V O L U M E 24, NO. 11, N O V E M B E R 1 9 5 2 s-ray spectrometer technique. Thus the concentration of clay, the type of saturating cation, the nature and amount of solvating compound, the relative humidity of the environment during drying, and the presence of accessory minerals all influence the intensities of the diagnostic basal reflections, on which the analysis is based. It is suggested that a preliminary qualitative analysis of the mixture to be analyzed be made before the final conditions are selected for the quantitative study.
1789 Thrs liwarit\- and slope of the working curves attest to the utilit?- 01 the. method adopted for the quantitative analysis of clay minerd- in polycomponent mistures. The accuracy of 5 to 10% obtained meets the requirements of most analyses of this nature and the method should prove of interest to workers in the petroleum industry, to highway engineers, and to soil scientists Greater accuracies than presented may be realized by the judicial selection of “standard” clay minerals, applying corrections for differential x-ray absorption and rate of sedimentation, etc., but in conderation of the complexity of the natural clay mineral mixture-, to the analysis of which the method must finally be applied, it would appear that the development of more precise methods should await further progress in the identification and srparation of the constituents of naturally occurring play minc n l mixtures ACKNOWLEDGJIENT
The authors are indebted to the Purdue Research Foundation foi, the finanrial assistance which made thir- project po.isible. LITERATURE CITED
0
0.1
0.2 0.3 0.4
0.5
0.6
0.7
AREA O F (001) PEAK, SO. IN. Figure 3.
Kaolinite Working Curve
.llthough the illite emploj ed in this study was a miued-layer mineral, the name of illite was retained to avoid further confusion. The absolute amount of montmorillonite interstratified with the illite, though not determined, is believed to he very small, since the intermediate spacings were very Tyeak. The importance of critically .electing the “standard” rl:t\- minerals for analytical purposes is well illustrated b>- the present study. Though the results given here do not represent those of a true illite, their inclusion ie justified on the basis of the great similarity of the characteristics of the basal plane reflections of illite, hydrous mica, glauconite, etc.
(1) .\Idrich, D. G., Hellman, S . S . , and Jackson, 11.L., Soil S c i . 57,215 (1944). ( 2 ) Rarshad, I., Am. Mineral., 35, 225 (1950). f.3) Bradley, IT.F., J . Am. Chem. Soc., 67, 975 (1946). (4) Brown, G., “X-Ray Identification and Crystal Structures of Clay Minerals,” G. 17.Brindle)., ed., p . 155, London, Taylor and Francis, Ltd., 1951. ( 5 ) Carl. H. F., -4m. Mineral.. 32, 508 (1947). (6) Christ, C. L., Barnes, R. B., and Williams, E. F., -4x.1~. CHEY., 20,789 (1948). (7) Dijke, B. S. ran, Am. Mineral., 34, 74 (1949). (8) Hendricks. S. B., Selson, R. A . , and Alexander, L. T., J . Am. Chem. Soc., 62,1457 (1940). (9) Klug, H. P., .\lexander, L., and Kummer, E., AXAL.C m h r . , 20, 607 (1948). (10) MacEwan, D. M. C., J . Soc. Chern,. Ind.. 65, 298 (1946). (11) RIacEwan, D. 11.C.. Trans. Faraday Soe.. 44, 349 (1948). (12) Marshall, C. E., “Colloid Chemistry of the Silicate Minerals,” Sew York, .\cademic Press, 1949. (13) Sagelschmidt, G., X i n e r n l o g . Mag.. 27, 69 (1944). (14) Socony-Vacuum Laboratories, R e p t . 48-14-5 (1948). (15) n’hiteside. E. P., and Marshall, C. E.. Jlo. .Igr. Exp. Sta., Research Bull. 386 (1944). (1B) TVillis. ;1.L.. Pennington. R. P., and Jackson, RI. L., Soil Sei. SOC.-4m.Proc., 12, 403 (1947).
R E C E I V Efor D review January 11, 1952.
Accepted September 6, 1962. Presented hefore the Eighth Annual Pittsburgh Diffraction Conference, XoT-eiiiber 1950. Journal Paper 594.
Analytical Acetylation Application to Coal Hydrogenation Products C. W. DEWALT, JR.’, AND R . 1. GLESR Coal Research Laboratory, Carnegie I n s t i t u t e of Technology, Pittsburgh, Pa.
