
(ro h ) ( l - I) =
(ii) LITERATI'RE CITED
(iii)
(iv) Plot coefficients of I, IJ, 9 and w in ( i ) and (iii) against tlie corresponding coeficient~in (h) to obtain points x', y', ?'. arid w ' ,
(1
l l e h n i k e , Rudolph. "Leitfadeii z u ~ i iGraphiwhrii Hechneii," p. 12. Leipzig arid K i e n . F r a n z Deuticke. 1924,
K w m r 8 : n July 21. 1S.W.
Colorimetric Determination of Vanadium with Benzoylphenylhydroxylamine SUDHIH C H C W R A SfIOhfE' Indian Institic tr of Scierrre. Rnngulore, India
ANADIUhI, as vanadate, has been determined colorinietriVenlly using various organic reagents. The uses of strychnine (6, l b ) , diphenylamine ( 7 , I s ) , and aniline hydrochloride ( 1 4 ) have been reported for the colorimetric determination of the metal. Montequi and Gallego (9) have prepared the conipounds of vanadate ions with 8-quinolinol (8-hydroxyquinoline) and have found the violet-black precipitate obtained from a slightly acid solution to be (CsH8ON)4V2O3. The same workers have separated vanadium from chromium by rstractirig the 8-quinolinol compound with chloroform. Bach and Ti,elles ( 1 ) have determined vanadium in water by ext,racting the quinolate with isoamyl alcohol. Molland (8) employed 8-quinolinol-5-sulfonic acid instead of 8-quinolinol. Chervyakov and Ostrouniov (3) determined minute quantities of vanadium in uranium preparations using p-dimethylaminoaniline. Szebell6dy and Ajtai (1.3) studied the catalytic effect (which was activated with pyrocatechol) of vanadiuni upon the reaction between p-phenetidine and potassium bromate, and determined as little as 0.0006 microgram of vanadium. Findlay and Furman (dq 6 ) extracted vanadium even in microgram amounts from dilut'e sulfuric acid solut,ion by cupferron and ether prior to its estimation by eolorimetric methods. series of allied organic compounds was investigated ( 1 1 ) in order to improve upon the defects of cupferron (ammonium salt of nitrosophenylhydroxylamine). The use of henzoylphenylhydroxylamine, which was first prepared by Bamherger ( 2 ) , as an analytical reagent for the gravimetric determinat'ion of copper, iron, aluminum, and titanium, has recently been described by the author (10). Benzoylphenylhydroxylamine, like cupferron, gives a mahogany red precipitate tyith vanadate ions. The precipitate is soluble in organic solvents such as ethyl alcohol, benzene, and acetic acid. This new organic reagent is not' suitable for the gravimetric determination of vanadium, because a portion of the complex remains in the colloidal condition and passes through the filter paper (Whatman No. 42). In the present investigation benzoylphen?-lhydroxylamine was employed for the colorimetric determination of vanadium. A\
1
Present address. Sational Institute of Sciences, Delhi 8 . India.
