ABSTRACTS: October 1973
ABSTRACTS: October 1973
of current literature on the platinum metals and their alloys
The Gold-Nickel-Platinum System
s. m. carmio and j. l. meijering, Z. Metallkunde, 1973, 64, (3), 170–175
Isothermal studies between 812 and 1260°C of the Au-Ni-Pt system enabled the phase diagram to be defined. Solid miscibility in Au-Ni is increased by Pt, and in Au-Pt by Ni additions.
High Pressure and High Field Properties of Nickel-Platinum Alloys near the Critical Concentration for Ferromagnetism
j. beille, d. bloch and e. p. wohlfarth, Phys. Lett., A, 1973, 43A, (3), 207–208
The static magnetic properties and their pressure derivatives were measured for 49.8−58.6% Pt-Ni. Results are in good agreement with the predictions of the homogeneous weak itinerant model and thus characterise these alloys as of the “Invar” type.
Order Hardening in Equiatomic CuPt
r. mitchell, h. g. paris and b. g. lefevre, Metall. Trans., 1973, 4, (3), 833–840
Structure studies of quenched and annealed CuPt showed a fine-domained mottled structure containing all four orientations for samples annealed for short times at 300 and 500°C. Continued annealing led to coarser domains with more ordering. Transformation to order and resultant changes of hardness depend on internal strains caused by cubic to rhombohedral distortion.
Effects of Atomic Ordering on the Curie Temperature of Fe3Pt
t. mizoguchi, m. akimitsu and s. chikazumi, J. Phys. Soc. Japan, 1973, 34, (4), 932–933
The ferromagnetic Curie temperatures were measured for ordered and disordered phases of Fe1−xPtx, where 0.25≤x ≤0.30. The effect of atomic ordering on the Curie temperature is discussed in terms of a pair-interaction model. The Fe-Fe pair interaction is negative when only the nearest neighbour pair interactions are taken into account.
The Chromium-Platinum Constitution Diagram
r. m. waterstrat, Metall. Trans., 1973, 4, (6), 1585–1592
Metallographic, X-ray diffraction and electron microprobe studies of the Cr-Pt system indicated only one intermediate phase, which has Cr3Si (A15) structure. The f.c.c. Pt terminal solid solution extends to 71 at.% Cr at 1530°C with a congruent melting maximum at ∼1790°C. Atomic ordering in this range begins at ∼17 at.% Cr and there is continuous change from Cu3Au to CuAu-type structure as Cr content increases. Eutectics occur at 1530±10°C and 1500±10°C. A syntectic may occur at 1580±10°C. Pt dissolves in the b.c.c. Cr terminal solid solution up to ∼10 at.% Pt at 1500°C but solubility decreases rapidly at lower temperatures.
Absorption of Hydrogen by Palladium/Rhodium Alloys and the Possible Existence of β-Phase Rhodium Hydride
t. c. witherspoon, w. d. mcfall and f. a. lewis, Nature Phys. Sci., 1973, 242, (116, Mar. 19), 44–45
Pressure-composition curves for the absorption of H2 by Pd-Rh alloys suggest an endothermic value of 13000 cal/mol for the heat of formation of β-phase Rh hydride, which it has been suggested elsewhere may be formed at atm at 25°C.
The Destruction of Short-range Order in Au-Pd Alloys by Cold Working
t. e. fine and m. e. nicholson, Scripta Metall., 1973, 7, (4), 383–386
The destruction of short-range order in Au-45 at.% Pd and Au-60 at.% Pd by cold working is non-linear in a manner not yet defined. There is also a limiting value of strain, small for the alloys in question, after which further straining causes negligible reduction in the short-range order.
Diffusion of Hydrogen in Gold-Palladium Alloys
s. maestas and t. b. flanagan, J. Phys. Chem., 1973, 77, (6), 850–854
Diffusion constants for interstitial H2 were determined for a series of randomly substituted f.c.c. Au-Pd alloys at small H2 contents, where the dissolved gas behaves ideally. 20 at.% Au has little effect on the diffusion constant but for Au content greater than this, values of D decline logarithmically with Au content to D = 7.4 × 10−10 cm2/sec for 55.7 at.% Au-Pd.
