xov., 1961
SOTES
2105
average pore size. The relationship could be determined by calibration against a primary poresize measurement. The range of 10 to 1000 A. in pore diameter would be involved. If the method were to be used, adsorbent granules should be of the same over-all dimensions to avoid differences in the rate of flow between granules. At least one granule dimension should be greater than 1 millimeter so that the inter-granular flow does not become ratelimiting.
noticed. The epitaxially grown nickel films mostly developed parallel orientations. They were occasionally mixed with a small amount of crystals which were aximuthally rotated by 4 j 0 , ie., they thus had (110) axis parallel to (110) axis of NaC1. { 111] twinned structures of the oxide were observed also. In some cases the patterns due to unknown oxide were predominant. Using 220 rings of either X i 0 or Xi, the dhkl values were evaluated and rings indexed. Table I shows thme values which agree well with a hexagonal structure having a. = 4.61 A., co = 5.61 A. and colao= 1.22. AN OXIDE OF TERVALENT NICKJ3L It is, however, interesting to note that cobaltic oxide (Cos03) has a similar hexagonal structure BY P. S.AGGARWAL AND A. GOSWAMI (UO = 4.64 A., co = 5.75 A., eo/@ = 1.24) with its d National Chemical Laboratorv, Poona-8, Indza values and intensities of rings4 very close to those of Recaved Aprzl 1 1 , 1961 the oxide of nickel mentioned above (Table I). From While iron and cobalt exist in di- and tervalent the consideration of similarities in the properties of states in the oxides of compositions MO, M20; cobalt and nickel compounds and their isomorand M304, the existence of anhydrous Ni203 has phous nature and also of the fact that similar been doubted by many workers. Attempts to pre- chemical compounds have similar structures, it pare this by heating the hydroxide, basic carbonate may be concluded that the observed hexagonal or nit,rate of nickel in air or oxygen resulted in the structure is very likely due to the formation of formation of NiO only.' Cairns and Ott2 prepared the oxide of tervalent nickel (Xi203),as in the from solutions a compound of the composition case of cobaltic oxide (Co207). It may, however, yi~O3.2H20, which decomposed to NiTOs H20 be pointed out here that, in the absence of accurate and finally to KiO, as revealed by X-ray studies. intensity data of Co108 the comparison cannot he No line characteristic of S203was a t all detected. carried out too far. Rooksbya showed, by X-rays, that different oxides ( 4 ) A S.T.N. Card No. 2-0770. of nickel, Hack or otherwise, obtained from various sources consisted only of N O . During electron diffraction studies of evaporated films of nickel, on PRIMARY STEPS I N THE PHOTOLYSIS OF hot rocksalt substrates in uucuo, me observed many METHYL CARBONATE' rings in diffraction patterns, which could not, be BY M. H. J. WIJNEN explained by the presence of Ni and 5 0 alone, but Radzatzon Research Laboratotzes, Mellon Instztutr. Pittsburgh. P a . required the esistence of an oxide having a hesaRecezved M a v 1, 1961 gonal structure. Nickel was evaporated from a nickel filament Investigations of the photolysis of methyl ace(spec. pure, supplied by MIS.Johnson and Matthey tate2.3have shown that the main primary process & Co., London) a t a pressure of about 10-' to produces methoxy radicals according to mm. (obtained by a rotary oil pump) on the cleavCHZCOOCHT + h v --+ CHSCO + CHBO age face of rocksalt crystals kept a t about 400'. After removal of the films from the substrate in the A similar step in the photolysis of methyl carbonate usual way. these were examined in the E D . cam- would lead to CH3OCO and CH30 radicals and possibly to 2CH30 and CO if the CH30C0 radiera by transmission methods. cals would decompose into carbon monoxide and TABLE I" methoxy radicals. This investigation has been a0 = 4 . 6 1 m = 4.64 undertaken to investigate the feasibility of using ci, = 5 . 6 1 co = 5.75 Ni20z co/m = 1 . 2 2 CorOa' co/m = 1 . 2 4 the photolysis of methyl carbonate as a source for Intensity d Intensity hkl d (X-rays) methoxy radicals.
-
3.23 2.80 2.30 2.02 1.77 1.62
vf
..
..
S
m3 S
p 3
101 002 110 200 112 202 21 0 004
3.21 2.87 2.33
.. 1.78 1.63 1.57 1.39
1.40 f 1.11 f ... ... a v, very; f , faint; s, strong; and m, medium.
90 100
100 I
.
.
100 90 -50 90
...
Pat terns thus obtained, consisting of rings and spots, mostly were due to nickel, though sometimes extra rings of X i 0 and the unknown oxide were (1) R. W. Cairns and E. O t t . J . A m . Chem. Soc., 65, 527 (1933). (2) R. W. Cairna and E. Ott, ibid., 66, 534 (1933). (3) H. P. Rooksby, Nature, 162, 304 (1943).
Experimental Since it has been observed4 that methyl carbonate decomposes thermally on quartz, the photolysis was studied at 6 and a t SO" only. The usual photochemical technique hab been applied. A Hanovia Type 73A10 (S-500)medium pressure arc was used to obtain the data a t SO". Constant temperature a t 80" was maintained by an aluminum block furnace. Temperature control a t 6' was obtained by placing the cell in a mater-bath and transmitting the light through a 5 mm. layer of water into the cell. A Hanovia medium pressure arc (Type 16A13) was used as the light source for the experiments at 6". Analyeis of the reaction products (1) ThiR investigation was supported, in part, by the U. S. iltoniic Energy Commission. (2) (a) W. L. Roth and G. K. Rollefson, J . A m Chem. Soc., 64, 490 (1942); (b) P. .4usloos. Can. J . C h e m , 36, 383 (1958). (3) (a) M. H. J. Wijnen, J . Chem. Phys., 27, 710 (1957); (b) 28, 271 (1958): (c) 28, 939 (1958). 4 ' (4) M. H. J. Wijnen, abad., 34, 1465'(1961).