APPARATUS AND SOLUTIOYS
.\bsorpt,ion measurements a t various wave lengths were Inade visually with a polarizing spectrophotometer (Gaertner), using a solut,ion thickness of 1 cm. Colorimetric comparisons n-ere carried out using a Duboacq colorimeter. Sensitivity tests were performed in 50-nil. Sessler tubes. pH values of the solutions were measured with a glass electrode. Benzoylphenylhydroxylamine Solution. A 0.2mc solution of I)enzoylphenylhydroxylamine in ethyl alcohol was used in tlie spectrophotometric work. Vanadium Solution. -4. vanadate solution was prepared by dissolving sodium vanadate in distilled water and the vanadiuni content ivas determined by precipitating with cupferron in icecold solutions. A portion of the stock solution was diluted so that the final solution contained 0.05 mg. of vanadium per nil. Diverse Ion Solutions. Standard solutions of ferric alum and titanium sulfate were prepared separately by the usual methods. The other solut'ions were made by dissolving weighed amounts of salt! in distilled water, each milliliter containing 2.5 mg. of the ion in question. Solutions of the anions were prepared from thr alkali nietd salts: sulfates were used for the solution.; of tllr rations. -411 the eheniicals used %yereof analytical rragriit quality. SPECTROPHOTOMETRIC STUDY OF COLORED SOLCTIOIS
In preparing the colorimet,ric solutions used in thi:: stlid!. t h e following procedure was adopted. -4.known amount of vanadium solution ( 1 to 15 nil.) was introduced into a 50-ml. volumetric flask and suitable quarititiee of di1ut.e sulfuric acid were added to adjust the pH of t,he final solution to t,he required value. -4preliminary experinipnt was ear' to regulate the pH of the solutions. ine sollti?n (10 i d . ) was then added and the contents were thoroughly mixed. The resulting solution was dilut,ed with ethyl alcohol (15 nil.) and made to volume with distilled water. After 10 minutes, the absorption due to the solut,ion was measured with the spectroIJhotoineter. Effect of pH. The orange-red color formed by benzoylpheriylhydroxylamine with vanadate ions was influenced by the pH of the solutions. The variation of absorbancy (log Io/Z) of the colored solution, containing 10 mg. per liter of vanadium, with pH is shown in Figure 1. A s the field of view was not very bright at 480 mp, it was convenient to take thp readings at 510 nip. The
V O L U M E 23, NO. 8, A U G U S T 1 9 5 1
1187
intensity of the color reached a maximum when the pH of the solution was between 1.9 and 2.8. .ibove pH 2.8 the color did not, develop fully, while belo\T pH 1.9 it faded gradually. Effect of Benzoylphenylhydroxylamine Concentration. For solutions with a h a 1 volume of 50 nil., 10 ml. of benzoylphenylhydroxylamine solution (0.2y0) were sufficient for the full development of color when vanadium concentrations up to 15 mg. per liter were used in the, plI range of 1.9 to 2.8. The intensity of the color did not iricwaw \vhrii more organic reagent iv:ir; u a r d .
The contents were thorough1)- mixed mid the solution was ~iiade to the mark with distilled water. After 10 minutrs, the absorption due to the solution was measured a t 510 mp. I n general, the effect of 500 mg. per liter of diverse ions was studied; when interference vas noticed, smaller amounts were used until the change in absorption was not more th:w 2y0 of the theory. The results are recorded in Table I. Iron reacted with t,enzo\lphenylhydros~laniiIie to give :L pink colored solution and the s-riisitivity of this reaction wa$ as high as that of vanadium. Titanium interferrd when preserit in more than 50 nig. per liter, bectiuse it formed a yellow complrr with the organic reagent. .iluniiriu~n, nimganew, :ind many other ions interfered with the color re:wtion, prol)abl>. I)ecuuse the>reacted wit,h the variadxtr ions,
Table 11. Ueterrnination of \-ariadiurn \ + i t t i Benzoylphenyl h>-droxylamine (Total volunie of solution = 50 ml.) Vanadium
Taken, Mg.
Benzoylphen,-lhgdroxylaininr Added. Q.
Vanadiuni Found, Mg.
0.01
0.176 0.494 0.660 3.100 6.400
0.176 0,500
0.02 0.02 0.20 0.32
0.650 3.160 6.510
2
4
I pH.
5
--0.110
DETERMINATION O F V.4NADIUB.I USING A I)I.HOYCV COLORIMETER
6
Figure 1. Effect of pH
Effect of Vanadium Concentration. Absorption curves of the colored solutions a t a pH of 2.5 are shown in Figure 2. Absorpt,ion measurements were made a t wave lengths of 480 t80620 nip n i t h solutions containing 1 t o 15 mg. per liter of vanadium. Measurements a t wave lengths lese than 480 mp could not be carried out with the spectrophotometer. The absorption \vas maximum a t 480 mp in the range of wave lengths studied, and with a solution containing 15 mg. per liter of vanadium the :thorption a t this wave length \\-as 83.2%. The rolored solutions obeyed Beer's law. Stability of Color, The oi,ange-retl color formed by heuzoylphenylhydroxylamine with vanadate ions was stable for :Lbont 3 hours a t pH 2.6 hut, the color faded slo~vlythereafter.