T
HE interpretation of the data obtained when standard analytiral methods are applied to crude products from the drgraciation of coal is often difficult. The products obtained dircctly from coal hydrogenation are so complex and so little is linoa-n about their composition that organic group analyses have had a limited application in their characterization. The determination of hydroxyl groups by acetylation, Freed and Wynne’s procedure ( 8 ) , has been used routinely for several years in this laboratory in the study of coal hydrogenation oils, but results have not always been consistent and the cause of the lack of agreement has not been apparent. Therefore, this study was
* Present address, Mellon Institute. Pittsburgh, Pa.
undertaken Tvith a txofold end in viem-: t o obtain reproducible results in the analysis of these complex mixtures and to gain a wider knowledge of the scope of the acetylation reaction, particularly as applied to phenols. Acetylation by acetic anhydride affords a method for determining phenols, as well as primary and secondary alcohols, thiophenols, thioalcohols, and primary and secondary amines. A reactive hydrogen is replaced by an acetyl group in the acetylation of each type, as shopm in the following equations. The analysis for all of these types together, which the procedure under consideration is, may be called the determination of acetylatable hrdi ogen.
1790
ANALYTICAL CHEMISTRY
Functional group analysis is essential to the elucidation of the chemical nature of the organic products derived from coal by mild hydrogenolysis. Use of conventional procedures for organic group analyses is difficult because of the complexity of these materials. The current work was undertaken to evaluate critically t h e factors t h a t affect the results obtained from acetylations w-ith acetic a n h y d r i d e pyridine reagent. A standard procedure has been developed for analytical acetylations of coal hydrogenation products: A sample containing 0.1 to 1.0 meq. of acetylatable hydrogen reacts a t 118" C. for 5 minutes with a weighed 1 ml. of acetic anhydridepyridine reagent; the amount of unused reagent
DETERMINATION OF 4CETYL4TABLE HYDROGEY
Hydroxyl Groups. ALCOHOLS.
+ A c ~ O+ROAc + HOAc
ROH
(Tertiary alcohols may not react.)
(Acetylation) nPhOH
+ A c ~ O+PhO AC + HOAc
Sulfhydryl Groups. THIOALCOHOLS.
+ AczO +RSAC + HOAC
RSH THIOPHENOLS.
+ AcZO +PhSAc + HOAC
(This group has been little investigated.) Amines. PRIMARY. RNH,
+ AcnO +RNHAc + HOAC
SECONDARY. R2NH
+ A c ~ O+RzNAc + H 0 4 c
(Diary1 secondary amines and pyrrole types may not react.) Because the above reactions usually can be carried to completion, they are well suited to analytical purposes. They are catalyzed by pyridine (10, 24), dimethylaniline ( I 6 ) , and quinoline (16). On the basis of quantitative studies with various alcohols the acetylation of alcohols is considered to be a second-order reaction (3). Experiments with 2-tert-butyl-5-methylphenol reported in this paper show that its acetylation is a second-order reaction and it is assumed that the reaction kinetics for phenols in general are the same. The acetylation of phenols is rapid: With pyridine as the catalyst, phenol itself is quantitatively acetylated a t room temperature in 1 minute by an equivalent amount of acetic anhydride even in 0.05% solution ( 2 ) . Of the various types of acetylatable compounds, the phenols predominate in coal hydrogenation oils. Primary and secondary amines appear in much smaller amounts; alcohols may be present and sometimes also compounds Containing sulfhydryl groups. A consideration of the metnods of effecting and measuring the acetylation ( 2 0 ) led to the adoption of the acetic anhydridepyridine acetylation followed by an acid-base (acidimetric) titration of the acetic acid formed. In this method an excess of acetic anhydride in pyridine is used and after the acetylation the unreacted anhydride is hydrolyzed, and the total acid is titrated. The stoichiometry for a sample containing n moles of phenol is outIined in the equations following.
nPhOAc
+ nHOAc + 2Ac20 (1)
(Hydrolysis of Excess Reagent)
+ excess H 2 0
--j
2sHOAc
(2)
(Sum of 1 and 2) nPhOH
(Hindered phenols may not react.)
PhSH
+ ( n + x)AcsO --+ s.4~20
PHENOLS. PhOH
under t h a t from a blank is a measure of the easily acetylatable compounds present-i.e., unhindered phenols, primary amines, and secondary amines. A second determination is made and the reaction time is extended to 1 hour; the decrease, in amount of unused reagent is attributable to the presence of partially hindered phenols. When analytical acetylation is used in conjunction with other methods of organic functional group analysis, such as active hydrogen by Grignard, phenolic groups by titration in ethylenediamine, and basic nitrogen by titration with perchloric acid in glacial acetic acid, a complete distribution of oxygen and nitrogen compounds in coal hydrogenation products may be determined.