Magnetic Susceptibility and Equilibrium Diagram of PdHn
h. frieske and e. wicke, Ber. Bunsenges. Phys. Chem., 1973, 77, (1), 48–52
To establish the limits and of the PdHn two-phase region, measurements of magnetic susceptibility χ as a function of H2 content in Pd were made at 20−300°C, PH2 up to 140 atm for 0 ≤n ≤0.8, using Pd wire and foil. and could then be determined by extrapolation. The critical point of the Pd-H system was then redetermined with good precision as Tc=291±2°C, nc=0.250±0.005 mol H/mol Pd, pc=19.7±0.2 atm H2. Studies using Pd black agreed for Tc and pc but nc was 0.260±0.005 mol H/mol Pd.
Statistical Mechanics of a Three-component System: Pd-B-H
r. mehlmann, h. husemann and h. brodowsky, Ber. Bunsenges. Phys. Chem., 1973, 77, (1), 36–41
Statistical mechanics of the Pd-H and Pd-B systems are extended to the Pd-B-H system. Absorption of H2 on Pd-B alloys can then be analysed in terms of the thermodynamics of the system and the energies between the atoms.
The Eutectoid Region of the Ti-Pd System
j. c. williams, h. i. aaronson and b. s. hickman, Metall. Trans., 1973, 4, (4), 1181–1183
Previous studies of the eutectoid region of the Ti-Pd system are in conflict. This study resolves the difficulty, establishes a new phase diagram of the region and points to transmission electron microscopy as the principal technique for phase diagram determination.
The Chromium-Iridium Constitution Diagram
r. m. waterstrat and r. c. manuszewski, J. Less-common Metals, 1973, 32, (1), 79–89
Metallographic, X-ray diffraction and electron microphobe studies of the Cr-Ir system show that it contains two intermediate phases, a β phase with Cr3Si(A15)-type structure stable from ∼73 to 82 at.% Cr, and a e phase with h.c.p. structure stable at 30–68 at.% Cr. The f.c.c. Ir terminal solid solution can dissolve ∼28 at.% Cr and atomic ordering occurs in it from 16 at.% Cr to form a Cu3Au structure up to the limit of solid solubility. Ir dissolves in the b.c.c. Cr terminal solid solution to ∼12 at.% Ir at 1680°C but less at lower temperatures. Peritectic reactions occur at 1750±10°C and 2200±50°C. A eutectic occurs at 1680±10°C.
Metastable Phases in Ti-Ru Alloys Rich in Titanium
l. n. guseva, n. g. boriskina and l. k. dolinskaya, Izv. Akad. Nauk S.S.S.R., Metally, 1973, (3), 215–217
Studies of the structure and hardness of cast and tempered β-phase alloys showed that α′, α″ and ω metastable phases occur during tempering. Critical composition for ω-phase formation is 3.8–8 at.% Ru, corresponding to an electron concentration of 4.16–4.32 electrons/atom. The ∼9% difference in size between Ti and Ru atoms appears to be critical for formation of the martensitic α″-phase.
Electrical Resistivity of Chromium-Ruthenium Alloys
t. f. de young, s. arajs and e. e. anderson, J. Less-common Metals, 1973, 32, (1), 165–169
Resistivity-temperature curves for 6.6, 8.3, 10.1, 11.4, and 14.0 at.% Ru-Cr alloys possess large anomalies when antiferromagnetism appears. Néel temperatures TN for these alloys and for other Cr-Ru alloys studied earlier were calculated and rise rapidly up to the 3 at.% Cr level, then plateau and then decrease with increasing Ru content. This behaviour and the resistivity-temperature curves are interpreted as due to the electron and hole Fermi surfaces of Cr and other changes as electron concentration increases.
Phase Equilibria in the System Zirconium-Vanadium-Ruthenium
m. m. akhverdyan, m. v. raevskaya, v. v. burnasheva, e. i. gladyshevskii and e. m. sokolovskaya, Vest. Moskov. Univ., Ser. II, Khim., 1973, 14, (2), 182–186
X-ray microscopic and hardness studies of the Zr-V-Ru system at 900−1500°C were carried out on annealed, quenched and as-cast alloys. An isothermal cross-section was obtained for the alloy annealed at 900°C.
