February 1952
I N D U S T R I A L ANI) E N G I N E E R I N G C H E M I S T R Y
electrolytic resistance measurements are more easily made than the measurements described in this paper and, furthermore, may be applied to films attached to electrically conducting substrates, the resistance method would seem to be of greater practical value. The work described in this report, however, has adiled considerable experimental support to the concepts developed several years ago and has markedly improved understanding of the mechmism.by which paint systems protect metallic substrata against corrosion.
329
LITERATURE CITED
(1) Bacon,
R. c., Smith, J. J., and Rugg, F. M., IND. ENQ.CHEM.,
( 2 ) Kittelberger, 40,161 (1948).w,, Ibg., 34, g4s (1942). (3) Kjtblberger, W. w., J . phys. & colloidChem., 53, 392 (1949). (4)Kittelberger, W.W.. and Elm, A. C.. IND.ENQ.C E ~ M 38. . . 696 (1946). ()‘ 876 (1Q47)* RECEIVEDApril 11, 1951. Presented before the Division of Paint, Varnish, 399
and Plastics Chemistry at the 119th Meeting of the AMERICAN CHEMICAL $OCIETY, Boston, Mass.
Heats of Combustion of Some
Nitro Alcohols R. M. CURRIE’, C. 0. BENNETT, AND DYSART E. HOLCOMB2 Purdue University, Lafayette, Znd.
B
ECAUSE the nitro alcohols now being produced commer-
cially are important as starting materials for new syntheses, information about the thermochemical properties of these and similar compounds should be helpful in their present and future utilization. It was the purpose of this study to determine experimentally the heats of combustion of a series of nitro dOohols and to investigate the possibility of correlating these data with some other easily derived property, so that the calculations may be extended t o include other compounds of this type.
ounce copper sheeting and was chrome-plated. The outer surface of the can was highly polished. The calorimeter jacket was a standard EmersonNq. 2BBDanieln acket modified t o provide for stirring of the water in the jacket. he outer surface was insulated with 1 inch of felt. The water in the jacket was heated by making the water itself the conduotor of an electric current in the manner described b y Daniela (3). Cooling 01the jacket water was effected b y the manual addition of cold water.
ir
COMPOUNDS INVESTIGATED
Samples of 2-nitrod-methyl-l-propanol, 2-nitro-2-ethyl-1,3propanediol, 2-nitro-2-propyl- 1,3-propanediol, 2-nitro-2-isoprapyl-1,3-propanediol, 2-nitro-2-methyl-l-phenyl-l-propanol, 2nitro-2-methyl-3-phenyl-l-propanol, and trk(hydroxymethy1) nitromethane were obtained from the Commercial Solvent3 Corp. The samples were further purified by recrystallization. Samples of 3-nitro-2-butanol and 2-nitro-2-methyl-1,3-propanediol were obtained from J. P. Kispersky of the Purdue University Department of Chemiatry. The 3-nitro-2-butanol waa purified by fractionation and the 2-nitro-2-methyl-1,3-propanediol by recrystallization. Time-temperature freezing point curves ( 4 ) were used to estimate the purity of 2-nitro-2-methyl-1-propanol as 99.0 mole %; of 2-nitro-2-ethyl-1,Bpropanediolaa 99.7 mole %; of 2-nitro-2propyl-1,3-propanediol aa 99.5 mole %; of 2-nitro-2-isopropyl-13-propanediol as 99.8 mole %; of 2-nitro-2-methyl-l-phenyl-lpropanol as 99.8 mole %; of 2-nitro-Zmethyl-3-phenyl-1-propan01 as 99.9 mole yo; and of 2-nitro-2-methyl-1,3-propanediolas 99.6 mole %. 3-Nitro-2-butanol and tris(hydroxymethy1) nitromethane were assumed to have purities similar to the above compounds. EXPERIMEi‘(TAL APPARATUS
A semiadiabatic calorimeter system waa used in the experimental determination of the heats of combustion. The apparatus was the same as that described by Holcomb and Dorsey (6)and similar to that perfected by Richards (11) and modified by Daniels (3). Details of the calorimetric system are shown in Figures 1and 2. The bomb used was a standard Parr No. 1101, nickel-chromium alloy ox gen combustion bomb with a double-valve, selfsealing head. J he cylindrical calorimeter can was made from 161
Present address, E. I. du Font de Nemours & Co., Ino.. Buffdo, N. Y.
