AUGUST 15, 1940
ANALYTICAL EDITIOK
459
Summary
4 spectrophotometric investigation of the colorimetric determination of copper with triethanolamine included a study of the effect of concentration of the reagent, and of ammonium, sodium, and potassium salts on the transmission of copper-triethanolamine solutions; and a test of the conformity to Beer’s law a t several concentrations of triethanolamine. A comparative study of the ammonia method was also made. There is little difference in the sensitivities of the copperammonia and copper-triethanolamine methods, though the latter is slightly more sensitive a t low concentrations of copper.
Acknowledgments The authors wish to thank R. H. Muller, Washington Square College, New York University, for suggesting the possibility of using triethanolamine as a colorimetric reagent for copper. The J. T. Baker Chemical Company research fellowship in analytical chemistry for 1938-39 was awarded to one of the authors (C. J. B.). They are very grateful for this assistance.
Literature Cited (1) Barton and Yoe, IND.ENG.CHEM.,Anal Ed., 12, 166 (1940). (2) Goethals, Z . anal. Chem., 104, 170 (1936).
Identification of Alcohols By Means of the Optical Properties of the Esters of Carbanilic Acid BARTLETT T. DEWEY AND NORhIAN F. WITT North Pacific College of Oregon, Portland, Ore., and University of Colorado, Boulder, Colo.
T
H E esters of carbanilic acid, the phenylurethans, have been recommended as derivatives for the identification of alcohols by Hofmann ( 2 ) , Snape (6), and hlorgan and Pettet (4). Primary and secondary alcohols react readily with phenyl isocyanate to yield crystalline phenylurethans. I n the presence of moisture, diphenyl urea is also produced. Some difficulty is experienced in removing the latter compound, so that accurate melting points may be obtained to establish the identity of the alcohol. This investigation was undertaken to determine whether or not the optical constants of the phenylurethans could be used to identify these compounds and distinguish them from diphenyl urea. The phenylurethans were prepared from fifteen normal primary alcohols according to the directions of Kanim (3),and were recrystallized from petroleum ether. (The ethyl alcohol was produced by the fermentation process; the other alcohols were manufactured synthetically.) The decyl, undecyl, and dodecyl esters, after subsequent recrystallization from 50 per cent ethyl alcohol, yielded larger and more regularly shaped crystals. The crystal system, optical character, optic sign, sign of elongation, dispersion, and extinction angle were determined by the methods described by Winchell ( 7 ) and by Chamot and Mason ( 1 ) . The urethans are soluble in the oils usually employed for immersion liquids in the determination of refractive indices. Glycerol and \vater and solutions of potassium mercuric iodide in glycerol were found suitable for this purpose.
sponding to the beta value previously determined for the urethan in question. A crystal is rotated t o the position of extinction with the long axis of the crystal more nearly parallel to the 6 o’clock-12 o’clock direction in the polarizing microscope. In this position, most of the crystals will not be visible if the alcohol is the one anticipated. The crystal forms of the ethyl, amyl, hexyl, and benzyl esters are such that their orientation should be estahlished by means of an interference figure before applying the test for the refractive index. As a confirmatory test the value of gamma, or (for the nonyl ester) alpha, may be checked in a similar manner. In the determination of alpha or gamma, the long axis of the crystal should be more nearly parallel with the 3 o’clock-9 o’clock direction in the polarizing microscope.
All the compounds investigated belong to the monoclinic system, and their optical character is biaxial. Their other characteristics are presented in Table I. Not all the optical data could be obtained for each of the compounds because of the difficulty involved in orienting the crystals properly. The determination of the optical sign is difficult, since all of the substances investigated, with the exception of the benzyl ester, have large optic angles. Of the properties investigated, the refractive indices are the most characteristic. They serve to est’ablish bhe identity of the urethans and to differentiate them from diphenyl urea. The undecyl ester sometimes shows slightly lower indices when recrystallized from 50 per cent ethyl alcohol.