Reactions of Platinum Metals with Carbides of Groups IV and V of the Periodic System of the Elements during Sintering and Melting
e. raub and g. falkenburg, Metall, 1973, 27, (7), 669–679
Pt, Ru, Rh, and Ir were reacted with carbides of Ta, Ti and V. Structures of the materials produced by sintering and melting were tabulated.
The Stability of K2[Pt(CN)4]Cl0·3.xH2O in Wet and Dry Atmosphere
d. cahen, Solid State Commun., 1973, 12, (11), 1091–1094
The behaviour of the one-dimensional electrical conductor K2[Pt(CN)4]Cl0·3.xH2O was studied at several temperatures in both wet and dry atmospheres. The material can be considered as a series of hydrates with x = 2.5–3. Effect of variation of x on physical properties is discussed.
Reaction of 14C-labelled Platinum Ethylenediamine Dichloride with Nucleic Acid Constituents
a. b. robins, Chem.-Biol. Interactions, 1973, 6, (1), 35–45
Reactions of Pt(en)Cl2 in 0.1 M NaClO4 with adenine, guanine, cytosine, and their nucleosides and nucleotides were followed by radioactive labelling with 14C. Guanine derivatives reacted the most rapidly, notably guanosine. Probably more than one site on these compounds is available for reaction with Pt(en)Cl2.
Effect of cis -Dichlorodiammineplatinum(II) on Escherichia Coli B. Role of fil, exr and hcr Markers
j. drobnik, m. urbanokova and a. krekulova, Mutat. Res., 1973, 17, (1), 13–20
Colony forming ability (C.F.A.) of Escherichia Coli B mutated at fil, exr and hcr loci was unaffected by cis -Pt(NH3)2Cl2 even at concentrations that reduce the C.F.A. of the parent strain by five orders of magnitude. Sensitivity to the Pt compound appears to depend on the pleiotypic response of the cells.
Suppression of Lymphocyte Blastogenesis in Man Following cis -Platinous Diaminodichloride Administration
a. khan and j. m. hill, Proc. Soc. Exp. Biol. Med., 1973, 142, (1), 324–326
Administration of 1–4 mg phytohemaglutinin/kg to subjects receiving cis -Pt(NH3)2Cl2 for various tumours significantly inhibited lumphocyte blastogenesis for 18–72 h. Single dose administration produced more inhibition than divided doses.
Thermal Expansion of Corundum Structure Rh2O3
l. j. eckert and r. c. bradt, Mater. Res. Bull., 1973, 8, (4), 375–378
X-ray diffraction measurements of the directional thermal expansion coefficients αa and αc of corundum structure Rh2O3 at 0−850°C showed that it has lower thermal expansion and less anisotropy than Al2O3. αa = 5.350 × 10−6 + 1.281 × 10−9T−1.133 × 10−14T2/°C and αc = 5.246 × 10−6 + 6.369 × 10−9T—7.480 × 10−14T2/°C.
Adsorptive and Catalytic Properties of Platinum Microcrystals Deposited on Inert Supports
v. s. bagotskii, l. s. kanevskii and v. s. palanker, Electrochim. Acta, 1973, 18, (7), 473–483
The electrochemical and catalytic properties of dispersed Pt catalysts on smooth, inert supports, i.e. Au or pyrographite, were studied. H2 adsorption on platinised pyrographite is markedly greater than that on plain pyrographite and the adsorption energy for deposited Pt differs from that of smooth Pt. The specific catalytic activity of deposited Pt in H2 evolution and ionisation, too, is greater than that of smooth Pt. This effect is most pronounced for small coverages of the support surface with Pt.