+ ( n + r).4c20 + excess H20 + nPhOAc + (n + 2s)HOAc
(3)
The total acid thus formed is then titrated against standard alkali. A blank, in which an aliquot of reagent without sample is hydrolyzed, is then titrated: (Hydrolysis of Blank) (n
+ s)..lc~O + excess HzO +(2n + 2s)HOAc
(4)
The difference between the number of equivalents found in the blank (2% 22) and that found in the sample titration ( n 22) is equal to the number of equivalents of phenol acetylated (n).
+
+
FACTORS IN ACCURACY OF DETERMINATION
In quantitative analytical work it is desirable that all reactions go to completion. Hou-ever, a t present it is not possible to be certain that all reactions go to completion under any practical conditions in the acetylation of coal hydrogenation oils. This is because of the presence of unknown compounds which are acetylated onlly very slowly. In this study the alternative has been to choose reaction conditions which can be duplicated, eo that a given reaction will go to the same percentage completion for any sample. For example, conditions have been chosen t o produce about 50% acetylation of 2,4-di-tert-butylphenol, regardless of whether the sample contains 5 or 100% of this phenol and regardless of the presence of other acetylatable comp0und.i. Different modifications of the technique of Freed and Wynne (8) were employed in the present etudy because of its fiimplirity and rapidity and because it had been used routinely in this laboratory for several years. Comparison is made below between this method and the DeKalt-Glenn procedure, which was developed in this work for the analytical acetylation of hydrogenation products from coal. Resin Formation. Wilson and Hughes ( 2 7 ) noted that the boiling of a 1 M reagent made up from pure dry pyridine and acetic anhydride resulted in formation of a resin containing both oxygen and nitrogen with concomitant loss of acetic anhydride, so that blanks boiled for 6 hours were erratic and as much as 18% low. Malm, Genung, and Williams (IS) found "negligible" loss of titer in their blanks due to resin formation with 0.5 M reagent a t 75" to 80' for 24 hours, but lost on the order of 1%
1791
V O L U M E 24, NO. 11, N O V E M B E R 1 9 5 2 for 0.66 and 0.78 iM reagent under the same conditions. The pyridine they used was carefully fractionated and dried, but the acetic anhydride was a commercial grade assaying 97% or over. Nelson and Markham ( 1 7 ) also observed the formation of a resin when dry pyridine and acetic anhydride were heated together. Wilson and Hughes ( 2 7 ) reported that the addition of water to the pyridine reduced or eliminated resin formation. They also observed that i f water were added to the pyridine before the acetic anhydride, the resin formation was inhibited t,o a greater degree than when the acetic anhydride was added to dry pyridine and followed by the addition of water. Evidently, then, water exerts a specific effect other than that of dilution in inhibiting resin formation in the reagent. Resin formation, when mannitol was present in the boiling reagents, was not mentioned by JYilson and Hughes ( 2 7 ) and their results calculated on unheated blanks showed that it had not occurred. Similarly, in this laborat,ory it was noted that the black coating of resin, which formed on the walls of a flask in which dry 3 M reagent was refluxed for 1 hour over a hot plate, did not, appear when the experiment was repeated with a cyclohexanol sample added to the reagent. Likewise, when 2-isojtropylphenol, which is quantitatively acetylated in 5 minutes, was heat,ed 120 minutes ait'h dry reagent (Table I), there was no significant amount of resin formation. This was confirmed by t,he lack of an increase in the per cent hydroxyl found after longer heating. Addition of eit'her a phenolic or an alcoholic sample, apparently, eliminates resin formation. Therefore, an attempt to increase the accuracy of the determination by treating sample and blank alike-Le., by heating the blank also-introduces error. For this reason unheated blanks were used in this work, and are prescribed in the recommrnded procedure below. Table 1 .