T ~ B LI.E OPTICAL PROPERTIES O F SOME ESTERSO F CARBANILIC B C I D AND O F DIPHENYL UREA,
The procedure followed in identifying an unknown alcohol is similar to the method applied by Poe and Sellers ( 5 ) for the identification of strychnine. The ester is prepared and recrystallized from petroleum ether and allowed to dry in air. A few of the crystals are suspended in a medium of a refractive index corre-
In order to test the possibility of identifying an alcohol when water is present, methyl, ethyl, propyl, butyl, and amyl alcohols were mixed with equal parts of water and treated with phenyl isocyanate. The resulting mixtures of the urethans and diphenyl urea were extractled with boiling petroleum ether. The optical characteristics of the crystals of the urethans formed in the presence of diphenyl urea were not altered and the urethans were readily identified by their refractive indices. Mixtures of methyl and ethyl, propyl and isopropyl, and butyl and isobutyl alcohols in equal proportions were made.
Ester
121ethy1 Ethyl n-Propyl n-Butyl n-Amyl n-Hexyl n-Heptyl n-Octyl n-Xonyl n-Decyl n-Undecyl n-Dodecyl Benzyl Phenylethyl Phenylpropyl Diphenyl urea
.\Ielt- Extincing tion Optic Refractive Indices Elonga- DiaperPoint Angle Sign Alpha B e t a G a m m a tion 8ion
c.
61 52 74 77 78
16 20 33 31 45 40 44 16 36 6 12 27 11 28
45
29
235
40
47 52 50 57 45 40 65 74 60
1.542 1.516 1.525 1.507 1.464 1.465 1.502
1,590
1,5xo
* * * * * * * *
1.667 1.618 1.641 1.655 1.693 1.670 1.615 1.627 1.613 1.605 1.605 1.618 1.679 1.681
* * * t * *
p > u u p v > p v > P
>
1 :i70 1.596
1.596 1,592 1.598 1.589 1.553 1,559 1 570 1 536 1.546 1.548 1.587 1 629
+
1.549
1.604
1,703
f
u >
f
1 583
1.621
>1.703
t
p
1 :472
.. ..
>
p Y p > v p > v
None p >
Y
Sone Sone None u >
p
D ‘z Y
p
>Y
460
INDUSTRIAL AND ENGINEERING CHEMISTRY
Urethans were prepared from these mixtures and recrystallized from petroleum ether. The mixture of ethyl and methyl did not produce crystals characteristic of the individual urethans. The other mixtures yielded crystals which could be identified. Care must be exercised to prevent one of the components from being separated out by the solvent.
Summary The optical crystallographic data for fifteen esters of carbanilic acid have been determined and compared Kith similar data for diphenyl urea. The optical properties provide a means of identifying the urethans even when they are mixed
VOL. 12, NO. 8
with diphenyl urea. A method for confirming the identity of an alcohol is outlined.
Literature Cited (1) Chamot and Mason, “Handbook of Chemical Microscopy”, New York, John Wiley & Sons, 1930. (2) Hofmann, Be?., 18, 518 (1885). (3) Kamm, “Qualitative Organic Analysis”, New York, John Wiley & Sons, 1932. (4) Morgan and Pettet, J . C h a . SOC.,1931, 1121-6. (5) Poe and Sellers, IXD EX. CHEM.,Anal. Ed., 4, 69 (1932). (6) Pnape, Be?., 18, 2428 (1885). (7) Winchell, ”Elements of Optical Minerology”, New York, John W l e y & Sons, 1937.
Method for Analysis of Boiler Scales and Sludges F. K. LINDSAY AND R. G. BIELENBERG National Aluminate Corporation, Chicago, Ill.
Detailed procedures are given which employ colorimetric and turbidimetric methods in conjunction with a Phototester for the analysis of boiler deposits. Tabulations show the results obtainable with these procedures as compared with time-consuming gravimetric methods involving reprecipitation of the constituents sought. Owing to the difficulty normally encountered in obtaining a representative sample from the large surface of a boiler, a high degree of analytical accuracy is usually not so important as rapidly and conveniently obtained knowledge of the type of deposit involved.