* Present address, Texas Technological College, Lubbook,Tex.
Figure 1.
Schematic Diagram of Apparatus
A. Constant level control E . Calorimeter stirrer C. Beckman thermometer D. Calorimeter E. Jacket F. Jawket stirrer G. Bomb E. Water-inlet J. Thermal leads ~
~~~
K. Firingleads L. Heater leads
A multiple junction, differential, cop er constantan thermopile connected to a Rubicon “Spotli ht” ga?vanometer w a employed ~ to indicate differences between %e temperature of the jacket water and the temperature of the water in the calorimeter can. Tbe thermopile consisted of two sets of junctions each containing 32 separate junctions and having a resistance of 59 ohms. As shown in Figure 1, one set of junctions was laced in the calorimeter water and one in the jacket water. %e galvanometer wm
INDUSTRIAL AND ENGINEERING CHEMISTRY
330
Vol. 44, No. 2.
etry (15) WLU used to determine the eurrcctiori to be applied to tho experimental data to account ior the tieel gencrateil by the calorimeter stirrer and tho heat gained from or lost to the air surrounding the apparatus. The experimental data were ais@ oorrected for the heat evolved by the iormation of small amounts o i nitric acid. 13xperimental values for the heats of combustion were takcn as the averages o i the results 01 a number of experiments made for each compound, and uncertainty limits were assigned as twice lhe standard dovialions of the averages ( 1 , le). EXI'ERIMENTA L RESULTS
The values determined for the hents of combustion under h o d conditions, a b , are given in Table I. The Washburn corrections (14) have been applied to the values of aEa to obtain AB', the change in iriternal energy ior the reaction with nil m a c l a n k and products in their standard States at 25" C. rind 1 atnrosphere pressure. humming the applicability of tlie perfect ga.s law8 (Y), tlir heats of reaction at constlmt pressure, AH', with all re~ e t a n t sand products in their standard states at 25" C . and 1 atmosphere pressure have hem rslcula,trd from ldre values of AB', the change in internal energy for thc same process. Stsndard heat8 of formstion, AH;, have hem calculated irom the values of A H C and the heats of formation of the products of combustion. The products of combustion were assumed to be gsseoue carbon dioxide, gasoouii nitrogen, and liquid water. Qualitative tests gave no indication o i the presence o i oxides of nitrogm i n the coniljustion gases. T h e standard hen1 o i foormation of liquid water was taken as 68317 kg.-cal. per mole (IS)and the heat o i iorination of gaseous (r:irlmn dioxide as 94.052 kg.-cn,l. per mol', ( I O ) .
Figure 2. Calorimeter Assembly
deflected about 4 iiini. per 0.01" C, tenxperature difference. 'l'emperature changes in the wlorirneter wcre measured by means o i x Beckman-tvpr, differeiltisl, merculy thermometer cdibrated by the w i t i o n a i h m u of Sm&.rds. The enpcriniental s a m p l o ~*,ere ignited by yessing u. ~ u r r e nof t spproximatcly 3 nmperes c~t14 volts through a 10-cm. length of standard Parr iron ium wire for :imeasured time intervnl. The heat evolved by the burning of thc iron fum wire wb8 determined by nieaauiing the length of wire burned arid multiplying this value by the heiit uf oornbustion u i the standard wire per unit lengtlr. A quantity o f heal rras genemted by the electrical energy used in igniting the fuse wire. This was caleulntcd from data O D the current and voltme in the firine line and the time that the current passed through t h i h e wire.
, AND UNCERTAINTIES
~
The linited States I3ureau of Standards sarnplc 39-1 benzoic acid had a hest of cornbustion undcr the bomb conditions equal to 26,429.4 f 2.6 international joules pcr gram mass in vacuo (a). Atomic weights were used as follows ( 8 ) : hydrogen, 1.WW; oxygen, 16.0000; carbon, 12.010; and nitrogen, 14.008. The calorie used in this investigation 18 defined as (8): I calorie equals 4.1833 international joules. The value used for the gas constant, R, WILS 8.3128 + 0.0008 international joules per gram mole, 'K. (9). Uncertainty limits were assigned to the reported values lor heats of combustion BS twice the standard deviation o i the average and, where significant, the standard deviations associated with the accepted constants and other constant factors entering into the reduction of the data were incorporated into the final over-all standard deviation associated with the quantity being evaluated.