inalytical Acetylation of Phenol and Homologs
Same'"
Reagent Age, days 3
Molarity 3.0 2.0
% Hydroxy1 Foundb Theory 17.94 99.3 13.99 100.5 13 97 100.4 12.71 91.3 12.43 99.7 5.53 99.3 12.51 100.3 12.G1 101.0 12.53 100 5
Av. Deviation,
%
PhenolC 0 0.5 3,4-Xylenold 2 0.17 2,B-Xylenol 1.4 GO 0.50 2,6-Xylenol 1.4 120 1.10 1.4 60 .., 2,3,5-TrimethylphenoIL 3-Pentadeoylphenol/ 2.0 100 0.5 2-IsopropylphenolQ 2.3 1 0.20 2-Isopropylphenolh 3.1 6 ... 2-Ieopropylphenol i 3.1 6 ... 2-IsopropyGS-methyl11.36 100.3 0.15 phenol I 3.0 2 2,4-Di-sec-amylphenoIk 2.0 100 7.42 102.2 1.10 2-Phenylphenol 2.0 2 10.12 101.3 1.10 1-Naphthol 2.0 7 12.06 101.7 0.25 All compounds are Eastman Kodak White Label grade unless otherwise indicated. h Average of duplicate determinations unless otherw-ise indicated. C Redried Mallinckrodt reagent grade. d Recrystallized Eastman Kodak KO.1155. e Single determination on Eastman Kodak S o . P 5961. i Hydrogenated Cardanol (sample 5796) from Irvington Varnish & Insulation Co. Q Koppers Co. sample C50-1768,colorless liquid; S-minute heating at . 1 0 0
110
r.
ut
Single determination with 72-minutr heatinz a t 118' C Single determination with 120-minute heating at 118O r'. j 5-minute heatingat 1 1 S 0 C . i; R t v l i ~ t i l l d Eastman Kodak S o . T z928. h i
In the Freed-T\-ynne and the DeJValt-Glenn procedures resin formation is not, a factor because of the short heating period. Pyridine Purity. There is no experimental evidence in the 1itw:iturc for the presence of any interfering substance in comnirrcial pyridine other than water, or that picolines and other impurities encountered have any effect upon the acetylating power of fwsh reagent other than that of dilution. \\.ilzon and Hughes ( 2 7 )made a study of the effect of impurities in th(5 pyridine and recommendd that i t be purified by an oxidiziiig trcritlnent followed by distillation. However, their published data indicated that the acetylation of mannitol, on which their c.oiic*lu*ionswere based, v a s no less complt~tewhen redistilled
technical pyridine was used without any oxidizing treatment. They stated that up to 15% picoline in the pyridine did not interfere. Ogg, Porter, and Willits (19) found that C.P. pyridine without any purification gave good results in the analyses of oleyl and cyclohexyl alcohols when reagents of appropriate concentration were employed. Water in the pyridine results in the hydrolysis of acetic anhydride after the reagent is made up, thus diluting the reagent without decreasing the blank. The pyridine should, therefore, be as dry as possible. Wilson and Hughes found that a 12to 14-plate column was sufficient to separate the water azeotrope from the pyridine, so that~theproductboilingfrom113'to116.5°C'. contained less than 0.05% m t e r . The use of various grades of pyridine has been reported: the fraction of commercial grade pyridine boiling between 115.5" and 116.5" C. ( 1 3 ) , reagent grade material (13, 19), redistilled reagent grade ( Z l ) , and reagent grade dried by refluxing over barium oxide and boiling above 114' or between 114' and 115" (8,Wd,S4, 26). The latter is used in the Freed-fynne procedure. The pyridine for the present work was prepared by redistilling C.P. material through a 25-plate column and collecting the fraction boiling between 113" and 116" C. For this analysis it is recommended that the pyridine (either commercial or C.P. grade) be dried by distillation using a column of 12 or more theoretical plates. Acetic Anhydride Purity. The literature records no study of acetic anhydride for use in analytical acetylations, and grades varying from commercial ( 1 3 ) to redistilled reagent (21, 24, 26) have been used. Any acetic acid in the anhydride reduces the precision of the analysis, so it should be kept to a minimum. The Freed-Kynne procedure does not stipulate the grade of acetic anhydride, but, in the present work, redistilled reagent grade acetic anhydride \vas employed and is recommended for the DeKalt-Glenn procedure. Concentration of Reagent. Although different workers have used reagents ranging in concentration