The Anodic Oxidation of Hydrogen on Platinised Tungsten Oxides. II. Mechanism of H2 Oxidation on Platinised WO3 Electrodes
b. s. hobbs and a. c. c. tseung, J. Electrochem. Soc., 1973, 120, (6), 766–769
Electrochemical measurements of the anodic oxidation of H2 on a platinised WO3 electrode show that this support material takes an active part in the overall electrode reaction which proceeds by the formation and oxidation of hydrogen tungsten bronzes, viz:
WO3 + x Pt − H→HxWO3 + Pt HxWO3→WO3 + xe− + xH+
ELECTRODEPOSITION AND SURFACE COATINGS
Generative and Stabilising Processes in Tin-Palladium Sols and Palladium Sol Sensitisers
r. l. cohen and k. w. west, J. Electrochem. Soc., 1973, 120, (4), 502–508
Studies of sol systems produced by reduction of solvated Pd by Sn2+ show that the reduction is initiated by the formation of a polynuclear autoreductive Sn-Pd complex. Sol particles have Sn-Pd alloy cores with a stabilising layer of Sn2+ ions. The data are applied to commercial Pd sol systems for sensitising insulating surfaces for electroless plating. Other studies concerned the chemistry of the sensitising layer and the sol sedimentation rate.
Mechanism of Activation of Polymer Surfaces by Mixed Stannous Chloride/Palladium Chloride Catalysts
a. rantell and a. holtzman, Trans. Inst. Metal Finish., 1973, 51, (2), 62–68
Studies by nephelometry and electron diffraction of the nature of SnCl2-PdCl2 catalysts used for activation of etched ABS surfaces before electroless Ni or Cu deposition showed no colloidal Pd. The active catalytic component is thought to be a complex Sn(II)-Pd(II) chloride. Activation involves hydrolysis of an adsorbed chloride complex within the ABS surface. NH4HF2 accelerator presumably then causes a surface redox reaction to form active Pd nuclei. Immersion times in all pretreatment solutions, including rinses, directly affect the induction period.
Catalyst Cuts Costs by Reducing Temperature for Incinerating Plant Odours
r. a. searles, Process Engng., 1973, (Feb), 100–102 Honeycat ceramic honeycomb catalysts developed by Johnson Matthey allow incineration of unpleasant process odours to take place at much lower temperatures than with thermal incineration.
Hydrogenation of Aromatic Hydrocarbons of 140−240°C Fractions on Platinum-Rhenium Catalyst
a. s. zhurba, yu. e. smol’nik, kh. m. minachev, m. a. ryashentseva, r. v. katrush and a. d. martynyuk, Khim. Tekhnol., Topliv Masel, 1973, (6), 7–9
Optimum conditions are given for hydrogenation of a wide range of straight-run fractions, evaporated at 140−204°C, over a Pt-Re catalyst. Analogous conversion on Pt/Al2O3 occurs at 40 atm, 300°C.
Application of Thermal Desorption Methods in Studies of Catalysis. I. Chemisorption of Carbon Monoxide on Platinum. II. The Oxidation of Carbon Monoxide on Platinum
w. l. winterbottom, Surface Sci., 1973, 36, (1), 195–204, 205–224
The desorption of CO from a polycrystalline Pt surface is characterised in terms of first order processes from essentially four surface states. A two-site adsorption process is proposed on the basis of a sequential adsorption pattern and distinguishable reactivity differences.
Aromatisation of n -Nonane in the Presence of Platinum/Alumina Catalyst
v. f. il’in and yu. n. usov, Neftekhimiya, 1973, 13, (3), 387–394
Acidic 0.5 wt.% Pt/Al2O3 catalysed aromatisation of n -nonane at atmospheric pressure in a stream of H2 at 310−490°C to form C9 cyclic pentanes (n -butylcyclopentane,1-methyl-2-n -propylcyclopentane, 1,2-diethylcyclopentane). These cyclanes are converted to aromatic C9 hydrocarbons by dehydroisomerisation and C6-dehydrocyclisation. Isomerisation of C9 alkylbenzenes in conditions for aromatisation of n -nonane does not play a significant role in forming isomeric aromatic hydrocarbons.
Efficiency of Pt-Aluminosilicate Catalysts in H2O2 Decomposition
t. g. martynyuk, t. a. pospelova, v. i. shekhobalova and n. i. kobozev, Zh. Fiz.Khim., 1973, 47, (5), 1168–1171
Activity was related to Pt content for two series of Pt/SiO2–Al2O3 produced by impregnation and by adsorption. Activity of Pt/SiO2–Al2O3 was compared with that of Pt/CaY zeolite with the same Pt content. Activation energy of each was 10–11 kcal/mole.