I
EXPERIMENTAL PROCEUUR li
&taddnrds WAS used to calibrate the calorimeter system. The conditions specified by the Bureau of Standards WCPB used in the eFperiment8. A sufficient quantity o i benzoic acid w l t ~used to ve approximately a 3.0" C. rise in ealorimeier temperature. %he value of the wate: equivalent of the calorimeter system wm determined by averaging the results of ten calibration experiments. Tho condition? under which the calibration experiments were performed were duplicated as closely DS possible in the investigation of the experimeiital compounds. As the temperature rise for uII experiments WIIS not the same, B series of calibr?.tion experiments giving a temperahe T A B L1.~ SUMMARY OF RESULTSO F H E A P 3 OF COMBUSTION AND FORMATZON' rise of 2" C. was also made, m d No. ot -bE;%t -AE'at -&Host --bePat the average and standard de8Landard Erperi25' C., 25* C.. 260 c., 25' C., viat.ion obtRined for these exCornunund State menta Ka,.csI. /Mole Ka.-Cd. /Mole Kg.-Csl. fixole K~.-Cal./~Mole . . periments were compared with 3.Nitro-Z.butanol Liquid 4 5 9 0 . 5 7 1 1.15 590.21 i 1 . 1 5 5 9 0 . 3 6 i l . 1 5 -83.28-i-1.15 the aversge and standard de2-Nitio-Zmethyl-lviation obtained ior the 3' C. pcDP*"Ol Solid 5 581.80*0.40 585.44-i-0.40 5 8 5 . 5 9 1 0 . 4 0 - 0 S . O S - i - 0 40 2-Nitro-%methylcalibrations. A statistical test 1.3-piopancdioi Solid 4 546.56*0.66 545.15 -i-0.00 546.00i0.66 -138.64 1 0 . 8 6 showed that there W ~ Rno Z-Nitro-Zi.thyl-l.3significant difference in eilher proDanedial Solid 5 701.08i0.32 700.GOi0.32 700.1510.32 -145.25i0.33 Z-Nitro-P-propyl-1,of those two values. On the 3-piolianedml &lid 4 858.97 i 0 . 6 9 858.47 10.88 858.91 i 0 . 6 9 -148.48 -i-0.70 basin of this test the water Z-Nltro-2-isopr?pyl1.3-mopanedmi Solid 5 859.42 1 1 . 0 0 8,68.92 I 1 00 8 6 9 . 3 0 1 1 . 0 0 -148.95I1.00 equivalent WRS assumed not to Z-Nitro-2-methyl-lvary significantly within the 5 1308.79-i- 1.41 1307.96-t 1.41 1 3 0 8 . 7 0 1 1 . 4 1 - 7 5 . 8 8 i 1 . 4 2 phenyl-l-prow,anol Solid limits obtaincd in this invzstiZ-Nitio-2-mothyl-34 1301.57 z t l . 0 5 1300.73 I 1 05 1 3 0 1 ~ 4 7i- 1.05 -83.11 i-1 08 phenyl-1-prowand Solid gation
.~~
A modified form of the ltegnault-I'iaundler equations
Tria(hvdrox~ymotllyl) n1tiomethane
Solid
4
6 1 0 ~ 2 21-0.73
5"9.76&0.73
$09.3z-i-n.73 .-174.32
Limit. ef uncrrWnty have beoa assinned UQ twice the standard deviation8 of the B V ~ Z B Z D R .