from 0.5 M ( I S ) t o 10 AI (16), the reagents commonly employed have been from 2.5 to 3.5 V (2 to 3 volumes of pyridine per volume of acetic anhydride, (4,7 , 12, 14, 18-21). More concentrated reagents permit the use of shorter reaction periods, but also decrease the precision of the analysis. In the Freed-TT'ynne procedure both 1.2 and 2 M reagents are used. For use n-ith slox-reacting samples a 3 AI reagent ( 5 volumes of acetic anhydride to 12 of pyridine) measured gravimetrically is recommended in the DeKalt-Glenn procedure. In special cases such as the analyses of some carbohydrates (4,13), an additional factor--solubility of the sample-enters, and a higher proportion of pyridine in the reagent or dilution by an inert, solvent ( 1 5 )may aid in the solution of the sample. Age of Reagent. A 3 W reagent develops a yellow color a few minutes after mixing, and becomes red-brown in a week, but, loses none of its power to acetylate if stored no longer than 1 month in glass-stoppered bottles. The present study has shown that the acetylation rate of 2-tert-butyl-5-methylphenol did not vary noticeably with the age of 2.0, 2.3, and 2.9 JI reagents up to 18 days (Figure l ) , and that the acetylating rate with the 2.9 M reagent was only slightly reduced after 80 days. With a 1.4 M reagent which has st,ood for 120 days, 2,6-xylenol was 91y0 acetylated with 90% excess reagent,, whereas 100% acetylation was obtained after only 60 days of aging (Table I). On the other hand, one m-orker ( 1 9 ) has reported 81 and 85% acetylation of two samples of oleyl alcohol with fresh 1.3 .!!I reagent, but only 59 and 69y0 reaction for the respective samples with 4-day-old rragent. The Freed-JVynne procedure does not, mention the age of the reagent. Hon-ever, in the DeKalt-Glenn procedure it is reconimended that a reagent misture not older than 30 days be employed :ind that storage be in all-glass containers. '
ANALYTICAL CHEMISTRY
1792 Size of Sample. Two factors are involved in the size of the sample: its weight and its hydroxyl content. It is assumed that the amount of acetylating reagent is fixed. When sample weight is fixed, the time required for completioii of the acetylation increases a i t h the per cent hydroxyl content, especially when this approaches equivalence to the acetic anhydride used. From the kinetic equations for a second-order (bimolecular) reaction, the time required for a 99% complete reaction varies as follows: If a molar ratio (hydroxyl to anhydride) of 0.3 requires 5 minutes, 0.7 will require 10 minutes; 0.8, 13 minutes; 0.9, 22 minutes; and 0.95, 30 minutes (see Figure, 2 ) .
hydrates, the water content must be known and taken into consideration as added apparent hi-droxyl when sample size is considered because acetic anhydride is decomposed by water in the presence of pyridine almost as rapidly as by the more reactive phenols. Acid Content of Sample. . h v carboxylic or stronger acids which may be present in the sample muat also be separately determined, as they will be titratrd together with the acetic acid after the hydrolysis. Reaction Temperature. Higher temperatures require shorter reaction periods to produce a given percentage of acetylation. The practical upper limit is the boiling point of the reaction mixture, hut this is not reproducible b o 0 - R e a g e n t s 0.5, 2.0, 2.3 and 2.9 Malar and Up t o 18 Days Old. rause of t'hr variations in composition of the reac* - R e a g e n t 2.9 M a l a r and 2.7 Months Old. tion mixture with thr size of sample taken, as well as Reactions 5 Minutes a t 118.C. with type of sample. The use of heat,ing baths a t __ Km 2.6. IOm3i i t e n moles-' secanda-' 3 7 ° ( 1 4 ) , 6 0 0 t 0 8 0 0 ( 2 d ) , 7 5 0 t 0 8 0( I0S ) , 9O0to1OOo ( I ) , 95" to 100" (271, and 100" ( 1 4 . I 6 ) , as well as a t room teniperaturr (4,I O ! 