Effect of the State of Reduction on the Properties of Platinum Adsorption Catalysts
z. v. luk’yanova, v. i. shekhobalova and n. i kobozev, Zh. Fiz. Kkim., 1973, 47, (4), 908–910
0.7−70 wt.% Pt/aerosil catalysts were produced by low temperature reduction with NaBH4 in solution. Tests of their activity for H2O2 decomposition were undertaken, and also measurements of specific activity and activation energy for catalysts reduced with NaBH4 and with electrolytic H2 at 300°C. H2O2 decomposition is first order with respect to method of catalyst preparation, metal loading and H2O2 concentration. Activity differs between the methods of reduction by 3–5 times.
Rearrangement of Cyclic Amines Catalysed by Palladium
n. yoshimura, i. moritani, t. shimamura and s.-i. murahashi, J. Chem. Soc., Chem. Commun., 1973, (9), 307–308
Pd suspended in pyrrolidone catalysed the rearrangement of cyclic amines to form N -substituted cyclic amines, and of heterocyclic amines to N -formyl cyclic amines.
Catalytic Dehydrogenation of Coal: Part 7. The Effect of Some Catalyst Variables
l. reggel, i. wender and r. raymond, Fuel, 1973, 52, (3), 162–163
The yield of H2 during the catalytic dehydrogenation of vitrinite in the presence of phenanthridine as vehicle is most strongly influenced by which catalytic metal is chosen rather than its concentration or the nature of the support. Of a large variety of catalysts evaluated, Pd gave the highest yield.
Arylation of Olefin with Iodobenzene Catalysed by Palladium
k. mori, t. mizoroki and a. ozaki, Bull. Chem. Soc. Japan, 1973, 46, (5), 1505–1508
Arylation of propylene, ethylene, styrene and methyl acrylate with iodobenzene is catalysed by metallic Pd in MeOH to give respectively methylstyrene, styrene, t -stilbene and methyl cinnamate. The yields and selectivities are increased significantly by the addition of excess potassium acetate as an acceptor of the hydriodic acid formed. The reaction is discussed in terms of the oxidative addition of iodobenzene to a Pd complex of low oxidation state.
Relation of the Direction of Hydrogenolysis of Methylcyclopentane on Pd-Al2O3 to the Electron Distribution in the Molecule
i. i. levitskii, kh. m. minachev and a. m. boganov, Izv. Akad. Nauk S.S.S.R., Ser. Khim., 1973, (4), 762–767
Tests on the hydrogenolysis of methylcyclopentane showed that when the pressure was increased from 10 to 40–50 atm using Pt/Al2O3 the ratios of n -C6H14 to 2-methylpentane, of n -C6H14 to 3-methylpentane, and of 3-methyl-pentane to 2-methylpentane in the products all increased but using Pd/Al2O3 the ratios decreased. These results confirm that the process is connected with the charge on the C atom and the charge of the catalyst metal atom.
Catalysis in Adsorbed Mixed Layers of d Elements Based on Platinum Metals with Variable Charging of the Surface
i. a. zubovich, Zh. Fiz. Khim., 1973, 47, (5), 1081–1094
Data on the activity of adsorption catalysts consisting of Pt and Pd with various additions of Ag, Cu, Re, Os, Ru, Ir, Rh, Pd in liquid phase hydrogenations, reductions, and H2O2 decomposition, and also on the magnetic susceptibility of these systems enabled conclusions to be drawn on the possible formation of surface atomic structures and on electron-atom effects and microelectronics in heterogeneous catalysis.
Liquid Phase Hydrogenation of Heptene-1 on Palladium-Rhodium Catalyst
l. a. sokolova, a. d. dembitskii, n. m. popova, d. v. sokol’skii and m. i. goryaev, Neftekhimiya, 1973, 13, (2), 174–179
Liquid phase hydrogenation of heptene-1 on 5% Pd-Rh/Al2O3 is accompanied by double bond migration to form stereoisomers. The rate of H2 absorption during this process is higher than on simple Pd or Rh catalysts and alters in direct relation to the content of adsorbed H2.