io.n
February 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY
331
Equation 1 may be written in a more convenient form
Within the limits of accurac$ of Figure 3, AEband AE” may be assumed the same and Equation 2 may be used to estimate AE”. CONCLUSIONS
The heats of combustion of nine nitro alcohols, including three sets of isomers, have been determined experimentally with an average precision of about 2 parts in 1000. Standard heats of formation have been calculated from the experimental heats of combustion, the heats of combustion of the solid nitro alcohols have been shown to be a linear function of the oxygen balance of the molecules, and an equation has been derived to correlate these two variables. ACKNOWLEDGMENT
The authors wish to express their appreciation to J. P. Kispersky who prepared and purified some of the experimental samples. NOMENCLATURE
A&
= heat of combustion under bomb conditions, kg.-cal. per
mole
AE” = standard change in internal energy a t 25” C., kg.-cal. per
OXYGEN
mole AHo = standard change in enthalpy at 25’ C., k .-cal. per mole AH,” = standard heat of formation at 25’ C. and 1 atmosphere pressure, kg.-cal. per mole M = molecular weight OB = oxygen balance X = number of carbon atoms in the molecule = number of hydrogen atoms in the molecule Y 2 = number of oxygen atoms in the molecule
BALANCE
Figure 3. Heats of Combustion us. Oxygen Balance for the Nitro Alcohols CORRELATION O F HE4TS OF COMBUSTION WITH OXYGEN BALANCE
LITERATURE CITED
Oxygen balance (OB)is defined as the negative of 100 times the weight of external oxygen required for the complete combustion of a unit weight of a compound to carbon dioxide, water, and nitrogen. A plot of the data given in Table I1 for calculated oxygen balances and heats of combustion of the solid nitro alcohols indicates an apparently linear relationship as shown in Figure 3. The points on Figure 3 are numbered to correspond to the nomenclature of Table 11. Heats of combustion of isomers have been averaged before plotting.
TABT,E 11. HEATOF COMBUSTION AND OXYQEN BALANCE FOR NITROALcoHoLs NO.
-
Oxygen 14, Compound Balances Cal./Cr;m 4917.71 - 100,651 127.602 2-Nitro-2-methyl-1-propanol 4037.56 2-Nitro-2-methyl-13-propanedioi - 123.369 4700.48 2-Nitro-2-ethyl-l,3~propanediol 6264.17 - 142.181 6266.96 2-Nitro-2-propyl-13-propanediol 142.181 2-Nitro-2-isopro A-1 3 propanediol -192.619 6704.74 2-Nitro-2-methy~-l-phanyl-l-propanol 6667.74 192.619 2-Nitro-2-methyl-3- henyl-1-propanol 3376.23 -79.407 Tris(hydroxymethy1~nitromethane
-
(1) American Society for Testing Materials, A.S.T.M. Manual on Presatatim of Data, Supplement A, Philadelphia, 1940. (2) Baxter, G.P., etal., J . Ant. Chem. SOC.,63,845 (1941). (3) Daniels, F., Ibid., 38, 1473 (1916). (4) Glasgow, A. R., Streiff, A. J., and Rossini, F. D., J . Research Natl, Bur. Standards, 35, 355 (1945). (5) Holcomb, D. E., and Dorsey, C. L., IND. ENG.CREM.,41, 2788 (1949). (6) Jessup, R. S., J . Research Natl. Bur. Standards, 36,421 (1946). (7)Lewis, G. N., and Randall, M., ”Thermodynamics and the Free Energy of Chemical Substances,” New York, MeGraw-Hill Book Co., 1923. (8) Mueller, E. F., and Rossini, F. D., Am. J . Phys., 12, 1 (1944). (9) Perry, J. H.,“Chemical Engineers’ Handbook,” New York, McGraw-Hill Book Co., 1941. (10) Prosen, E.J., Jessup, R. S., and Rossini, F. D., J . Research Natl. Bur. Standards, 33,447 (1944). (11) Richards, T. W., and Barry, F., J . Am. Chem. SOC.,37, 993 (1915). (12)Rossini, F. D., and Deming, W. E., J . Wash. Acad. Sci., 29, 416 (1939). (13)Wagman, D. D.,et al., J . Research Natl, Bur. Standards, 34, 143 (1945). (14) Washburn, E.W., Ibid., 10,525 (1925). (16) White, W. P., “The Modern Calorimeter,” New York, Reinhold Publishing Corp., 1928. RECEIVED April 30, 1961.
The following equation has been fitted to the data by the method of least squares . A E b = 28.981(0B)
- 1129.8
(1)
where A E b is expressed in calories per gram or kg.-cal. per kg. The average deviation between experimental and calculated values is 0.7% of the experimental value. Whereas the correla tion coefficient for a perfect linear relationship is 1.0000, the correlation coefficient for the present data is 0.9993.
Correction In an article on “Coking of Heavy Residual Oils” [Leo Garwin and B. E. Steinkuhler, IND.ENG. CHEM.,43,2586 (1951)], the broad oven employed in the pilot plant studies was incorrectly described as a “Knowles oven.” It should have been referred to as “the Hughes oven, which is a modification of the LEOGARWIN Knowles oven.”
