11016
JOSEPH
L. GREENE,JR.,
AND
HVGHJ. HAGEMEYER, JR.
Vol. 77
indicate a more selective adsorption of the olefinic group. The data for acrylonitrile are interpreted as reaction through the olefinic group, the polar nature of the nitrile group promoting the double bond The dihydro-cyclic intermediate has never been to a more reactive state. The formation of some amrnonium carbonate in isolated, the loss of hydrogen being a spontaneous process under the reaction conditions. The benefi- the pyrolyses of the nitriles over pure alumina, and cial effect of the aromatization-type catalysts re- reported as a by-product in the nitriles-dienes reacported in the earlier workt3 and observed again in t i o n 3 , 1 3 11 can be attributed to a secondary reaction the present study, undoubtedly can be attributed occurring in the alumina surface. The y-alumina to promotion of the dehydrogenation step (Bj in the structure is formed from boehmite by dehydration a t temperatures above 350'. The water thus exover-all process. The mode of action oi the alumina itself must bc pelled hydrolyzes the nitrile in these systems leadbasically different from the aromatization catalysts. ing to the ultimate formation of ammoniacal prodAluminum oxide is known to be an amphoteric sub- ucts. Preliminary work in this Laboratory indistance, having the properties of an acid or base de- cated that this reaction can be minimized by expending on its environment. Under the condition of haustive high vacuum drying of the alumina a t 500' the present work (400-500") the structure is pre- prior to use in the nitriles-dienes reaction. The preferential formation of certain i ~ o t i i e r s ~ ~ ~ ~ ~ ' dominantly the y-alumina structure. The properties of the silica-alumina cracking catalysts ha\-e and the enhanced rates in the heterogeneous reacbeen interpreted on a chemical basis to the exist- tions have been interpreted13 in the light of a Diels ence of aluminum ions ( y-alumina) with the charac- Xlder reaction mechanism. n'assermann and coteristic of a Lewis acid.l' The surface is active to workerslj have reported that the Diels-Alder type electron donors from the gas phase to form com- reaction is susceptible to a general acid catalysis. I n plexes with the Lewis acid. In the present work, the present work, the activity of the alumina in prothe cracking of propionitrile over pure alumina (Ai- moting the rate oi the nitriles-dienes cyclization is 3 ) , and the lower catalytic activity of the alumina best understood as another example of the general containing the basic oxide rather than the acidic acid catalysis of diene addition reactions. Acknowledgment.--The authors wish to thank oxide (i.e., -4-1 and -1-2, respectively) are in accord with some acidic properties of this surface. Corn- Miss Sonja Krause of this Laboratory for the measparison of the relative surface areas when nitriles urements of surface areas. This work was made alone, and butadiene, were passed over the pure possible by grants-in-aid from Research Corporaalumina (Table 11, no. I, 7, S and 5 , respectively) tion of New York and the Research Grants Comindicates t h a t the decrease in area is much smaller mittee of Rensselaer Polytechnic Institute. (13) G. J. Janz and S. C . VvTait, Jr., T H I S J O U R K A L , 76, 6377 (1951J. for the nitriles than the dienes (i.e., the C=N and (14) G. J J a n z a n d TV. J. G. McCullnch, ibid.. 76, 3143 (1954). CH-CH2) groups. This and the teinperaturc rise (16) A . Wasserman, .I. Chcm Soc., (i18 (1042); W. R u h i n . H. Steiner ( I ? ) A. G. Oblad,T. 14.Llillikenand G . A. I\lills,"Ad\~ancesinCatalrsis," Vol. IV, Academic Press, I n c . , N e w York, X . Y . : 1952, p. 231.
[CONTRIBUTION FROM THE
RESEARCH LABORATORIES,
and 4.R7assermann,ibid , 30.16 (1049) TROY,
N. Y.
TENNESSKE B A S T M A S
CO., L)IVISIOX
O P I=&=A-H 1.
Substitution of various acyl groups for a hydrogen atom of an amino group of p-phenylenediamine and also substitution of chlorine atoms for one or two of the hydrogen atoms of the benzene nucleus produce marked differences in the ultraviolet absorption spectrum as compared t o that of p-phenylenediamine (Table I ) . The absorption of the predominantly benzenoid derivatives of the p-phenylenediamine molecules is altered markedly by the introduction of the various acyl groups and the