Dealkylation of Xylenes by Reaction with Water Vapour on Rhodium Catalyst
g. l. rabinovich, l. m. treiser, g. n. maslyanskii and a. a. tokareva, Neftekhimiya, 1973, 13, (3), 415–421
Xylenes are dealkylated over Rh at 400–480°C with H2O vapour to form C6H6 and toluene. A secondary reaction is cleavage of the aromatic ring. Increasing the temperature during dealkylation of o -xylene does not affect the C6H6: toluene ratio but the ratio is increased during dealkylation of m -xylene.
Hydrogenation of Ethylene and Benzene on Rhodium/Zeolite Types A, X and Y
z. v. gryaznov, e. v. kolodieva, v. p. paranosenkov, g. v. tsitsishvili and a. yu. krupennikova, Neftekhimiya, 1973, 13, (3), 374–381
Zeolite supports for Rh are not inert, since the orders of activity are X>Y>A for C2H4 hydrogenation and Y>X>A for C6H6 hydrogenation both in pulsed and steady conditions. Adsorption of H2O affects the activity of the zeolites, depending on the sizes of the molecules to be reduced, the types of zeolite, the dislocations of the active centres in these structures, and the way the H2O is introduced into the zeolites.
The Catalytic Reduction of Nitric Oxide over a Supported Ruthenium Catalyst
k. c. taylor and r. l. klimisch, Abstr. Papers, 165th Natl. Mtg., Am. Chem. Soc., 1973, (Apr.), COLL 27
The reduction of NO by CO and H2 over a supported Ru catalyst was studied using a feed stream resembling automobile exhaust gases. The effects of space velocity and reactant concentration on the NH3: N2 product distribution and also the effect of these parameters on NO removal were investigated. The pertinent chemical reactions in this system and the limitations imposed by an exhaust gas feed stream are discussed.
Addition Reactions of Butadiene Catalysed by Palladium Complexes
j. tsuji, Accounts Chem. Res., 1973, 6, (1), 8–15
Studies on oligomerisation and telomerisation of butadiene using Pd catalysts show that such reactions are unique and useful. Pd complexes catalyse cocyclisation of butadiene with hetero-polar double bonds and telomerisation with nucleophiles. These reactions cannot be achieved with other transition metal complexes (76 references).
Palladium(II)-catalysed Exchange and Isomerisation Reactions
p. m. henry, Accounts Chem Res., 1973, 6, (1), 16–24
Expansion of homogeneous catalysis using Pd complexes has led to studies of reaction mechanisms, including those of vinyl ester exchange with radioactive chloride, allylic trifluoacetate exchange with chloride, vinyl chloride exchange with acetate, acid-catalysed allylic exchange, and cis-trans isomerisation (51 references).
Isomerisation of Heptene-1 in the Presence of π-Complexes of Palladium Chloride
yu. m. zhorov, g. v. demidovich and g. m. panchenkov, Neftekhimiya, 1973, 13, (3), 395–400
Studies of homogeneous isomerisation of heptene-1 over PdCl2 or π-complexes of PdCl2 indicated double bond transfer to heptene-2 or -3 but no direct cis-trans isomerisation. The most active catalysts for this reaction are complexes containing olefin ligands. The formation of trans olefins during exchange of π-complex ligands includes transfer of H from the first to the third C atom.
Palladium(II)-catalysed Exchange and Isomerisation Reactions. VIII. Isomerisation of Vinylic Halides in Acetic Acid Catalysed by Palladium(II) Chloride
p. m. henry, J. Org. Chem., 1973, 38, (6), 1140–1144
Pd(II)-catalysed isomerisation of cis- and trans -1-chloropropene obeys a three-term rate expression, the terms of which are analysed. Isomerisation of 1-cromopropene obeys mainly a two-term expression.
Oxidation of Olefins by Palladium(II). VI. Ethylene Oxidation by Palladium(II) Acetate in Acetic Acid Promoted by Various Oxidants
p. m. henry, J. Org. Chem., 1973, 38, (9), 1681–1684
Like CuCl2 and this study of Pd(II) salts in CH3COOH as oxidants of C2H4 showed that K2Cr2O7, NaNO2, CuBr2, MnO2, Pb(OAc)4, Tl(OAc)3, TlCl3, and HAuCl4 act as promoters to increase the oxidation rate and change the product from vinyl acetate to 1,2-disubstituted ethanes. Ethylidene diacetate was also formed when the three latter promoters were used. Other substances tested showed no promoting activity.