14, 2 1 ) , has been reported in the literaturr. The Frerd-\\-ynne procedure employs 3, small flame t,o tioil thr reaction mixture. I n the DeKaltGlennprocedurr, a constant-temperature bath, based ;initial cancentration of the phe,,,,,, on the Abderhaldrn principle, employing glacial acetic acid (boiling point 1lS"C.), in the boiler and glycerol x 'amount o f a and b reacted. in the a-ell, is used to maintain a reproducible high t,emperature. Reaction Time. Both a rapid analysis and a coniI plete reaction are desirnble, and both are usually obI I -.e 0 .e tainable since moPt acet,ylations are complete after 5 1 -# minutes at, 118". However, many phenols require Logarithm of b ( a - r ) / a ( b - x ) much over an hour for quantitative acetylation a t Figure 1. Acetylation of 2-tert-Butyl-5-methylphenol 118°C. (see Tahlr I1 j , with the result that assurance Plotted as Second-Order Reaction of complet,e reactioIi wit,h an unknonn sample even after 1 hour is not possible. In order to obtain coiii\Then sample hydroxyl content is fixed-for example, a t 0.3 parative results, therefore, it is necessary to standardize upon or 0.5 J f ratio to acetic anhydride-the time required for coma reproducible period of time for the reaction. pletion of the acetylation increases with decreasing pei cent In the theoretical discussion of reagent concentration and &e of sample, reaction time was considered as the dependent variable, hydroxyl content, especially when this is below about 5%. This constant 0.3 or 0.5 31 ratio of sample to acetic a n h d r i d e and the other conditions were treated so that the time might is commonly stipulated to provide 230 or 100% excess reagent remain essentially constant-i.e., so that the reaction period might "to drive the reaction to completion." be fixed. .?, 5-minute period is used in the DeWalt-Glenn proConstant hydroxyl content is usually preferable to constant cedure because a t 118"C. it accomplished complete acetylation of most phenols and could be accurately duplicated. The Freedsample weight, but neither is ideal. The precision obtainable varies directly with the molar ratio of the sample to acetic anhyWynne procedure employs a 1-minute reaction period. dride if the accurarr of the titration is the limiting factor. Loss of Reagent. Selson and Markham ( 1 7 ) have shown For very careful work where reaction time must be considered that, although acetic acid is kept from evaporation by salt forninas a factor or where samples with both high and lovi hydroxyl percentages are enrountered, the hydroxyl content of the sample may be varied as a function of the per cent hydroxyl rontent. Thus, samples containing as low as 0.5% OH may be analrzrcl L 6W without a large variatloii in reaction time, according to srrondIsorder reaction kinetics, if the number of equivalents of sample is 3 a kept roughly proportional to the square root of the percentage 5* 4of hydroxyl group in the sample (see Figure 3). 8 If manv phenols with different reaction rates are present in a 3mixture, the picture is too complex for a rigorous mathemntiral LL analysis, but the varioust phenols will compete with one another W for the reagent, so that if a large excess of acetic anhydride is zc 2not present, the effects of differences in reaction rates .\?-ill be W magnified. I t i- therefore desirable to fix an upper limit to the Ea I molar ratio of sample to reagent. The dotted line in Figure 3 1 ' ' ' b ' , ' ' ' I b ' ' " shows that the dwrease in reaction time is not great when such an 20 25 PERCENT OH IN SAMPLE upper limit is fixed at 0.3, so that the excess of reagent is not lens L I I I 0 0.2 0.4 0.6 08 10 . than 230%. MOLAR RATIO OF S A M P L E TO ACETIC ANHYDRIDE The Freed-11 J nne procedure suggests a sample containing 1.4 meq. of hydroxyl and the use of 2.4 millimoles of acetic anFigure 2. Effect of Hydroxyl Content of Sample on Time for 99o/c Completion of Reaction hydride. Water-of-Hydration Content of Sample. I n the case of Constant sample weight and 3 M reagent
w
e
Y O b
.
-ticalAcetylation of Coal Hj-drogenation Products (L-sing 2.3 iiimol. of 3.0 M reagent)
Product Kame PHP-Oil
Mg.
401 418
~~~~i~~ ~i~~ a t 118' C., Min. 5
442
Neutral oil
Acetylatable Hydrogen Found
2' 1 71
5
2.15
5
2.23
2 . 18J
437
3
404
65
2.25
422
65
2 . 2 41
641 686
3 5
0.25 0.27
615
J
0.26.
614
5
0.26
351
RO
642
60 ~
~
AT..
lMeq./g.
