232 Ind. Eng. Chem. Prod. Res. Dev., Vol. 18, No. 3, 1979
to apply; (3) it covers a wide range of road paving bitumens. Our model is applicable to road asphalts within the penetration range of 20-210. Beyond this range the deviation is unacceptable. Acknowledgment The authors acknowledge the cooperation of KISR for providing all the facilitiesfor this work to be accomplished. Thanks are due to Mr. Marron for his continuous help. Literature Cited
Huet, J., "Etude de la SusceptibilitO Thermique de la Vlscoslte de Bitumens". Centre de Recherches Routhes, Bruxelles, Rapport de Recherches, No. 50, JH, 1958. Knowles, E., McCoy, F., Ind. Eng. Chem., 33(10), 1118 (1943). Kinnaird, R., Proc. Assoc. Asphalf Paving Techno/.,26, 174 (1957). Mack, C., SOC.Chem. Ind., 63, 306 (1939). Mack, C., Proc. Assoc. Asphan Paving Techno/., i 3 , 194 (1942). Pendleton, W., J. Appl. Phys., 14, 170 (1943). Pittman, C., Traxler, R., Physics, 5, 221 (1934). Saal, R., Proc. WorM Petrol. Congr., London, 2, 515 (1933). Thelen, E., J. Appl. Phys., 135 (1937). Wallace, H., Marlln. J. "Asphait Pavement Engineering", Chapter 2, McGraw-HUI, New York, N.Y., 1967.
Received for review October 5, 1978 Accepted April 17, 1979
Hoiberg, A., "Bituminous Materials, Asphaks, Tars and Piches", Vol. I, Chapter 5, Interscience, New York, N.Y., 1964.
Acid-Catalyzed Pyrolysis of Aniline-Formaldehyde Oligomers Frank J. Welgert Contribution No. 2572 from the Central Research and Development Department, E. Wilmington, Delaware 19898
I. du Pont de Nemours and Company,
Aniline-formaldehyde oligomers depolymerize in the presence of Bronsted acids to mononuclear amines. Aniline predominates at low conversions: at higher conversions p-toluidine becomes the major product, as it is in the uncatalyzed reaction. o-Toluidine and 2,4dimethylaniline are minor products and are formed in approximtely equal amounts. Methylenedianiline, but not the higher oligomers, can be hydrogenolyzed to toluidine and aniline in the presence of either acid or supported metal catalysts. The results presented here may be relevant to the Lewis acid promoted depolymerization of coal.
The acid-catalyzed condensation of aniline and formaldehyde to produce methylenedianiline 1, an intermediate useful in both polyamide and polyurethane synthesis, invariably produces minor amounts of higher oligomers with the general structure 2. While for some applications
Table I. Methylenedianiline Catalytic Hydrogenolysisa
catalyst
In = 0
2 n = 31
CI
this mixture is usable, in others any higher oligomers represent an increasingly burdensome yield loss, both from an energy and an environmental standpoint. This work was initiated to find a way of recycling the unwanted oligomers back into 1 production. Previous work had demonstrated that dry distillation of 2 produced aniline and toluidine, but the relative amounts of each and the isomer distribution of the toluidines were not examined (Barclay et al., 1944). Acid-catalyzed reaction of aniline and 2 produces some depolymerization (Ziemek and Raue 1972), but the resulting isomer mixture is not useful for
psi
McCaulay, 1953). Methylenedianiline 1 and the higher oligomers 2 are functionalized diphenylmethanes, and we sought to apply the hydrocarbon technology to these polar systems. Results When dilute solutions of methylenedianiline 1 in benzene are heated under moderate hydrogen pressure at about 25 "C in the presence of selected catalysts shown in Tab e I, varying amounts of mononuclear amines are formed. With solid-acid catalysts the ratio of aniline to toluidine was much greater than 1. With nonpolar hydrogenation catalysts such as group 8 metals on carbon, conversions of 1 were high and the aniline/toluidine ratio approached 1. These initial experiments were performed with room temperature saturated solutions (3 wt %, 1)
2
7
our purpose. Both toluene disproportionation to benzene and xylene and acid-catalyzed xylene isomerization are believed to proceed by diphenylmethane intermediates (Lien and 0019-7890l79l 1218-O232$QI.00/0
H,.,
conv to toluidine
200 500 80 48 H Y faujasite 87% Si0,/13% A1,0, 200 100 11 0 200 NaY f aujasi t e 100