Hydrogenation of Diene Hydrocarbons in the Presence of Chlorodimethylsulphoxide Complexes of Palladium
l. kh. freidlin, yu. a. kopyttsev and n. m. nazarova, Neftekhimiya, 1973, 13, (3), 369–373
Chlorodimethylsulphoxide complexes of Pd are highly active in catalysing hydrogenation of dienes. The reaction is zero order with respect to dienes. It is selective, for no alkanes are formed during the addition of the first molecule of H2. The hydrogenation forms non-equilibrium mixtures of olefins, predominantly trans -form β-isomers. Dienes are co-ordinated to Pd complexes during reduction mainly in the trans conformation.
Investigation of the Homogeneous Reaction of Hydrogen Transfer from Pentanol-2 to Cyclohexanone, Catalysed by Tristriphenyl-chlororhodium in the Presence of Alkali
l. kh. freidlin, v. z. sharf, v. n. krutii and g. t. prokopenko, Kinet. Kataliz, 1973, 14, (3), 601–603
Studies of H transfer from pentanol-2 to cyclohexanone and of the hydrogenation of this by H2 in the presence of RhCl(PPh3)3 catalyst and alkali show that the reaction proceeds through a number of stages.
Activation of Hydrogen by Bridged Transition Metal Carboxylates. Rhodium(II) Acetate Catalysed Hydrogenation of Olefins
b. c. y. hui, w. k. teo and g. l. rempel, Inorg. Chem., 1973, 12, (4), 757–762
Rh2(OOC.CH3)4 is an efficient and selective catalyst for hydrogenation of terminal olefins in various solvents, e.g. dec-1-ene in N,N′-dimethylformanide. The initial step in the hydrogenation involves activation of H at only one metal centre in the dimeric catalyst. The H activation involving heterolytic splitting of H2 leads to formation of the intermediate HRh2 (OOC.CH3)3, which then reacts with the olefinic substrate. Olefin insertion into the metalhydride bond followed by proton attack on the intermediate metal alkyl completes the catalytic cycle.
Catalysis by Metal Complexes. IX. Catalytic Properties of Tris(diphenylphosphine) chlororhodium(I)
p. svoboda, m. Čapka and j. hetflejŠ, Coll. Czech. Chem. Commun., 973, 38, (4), 1235–1241
The catalytic activity of tris(diphenylphosphine) chlororhodium(I) in hydrosilylation, hydrogenation and hydroformylation was studied and compared with its analogue, tris(triphenyl-phosphine)chlororhodium(I). The diphenyl-phosphine complex is effective as a hydrosilylation catalyst but is a relatively poor hydrogenation catalyst; hydroformylation proceeds in its presence under comparatively mild conditions.
In Situ High-pressure, High-temperature Spectrophotometric Studies of the Chloro-carbonylbis (triphenylphosphine)rhodium (I) Hydroformylation Catalyst Activated by Hydroperoxides
h. b. tinker and d. e. morris, J. Organometal. Chem., 1973, 52, (2), C55–C75
The rate of hydroformylation of olefins catalysed by RhClCO(Ph3P)2 is accelerated by the addition of a small amount of cyclohexenylhydroperoxide which converts this mono-carbonyl complex into cis -RhCl(CO)2Ph3P, which is a highly active hydroformylation and isomerisation catalyst for olefins.
Asymmetric Olefins Hydroformylation. III. Asymmetric Induction by Rhodium Complexes Using (—)−2,3-0-Isopropylidene-2, 3-dihydroxy-1,4-bis(diphenylphosphino) butane as Chiral Ligand
c. salomon, g. consiglio, c. botteghi and p. pino, Chimia, 1973, 27, (4), 215–217
The asymmetric hydroformylation of aromatic olefins at atmospheric pressure and low temperature is promoted by RhH(CO)(Ph3P)3 in the presence of (−)-2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino) butane. In the case of styrene asymmetric induction reaches 25%.