Table I.
Error. MS. -0 001 -0.ooti TO.0lU -0.060
Vanadium was estimated with ~ ~ e r i z o ~ I p l i e n y l h y d r o s ~ l a ~ i i i ~ ~ t ~ using a Duboscq colorimeter. The concent,rations of vanadium in the sample and standard did not differ by more than 25yo,. The vanadium content (0.175 to 6.51 mg.) of different samples of the sodium vanadate solution \vas determined by the ~~rocetiure described below. The results are given in Table 11.
CURVE. VANADIUM,m# I
15.0
2
10.0
7.0 5 .O
3.0 I .o
Effect of Diverse Ions Added as
Amount Permissible, nfg./L.
0 0 360 50 500 23 500 500 120 10 15
Effect of Diverse Ions. I n measuring the effect of the diveise ions, the vanadium solution containing 0.5 mg. of vanadium was taken in a 50-ml. volumetric flask and a known amount of the solution containing the ion in question was added. T o this was added dilute sulfuric or dilute ammonium hydroside solution t o maintain the pH of the final solution between 2.4 and 2.6. The benzoylphenylhydroxylamine solution (10 ml. ) was added, followed by the addition of ethyl alcohol ( I 5 nil.).
0
480
510
-
540
3
580 WAVE LENGTH,
620
my
Figure 2. Absorption Curves of %-anadiuinBenzoylphenyl hydroxl lamine Complex
I n a 50-ml. volumetric flask, the vanadate d u t i o n wns acidified with 0.2 to 2.0 ml. of 1 S sulfuric acid to adjust the pH of the final solution to approximately 2.4. -% weighed excess of 1)eiizoylphenylhydroxylamine dissolved in ethyl alcohol was added. followed by further alcokiol SO that the final solut,ion contained 50 to 70% alcohol. T h e solution was diluted to the mark with distilled water, and the color developed was compared with that of the standard prepared in a similar manner. Any uiiriecessary delay in the colorimetric measurements was avoided : otherwise the concentration of vanadium in the solution slowly increased owing to the evaporation of alcohol. The solution should not contain more than 6.5 mg. of vanadium, because slight precipitation of the vanadium complex occurred at higher concentrations,
ANALYTICAL CHEMISTRY
1188 Sensitivity of Color Reaction. Sensitivity measurements were carried out in 50-ml. Nessler tubes, using the same quantity of reagent ~olutiouin the blank. It was found that the s m l l e s t amount of vanadium that oould be detected with bensoylphenylhydroxylrtmine was 0.33 mg. in 1liter of solution. CONCLUSIONS
Beneoylphenylhydroxylamin~ provides a simple and sensitive method for the colorimetric determinetion of vanadium. Moreover, this organic reagent can be prepmed easily and preserved indefinitely. Vanadium can be estimated in presence of certain ions, hut iron and aluminum, even in traces, interfere with the procedure. Further work will he required to eliminate the interferences caused by iron and aluminum which are commonly associated with vanadium. ACJCNOWLEDGMMT
The author wishes to express his sincere thanks t o Sir J. C. Gbosh, director, Indian Institute of Science, for the opportunity
