Electron spin resonance (e.s.r.) spectra of N O adsorbed on the 4 zeolites Linde 4A, 5A, 13X, and hydrogen mordenite were measured at 77 OK. N o e.s.r. signal was observed for NO on silica gel. By use of expressions for the line shapes of polycrystalline samples, assuming axially symmetric g-tensors, and taking into account also isotropic coupling, values of g , , , g,, and line width were derived by an iterative procedure. From these, the crystal field splitting, A, of the 2pz levels, which become non-degenerate on adsorption, were calculated. By relating A to the interaction of the non-axial components of the quadrupole moment with the corresponding electric field gradients, the non-axial component of the latter is estimated for the surface fields of the zeolites.

The liquid-vapor coexistence curves of very pure xenon have beer1 determined in bombs of vertical lengths 1.2 cnl. and 19 cm. The longer bornb yielded a flattopped coexistence curve, the shorter a Inore rounded curve. The classical van der Waals theory is capable of explaining a large portion of the flat top if effects of gravity are taken into account. Details of the theoretical variation of the width of the flat top with vertical bomb lengths are given. The critical data obtained f?r xenonare Pc = 1.105 grn. /cc., Tc = 16.590 f .00l0C. The danger of contamu~~ation of gases i n the critical region on contact with gasket or packing materials is stressed.

Die Kristallstruktur des Natriumoxohydroxoaluminathydrates Na2[Al2O3(OH)2] · 1,5 H2O – bisher in der Literatur als Na2O · Al2O3 · 2,5 H2O bzw. Na2O · Al2O3 · 3 H2O bezeichnet – wird bestimmt. Die Einkristallröntgenstrukturanalyse (tetragonal, Raumgruppe P‐421m, a = 10,522(1) Å, c = 5,330(1) Å, Z = 4) ergibt eine aus AlO3/2(OH)‐Tetraedern aufgebaute, polymere Schichtstruktur. Die zwischen den Schichten angeordneten Na+‐Ionen bilden mit O2−‐Ionen von AlOAl‐Brücken, AlOH‐Gruppen und von Kristallwasser NaO6‐Oktaeder, die über gemeinsame Flächen zu tetrameren Baugruppen verknüpft sind. 27Al‐ und 23Na‐MAS‐NMR‐Messungen bestätigen die Kristallstrukturanalyse. Die Beziehungen zwischen dem Kristallisationsverhalten der Verbindung und der Konstitution der Aluminatanionen in der entsprechenden Natriumaluminatlösung bzw. in der kristallinen Verbindung werden diskutiert.

Inhaltsiibersicht. Die Kristallstruktur des Nonanatrium-bis(he-xahydroxoa1uminat)-trihydroxid-hexahydratesNa,[Al(OH),],(OH), * 6 H z 0 (4,5Naz0 . A1203 . 13,5H20)bisher in der Literatur als 3 NazO . A1203 . 6Hz0, 4Naz0 * A1203 . I 3 HzO bzw. [3 Na20 . A1,03 6HzO] [xNaOH yHzO] bezeichnetwurde bestimmt. Aus der -Einkristallrontgeastrukturanalyse (triklin, Raumgruppe P1, a = 8,694(1) A , b = 11,344(2) A, c = 11,636(3) A, 01 = 74,29(2)", p = 87,43(2)", y = 70,66(2)", Z = 2) ergibt sich eine Struktur aus monomeren [A1(OH),]3--Aluminatanionen, die uber Na0,-Koordinationsoktaeder untereinander verbunden sind. Die Struktur enthalt weiter zwei Hydroxidionen, die koordinativ nur mit Kristallwasser und OH-Gruppen der [Al(OH),]'--Aluminatanionen in Verbindung stehen, sowie ein drittes, das an drei Na0,-Koordinationsoktaedern beteiligt und auRerdem uber eine Wasserstoffbruckenbindung mit einem Wassermolekul verbunden ist. Die Ergebnisse von 27Al-und "Na-MAS-NMR-Messungen, das thermische Verhalten der Verbindung sowie mogliche Beziehungen zwischen der Struktur der kristallinen Verbindung und den Koordinationsverhaltnissen in der entsprechenden Natriumaluminatlosung werden diskutiert.

Kuclear magnetic resonance has been used to follow the decomposition of aqueous solutions of 2-methyl-A2-oxazoline (0.29 M) a t constant pH values in the range -1 to 14. The decomposition is first order with respect to total oxazoline a t any specific pH, but deviates from the simple reaction of water with the protonated species above pH 5. At neutral pH values this is shown to be partially due to a second reaction involving 2-rnethyl-42-oxazoline and 0-acetylethanolamine which yields N-2-acetoxyethyl bit-2-hydroxyethyl acetamidate. The decrease in rate constant a t pH < 2 is accounted for by variation in the water concentration, which is related to the acidity function. A kinetic expression is derived for the decomposition over the whole pH range studied. The decomposition of the amidate is also discussed.One of the more interesting properties of 2-methyl-A2-oxazoline (I) is its decomposition in aqueous solution to give either 0-acetylethanolamine (IV) or N-acetylethanolamine (111), both the rate of reaction and the product varying with pH. This decon~position has been examined kinetically in neutral and acid solutions by other workers (1, 2 ) and, except for pH < 2, the variation in the rate of decomposition was shown to be dependent on the concentration of the protonated species. Martin and Parcel1 suggested the following mechanism, which involves 2-hydroxy-2-methyloxazolidine (11) as a labile intermediate:Earlier work in these laboratories (3) on the reaction of I in more concentrated solutions showed that this scheme did not account for the results a t pH 7 and 8. Consequently, a study of the decomposition of I in aqueous solutions of pH -1 to 14 was undertaken.Examination of the n.m.r. spectra of I and its known decomposition products, I11 and IV, in this pH range showed that they could be readily differentiated by the field position of the methyl protons. The minimum separation observed in these experiments was a t p H 7 between I and I11 ; however, since I11 is not a significant hydrolysis product of I a t this pH, it did not produce any difficulties. At pH 7 the methyl triplet in I (4) is centered