I
S COSSIDERIKG analytical methods for the chemical analysis of a boiler scale, it is important to select procedures that will accurately depict the type of chemical deposition that has been formed-that is, whether the deposit contains unusual amounts of calcium, magnesium, aluminum, iron, silicate, sulfate, carbonate, or phosphate. Owing to the large amount of surface area available in a boiler on which a deposit may form, two different samples will not check perfectly as to chemical analysis. If, therefore, a particular sample of boiler scale has a calcium oxide content of 30.0 per cent, any method of analysis that finds a calcium oxide content in this sample of from 29.0 to 31.0 per cent is satisfactory. The same generality applies to the other constituents that are likely to be found in a boiler deposit. Inasmuch as time is always a t a premium in an analytical laboratory, the method that allom the required degree of accuracy in the shortest time is the most desirable, especially for plant control purposes. Gravimetric procedures, as applied to scale analybis, are usually time-consuming. This is particularly true with some types of deposits. For example, scales that contain considerable phosphate along with calcium, iron, and aluminum require the addition of a standard iron solution, as well as the reprecipitation of the iron and aluminum oxide group found. This sort of analytical procedure when used solely for plant control purposes is time-consuming. If the reprecipitation
step is omitted, the procedure required is still long, and the results obtained are not satisfactory. In analyzing this type of scale gravimetrically the usual procedure is as follows: The phosphorus pentoxide is determined on an aliquot of the filtrate from the silica determination. In precipitating the iron and aluminum hydroxides from another aliquot of this same filtrate, sufficient standard iron solution to react with the phosphorus pentoxide present is added, followed by ammonia. In the precipitation that occurs, the phosphorus pentoxide is thrown down as ferric phosphate, and the iron and aluminum originally present in the deposit are precipitated as hydroxides. The sum of the phosphorus pentoxide present and the ferric oxide added, subtracted from the ignited precipitate, gives the amount of iron and aluminum oxide present in the scale. The ferric oxide is determined on a separate aliquot either by precipitation with cupferron or colorimetrically. Subtracting this result from the iron and aluminum oxides found gives the aluminum oxide present. I n spit’e of the fact that the standard iron solution is purposely added to precipitate the phosphate present and to prevent the phosphate from reacting with and removing calcium a t this stage in the procedure, unless the precipitate referred to above is dissolved and reprecipitation made, considerable calcium may be present in the iron and aluminum oxide, thereby giving a final result that is too high in aluminum oxide and correspondingly low in the amount of calcium oxide found. I n Table I results are given on a phosphate scale as well as on a known mixture containing iron, aluminum. calcium, magnesium, and phosphorus. Analysis was made with and without the reprecipitation of the iron and aluminum oxide group. The results Qf the calcium and aluminum determinations only are given. These data illustrate the necessity of employing reprecipitation. T ~ B LI.E DETERMIXATION O F CALCIUM AND ALuxmuhI Scale Samples Synthetic llixtureb Ah03 CaO .11?Oa CaO Added, % 20.0 30.0 Found by gravimetric procedurec, % 1i: 7 29: 1 25.3 25.1 Found by gravimetric procedured, yo 5.4 35 5 20.8 29.3 Found by simplified procedure, Yo 5.2 36.8 19.6 29.8 0 Scale contained 12.0‘7, loss on ignition, 6.2YC SiO?. 5 4 7 41?03, 5.9(z FezQ3, 35.:% CaO, 2.2Cc MgO. 24.7% PzOS,2 , 5 % 6 0 3 , 1.0070’CO2, 3,952 NazV. b Synthetic mixture contained 5 0 % FclOa, 25.0% PgOs, 2.0% MgO, 20 0% A1203, 30.0% CaO, 10.0% S O ? , 8 . 0 % SOa. c Procedure involved addition of standard iron solution t o precipitate
phosphate present. No reprecipitation employed. d Procedure involved addition of standard iron solution as in ployed reprecipitation of R103 found.
c.
Em-