Asymmetric Hydrosilation of Ketones Catalysed by a Chiral Cationic Rhodium Complex
k. yamamoto, t. hayashi and m. kumada, J. Organometal. Chem., 1973, 54, C45–C47
The catalytic behaviour of a cationic Rh complex, with an optically active phosphine as ligand, for the asymmetric hydrosilation of alkyl phenyl ketones is discussed.
Homogeneous Dehydrogenation of Formic Acid by Complex Compounds of Monovalent Iridium
e. n. yurchenko, Kinet. Kataliz, 1973, 14, (2), 515–518
Studies of dehydrogenation of HCOOH in the presence of IrClCO(PPh3)2 at 1 atm, 20−50°C showed that the minimum permissible ratio of initial K3IrCl6 to PPh3 in the complex is 1 : 7. The reaction is first order with respect to the initial complex and the acid. Dehydrogenation is preceded by formation of IrCO(PPh3)2HCOO.
Hydrido Transition-metal Cluster Complexes
h. d. kaesz, Chem. Br., 1973, 9, (8), 344–352
These complexes, among which those of Ru and Os are important, may provide an important link between the study of soluble molecular complexes (homogeneous catalysis) and of solid state and surface phenomena (heterogeneous catalysis).
Direct Biological Fuel Cell
j. f. henry and j. h. fishman, Extended Abstr., 143rd Mtg., Electrochem. Soc., 1973, 73–1, (May), 723–724, abstr. 295
Au-Pd alloys are used for the electrodes of a direct fuel cell consuming O2 and fuels available in blood. Details of electrode construction and cell performance parameters are given.
ELECTRICAL AND ELECTRONIC ENGINEERING
Platinum-Rhenium-Tungsten Alloy Thin Film Resistors
c. y. ang, r. f. bailey and j. r. ogren, Extended Abstr., 143rd Mtg. Electrochem. Soc., 1973, 73–1, 541–542, abstr. 221
Ternary alloy films were prepared by RF sputtering using a target 11% Re−20% W–Pt formed by powder metallurgy techniques. The sputtering procedure, composition analysis, thickness measurements, and determination of electrical resistivity as a function of film thickness and temperature are described.
Stability of Thick-film Resistors under High Electromagnetic Stress
p. w. polinski, Solid State Technol., 1973, 16, (5), 31–35, 58
Tests on RuO2 crystal, Ru resinate and Pd-Ag thick-film resistor compositions under high electromagnetic stress of several kV/in showed wide variations in conductivity. The conduction mechanism in the stable RuO2 composition for a total fired resistor thickness of 13–15 μm forms very close to the Al2O3 substrate in a microlayer a few μm thick. The conduction layer is thicker for lower resistivity compositions where the RuO2 content is higher but it is still close to the surface of the substrate. This formation is probably due to the dense RuO2 crystals settling out while the composition is held at the high peak firing temperature.
Measurement of Temperature of the Glass Mass in a Furnace with a Cooled Metallic Cladding
a. g. gurkov, v. i. pokolenko and v. n. ruslov, Steklo Keram., 1973, (5), 11–12
Pt thermocouples with a cooled metallic cladding to protect them are used to compare the temperatures at various points in a furnace containing molten glass.
The Departure of IPTS-68 from Thermodynamic Temperatures between 725°C and 1064.43°C
t. j. quinn, t. r. d. chandler and m. v. chattle, Metrologia, 1973, 9, (1), 44–46
The departure of IPTS-68 from thermodynamic temperatures at 725−1064.43°C is discussed with particular reference to the Pt:13%Rh-Pt thermocouple.
Contribution to the Study of the Effect of Pressure on the Platinum : Rhodium-Platinum Thermocouple
m. lallemand, j. brielles, d. vidal and p. malbrunot, J. Phys. D, 1973, 6, (9), 1052–1057
Variations of the melting points of Au and Ag with pressure were measured with a Pt:10% Rh-Pt thermocouple under hydrostatic conditions. Results indicate a decrease of thermocouple e.m.f. with pressure, corresponding to 0.5 ⊥ 0.2°C/kbar between 960 and 1100°C.