O'") 0.33
2.18
2
2
4
0.26
0.33
determinations on the PHP-Oil ranged from 2.15 to 2.23 mpq. per gram with an average deviation from the mean of 1.2% (Table V). The potentiometric t,itration of phenols as acids using sodium aminoethoxide in anhydrous ethylenediamine, described by Katz and Glenn ( 1 1 ) ) offers definite advantages for the determination of phenols alone in the coal hydrogenation oil. Although acetylation is not specific for any one type of the various compounds which are present in coal hydrogenation products, it has been found of considerable value in thr chizracterization, analysis, and resolution of these complex materials. Furthermore, it is simple and rapid. Wherever the amount of the individual types of acetylatable compounds is desired, it preferent'ial hydrolysis of the acetylated product may he performed to distinguish between the acetylatable oxygen and nitrogen compounds. By such a technique information may be olitained which is not readily available by other means. Furthermore, when analytical acetylation is used in conjunvtion with other methods of organic functional group analysis, such as active hydrogen by Grignard, phenolic groups bj. titration in pthylenediamine, and basic nitrogen by titration with perchloric avid in glacial acetic acid, a complete distribution of the various oxygen and nitrogen compounds in coal hydrogenation products may be determined. ACKKOWLEDG.MENT
The authors are indebted to the Gulf Research and Development Co. and the Koppere Co. for samples of several of the phenols tested. LITERATURE CITED (1) Adkins, H., Frank, R . L., and Bloom, E. S., J . A m . Chem. SOC., 6 3 , 554 (1941). ( 2 ) Benson, G., and Kitcheii, R. AI., Can. J . Research. 27F, 266 (1949). (3) Callia. V. TT.. Anais assuc. auirn. Brasil. 7 . 178 (1948). (4) Christensen, B. E., and Cla-rk, R. d.,IND:ENG:CHEM.,A s 4 1 . ED.,1 7 , 2 6 5 (1945). (5) Coggeshall, Ii.D., and Glessnel, A. S., J . Am. Chem. Soc , 71, 3150 (1949). (6) Coggeshall, K.D., and Lang, Eleanor, Ibid., 70, 3283 (1948). (7) Delaby, R., and Sabetay, S., BUZZ.SOC. chim. France [ 5 ] , 2, 1716 (1935). (8) Freed, hl., and W y n n e , A. AI,,1x0. ENG.CHEM.,ANAL.ED.,8 , 278 (1936). (9) Howlett, F., and Martin, Elizabeth, J . Teztile Inst., 35, T 1 (1944). (10) Jones, J. S., and Fang, S. C . , ISD.ENG.CHEM.,ANAL.ED.,18, 130 (1946). ( 1 1 ) Kats. hIax, and Glenn, R . A4., ASAL. CHEM., 24, 1157 (1952). (12) Leman, A , , Compt. rend.. 2 1 4 , 8 4 (1942). (13) Malm, C. J., Genung, I.. R.,and TI-illiams, R . F., 11-I).Esc,. C H E X . , A I S A L . ED., 14, 935 (1942). 114) Marks, S . , and Morrell, R , Analyst. 5 6 , 4 2 8 (1931). (15) lleyers, H., "Analyse und Konstitutionsermittlung Organischer Verbindungen," 5th Ed., pp, 328-66, Berlin, Julius Spi'inger, 1931. (16) S a v e s , Y.R., H e l r . CALm. A c t n . 30, 796, 1613 (1947). 117) Selsun, P. A,, and hiarkham, A . E., J . Am. Chem. Soc.. 72,241; (1950). (18) Norniann, W,, and Schildknerht, E., Fettchem. C'mschnir, 40, 194 (1933). 119) Ogg, C. L., Porter, IT.L., and Willits, C. O., IND.ESG.CHEM., ASAL. ED.,17, 394 (1945). (20) Olleman, E. D., AX.AL.CHEM.,2 4 , 1425 (1952). 121) Petersen, J. IT,, Hedberg, K. IT., and Christensen, H. E., IXD. ENG.CHEM., .h"AL. ED.,1 5 , 2 2 5 (1943). ( 2 2 ) Peterson, V. L., and West. E. S.,J . B i d . Chem., 74, 379 (1927). 12:3) Sears, IT. G., and Kitchen, L. J., J . Am. Chem. SOC.,71, 4110 (1949). (24) Stodola, F. H., Mikrochemie, 21, 180 (1937). 125) Verley, A,, and Bolsing, E'.. Bel ., 34, 3354 (1901). (26) W e s t , E. S., Hoagland, C . L., and Curtis, G. H., J . B i d . Chem., 104,627 (1934). (27) Wilson, H. iY., and Hughes, IT. C., J . SOC.Chem. Ind., 58, 74 (1939).
RECEIVED for review June 16, 1932. Accepted August 18, 1932. Presented in part before the Division of Gas a n d Fuel Chemistry a t the 118th C H E M I C ~ LSOCIETY. Chicago, 111. AIeeting of the AMERICAX