to carry out this investigation and to S. C. Bhrtttaeharyya for his suggestions and help. LITERATURE CITED
fli , . Baoh. J. M..and Trelles.R. A.. Bol. obras sanit. nacidn iBuenos ~ i A ) , 5i27 , (1941). ( 2 ) Bamberger,E.,Bel., 52,1116 (1919). (3) Chewakov, N. I., and Ostroumov. E. A,, Zavodskaya Lab., 3, x..m. iim41. ~...~,. (4) Findlay. S. P., and Furman, N. H.,Manhattan District, Document M.S.A.4.-2900 (1945). ( 5 ) Furman, N. H., Meson, W. B., and Pekola,J. S., ANAL.CHEM.. 21,1325(1'340). (6) Gregory, A. W., Chem. Mews. 100. 221 (1009). (7) Meaurio, V. L., Ann. chim. anal., 23,47 (1918). (8) Molland, J., Compt. rend., 210, 144 (1940). (9) Montequi, R.,and Gallego, M.,Andes. SOC. espaii.As. p " h ,32. 134 (1934). (10) Shome, S.C.,Ambsl. 75,27 (1950). (11) Shome, S. C., Current Sci.. 13,257 (1944). (12) Snell, F. D.,and Snell. C. T., "Colorimetric Methods of Andyais,"p. 372, New York, D. Van Nostrand Go., 1936. (13) SuebellBdy,L..and Ajtai, M., Mik~ochemie,26, 87 (1930). (14) Zilberminte,V. A,, and Florenskii, K.P.,Ibid., 18, 154 (1035).
1,s-Dinitronaphthalene I
47.
Contributed by WALTER C. McCRONE, Armour Research Foundation of Illinois Institute of Technology, Chicago 16, 111.
XCELLENT crystals of 1,S-dinitronaphphthalene can be ob-
E tained from alcohol or benzene.
Crystals from benzene lie preferentially on the basal pinacoid. On a micraswpeslide thymol e m he used to give perfectly formed crystals for morphological and optical study (Figure 1).
dome, loll), are also usually present; from benzene the basal pinacoid, (001/, is thedominant form. Axial Ratio. a:b:c = 0.758:1:0.359, 011 A Oil Interfacial Angles (Polar). 110 11 110 = 74'20'; = 39' 26".
data). Formula Weight. 218.16. Density. 1.587 (flotation and pycnometer); 1.591 (calculated from x-ray data). Principal Lines d
7.52
6.27
'
A
5.72 5.34 5.09 4.87 4.63 4.34 4.11 3.92 3.80 3.67 3.47 3.08 3.04 2.97
/ i
A.
0.8
0.8
0.1 0.2 0.2 0.7 very weak 0.2
0.2
0.9 Very weak 0.2
0.1 1.0 Very weak
d 2.85 2.77 2.71 2.67 2.64 2.55 2.48 2.44 2.38 2.33 2.26 2.22 2.19 2.14 1.89 1.87
IfIi 0.6 0.8 Very weak Very weak Very weak Very weak 0 3 0.2 Very weak Very weak 0.5 Very weak Very wesk Very weak 0.05
0.05
B
Figure 1. 1,s-Dinitronaphthalene B.
I .~ f& 0.3
Form I1 growinq fmm melt Form I crystallized from thymol on miomsoope slide
Although l,%dinitronaphthalene has a t least two unstable plymorphic forms, the latter have been obtained only from the melt on a microscope slide. CRYSTAL MORPHOLOGY Crystal System. Orthorhombic. Form and Habit. From alcohol as flat rhombs lying on the macropinamid, {lWI;the prism form, I l l O ) , and the brschy-
OPTICALPROPERTIES Refractive Indexes (5893 .4.; Z5O C,). a = 1.634 =k 0.002. 8 = 1.763 =t0.005. y = 1.86 (calculsted from a,8,and 2V). Ontic Axial Andes. 15893 9.:25" C.). 2V = 80'. D k e r s i o n . Very stronp, v >'r Optic Axial Plane. 0011 Sign of Double Refraction. Segative. bmbe Bisectrix. a = a. Molecular Refraction ( E ) (5893 8.;25' C,), = 1.750. R(ca1cd.) = 54.1. R(ob3d.j = 56.0.
q a x
