Palladium history

Hardness of the aimealed metals covers a wide range. Rhodium (up to 40%), iridium (up to 30%), and mthenium (up to 10%) are often used to harden platinum and palladium whose intrinsic hardness and tensile strength are too low for many intended appHcations. Many of the properties of rhodium and indium. Group 9 metals, are intermediate between those of Group 8 and Group 10. The mechanical and many other properties of the PGMs depend on the physical form, history, and purity of a particular metal sample. For example, electrodeposited platinum is much harder than wrought metal. 

Palladium, polymethylenebis(diphenylphosphine)-bis(thiocyanato)-linkage isomers, 1, 185 Palladium, tetraammine-tetrachloropalladate history, 1, 2 Palladium, tetrachloro-crystal structure, 1, 16 Palladium, tris(dinitrogen)-synthesis, 1,28 Palladium complexes a,(5-dione dioximates electrical properties, 6, 143 acetylacetone hydrolysis, 2,379 alkylperoxo... 

The earliest scientific descriptions of platinum, are those of Dr. Brownrigg and Don Antonio de UUoa in the middle of the eighteenth century. Rhodium, palladium, osmium, and iridium were discovered in 1803 and 1804, the first two by Dr. Wollaston and the others by his friend, Smithson Tennant. Thomsons History of Chemistry and Berzelius correspondence and diary present a pleasing picture of these two great English chemists. Ruthenium, the Russian member of the platinum family, was discovered much later by Karl Karlovich Klaus, whose life story was beautifully told by Professor B. N Menschutkin of the Polytechnic Institute of Leningrad. 

Tennant gave the name iridium to the metal which Descotils and Vauquelin had observed, and the name osmium to the new one (20). In speaking of iridium, osmium, palladium, and rhodium, W. T. Braude stated in his lectures in 1817, Of these, the two former were discovered by the late Mr. Tennant and the two latter by Dr. Wollaston and bad we searched throughout chemistry for an illustrative instance of the delicacy of the modem art of analysis, it would be difficult to have found any one more notorious than the history of the discovery and separation of these bodies exhibits (46). During the entire course of the researches which led to ibe discovery of these four metals, Dr. Wollaston and Tennant had friendly intercourse with each other, and each kept in close touch with... 

Occurrence and History.—Palladium occurs native along with platinum in Brazil,1 St. Domingo, and the Urals. It is also found alloyed with gold as the mineral porpesite, the name being derived from Porpez in Brazil. Of tliis alloy the following may be taken as a typical analysis 2 ... 

Occurrence and History of Palladium—Preparation—Physical Varieties Physioal Properties—Permeability to Hydrogen--Occlusion of Canos Occlusion of Hydrogen—Chemical Properties--Catalytic Activity Crystalline Palladium—Colloidal Palladium—Spongy Palladium —Palladium Black —Uses—Atomic Weight—Alloys. 

It will be observed that all of the meteorites contain, in addition to nickel, a small quantity of cobalt, whilst the carbon content is extremely small. Carbon is sometimes present in meteoric iron in the form of minute diamonds.2 The Rowton specimen is interesting as being the first sidente observed to fall in Great Britain, and may be seen in the Natural History Museum, South Kensington. The Perryville siderite is the first recorded instance of the presence of ruthenium in meteoric iron. In addition to traces of this element, traces of iridium, palladium, and platinum were detected. 

The history of hydrogen activation using a heterogenous catalyst (solid) dates back as early as 1823 when Dobereiner noted that hydrogen inflames spontaneously upon contact with finely divided platinum. Some 50 yr later chemists began to experiment with nickel, copper, iron, palladium, and other metals for... 

The first edition of Palladium in Heterocyclic Chemistry - A guide to the Synthetic Chemist, published five years ago, was warmly received by many readers. Five years is a fleeting interval in scientific history, but palladium chemistry in general, and palladium in heterocyclic chemistry in particular, has matured considerably. In order to make the second edition more thorough and up-to-date, we aie fortunate to have recruited a group of stellar authors to take on the challenge. As a consequence, not only have we attempted to improve and update each chapter, but we have also added three new chapters Chapter 12 Quinolines Chapter 13 Pyridazines Chapter 14 Industrial scale palladium chemistry. We are indebted to all authors for their contributions. 

Historically, it took many years to achieve the almost perfect stereocontrol of an enantioselechve hydrogenahon reaction using a heterogeneous catalyst, with a resultant 97-99% enanhomeric excess (ee) of the product One of the oldest such examples is that of tartaric acid-modified platinum black for the hydrogenahon of an oxime to give a chiral amine of <20% ee [2]. Nonetheless, many reviews in this field have provided a clear history of the enanhoselechve catalysis from silk-palladium-a palladium metal supported on a chiral silk fiber to hydrogenate a... 

The crystal structures of Zeise s salt and of two analogous palladium-olefin complexes were published,shortly after the publication of the Chatt-Duncanson paper. They confirmed the structural proposals made by Chatt, but none of these papers cites Dewar,though metal-olefin bonding models were not discussed. Two short reviews on the history of Zeise s salt, (one part of a more general discussion of the history of organometallic chemistry) also only refer to Chatt s contribution, though neither specifically address questions of bonding. 

Palladium-based catalysts are the most active materials for the total oxidation of methane in the presence of excess oxygen. The structure and chemical identity of the species present on the surface of these materials have a decisive influence on their specific activity and time-dependent behavior. Since the structure and composition of these species strongly depend on preparation, pretreatment, thermal history, and reaction conditions, a very broad range of specific activities... 

Palladium, polymethylenebis(diphenylphosphine)-bis(thiocyanato)-linkage isomers, 185 Palladium, tetraammine-tetrachloropalladate history, 2... 

The history of direct DPC process development at GE can be considered as a case study. In the mid-1970s. Chalk discovered that /rara-substituted phenols can be oxidatively carbonylated using stoichiometric amounts of a Ru, Rh, Os, Ir, or Pd salt, from which the palladium salts were the most active (Eq. (12.3)) [5]. Yields of carbonylation products were high, but the reaction yielded 1 mol of Pd° for every mole of product, so it was stoichiometric [6]. In the late 1970s, Hallgren and Matthews assumed that DPC was formed by reductive elimination from the acyl Pd(ll) carbonyl complex [7]. 

For example, effective intermediate layers have been developed that create a smoother support surface to minimize defect density and reduce metallic interdiffusion. The following sections of this chapter examine the history, background, and applications of palladium membranes, including recent advances in fabrication methods and performance. 

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