Chloroplatinic

HjSnCl, with which the aniline forms a salt, aniline chlorostannate (C4HjNH )i,H SnCl4, similar in type to aniline chloroplatinate (p. 448). The crude product is therefore made strongly alkaline with sodium hydroxide, which liberates the base with the formation of sodium stannate, and the aniline can (C4H NH,),H,SnCl, + SNaOH = 2C,H,NH, + Na.SnO, +6NaCl + sHjO then be removed by steam-distillation. 

IL Molecular Weight of Acids by Titration with Standard Alkali. III. Molecular Weight of Bases by Analysis of Chloroplatinates. 

When platinum is dissolved in aqua regia it is first converted to platinic chloride, PtCl, and the latter at once unites with the excess of hydrochloric acid to give the stable soluble dibasic chloroplatinic acid, HjPtCle.f... 

When an amine, or a solution of its hydrochloride, is added to an aqueous solution of chloroplatinic acid, a salt of the base with the cliloroplatinic acid, of general formula BjiHiPtCle (where B is one molecule of the base) is formed and usually crystallises out, for these chloroplatinates hai e normally a rather low solubility in cold water. The chloroplatinate can be filtered off, dried, and then analysed by direct ignition, when only the metallic platinum ultimately remains. Knowing the percentage of platinum in the chloroplatinate, the molecular weight of the latter, and hence of the constituent base, can readily be calculated. 

Then, since Atomic Weight of platinum = 195 2, if g g. platinum is obtained from G g. chloroplatinate,... 

Alternatively, the bulk of the platinum in the aqueous residues can be precipitated by ammonium chloride as ammonium chloroplatinate, the latter filtered off, and the filtrate evaporated to dryness. The chloroplatinate and the residue from the evaporation are then ignited. 

The chloroplatinates prepared as above are sufficiently pure for direct analysis without recrystallisation. The chloroplatinates of the amines are usually freely soluble in hot water, but recrystallisation (when required) should not be attempted until the process has been found to be successful with a small test-portion of the chloroplatinate. The chloroplatinates of many primary and secondary amines decompose in hot water, the amine being oxidised, and the chloroplatinate reduced to the metal some amines furthermore co-ordinate readily with the metal when the chloroplatinate is boiled with water and a mixed product is obtained on cooling. 

Many chloroplatinates separate from aqueous solution with water of crystallisation. If this is suspected, the chloroplatinate should be dried to constant weight in the oven before analysis, to ensure elimination of water of crystallisation. Aniline, p-toluidine and pyridine all give anhydrous chloroplatinates, and can be conveniently used in the above determination no attempt should be made to recryrtallise their chloroplatinates. 

Method 1. From ammonium chloroplatinate. Place 3 0 g. of ammonium chloroplatinate and 30 g. of A.R. sodium nitrate (1) in Pyrex beaker or porcelain casserole and heat gently at first until the rapid evolution of gas slackens, and then more strongly until a temperature of about 300° is reached. This operation occupies about 15 minutes, and there is no spattering. Maintain the fluid mass at 500-530° for 30 minutes, and allow the mixture to cool. Treat the sohd mass with 50 ml. of water. The brown precipitate of platinum oxide (PtOj.HjO) settles to the bottom. Wash it once or twice by decantation, filter througha hardened filter paper on a Gooch crucible, and wash on the filter until practically free from nitrates. Stop the washing process immediately the precipitate tends to become colloidal (2) traces of sodium nitrate do not affect the efficiency of the catalyst. Dry the oxide in a desiccator, and weigh out portions of the dried material as required. 

Method 2. From chloroplatinic acid. Dissolve 3 - 5 g. of the purest commercial chloroplatinic acid (3) in 10 ml. of water contained in a 250 ml. P3rrex beaker or porcelain casserole, and add 35 g. of A.R. sodium nitrate (1), Evaporate the mixture to dryness by heating gently over a Bunsen flame whilst stirring with a glass rod. Then raise the temperature... 

It is insoluble in hydrochloric and nitric acid, but dissolves when they are mixed as aqua regia, forming chloroplatinic acid. 

Chloroplatinic acid, H2PtClg 6H2O—10% solution dissolve 1 g in 9 mL of water keep in a dropping bottle. 

At 165°C and in the presence of chloroplatinic acid as catalyst, isoprene reacts with trichlorosilane, metbyldicblorosilane, ethyldichlorosilane, ben2yldichlorosilane, and diben2ylchlorosilane (72). The addition is 1,4- with the substituted silane group attaching to the first carbon atom. 

Catalysis. Platinum-catalyzed hydrosilation is used for cross-linking siUcone polymers and for the preparation of functionally substituted silane monomers (250). The most widely used catalyst is chloroplatinic acid (Spier s catalyst), H2PtCl3. Other compounds that catalyze the reaction include Pt(Il)... 

Miscellaneous. Chloroplatinic acid is used in the production of automobile catalysts. Platino-type prints based on reduction of Pt(II) to Pt(0) by a photosensitive reducing agent such as iron(III) oxalate are used in art photography (261,262). Infrared imaging devices based on a platinum siLicide detector have been developed (263). 

Color. Many water samples have a yellow to brownish-yeUow color which is caused by natural substances, eg, leaves, bark, humus, and peat material. Turbidity in a sample can make the measurement of color uncertain and is usually removed by centrifiigation prior to analysis. The color is usually measured by comparison of the sample with known concentrations of colored solutions. A platinum—cobalt solution is used as the standard, and the unit of color is that produced by 1 mg/L platinum as chloroplatinate ion. The standard is prepared from potassium chloroplatinate (K PtCl ) and cobalt chloride (C0CI26H2O). The sample may also be compared to suitably caUbrated special glass color disks. 

Pla.tinum, Platinum plating has found appHcation in the production of platinised titanium, niobium, or tantalum anodes which are used as insoluble anodes in many other plating solutions (see Metalanodes). Plating solutions were often based on platinum "P" salt, which is diamminedinitroplatiniim (IT). A dinitroplatinite sulfate—sulfuric acid bath has been used to plate direcdy onto titanium (129). This bath contains 5 g/L of the platinum salt, pH adjusted to 2.0 with sulfuric acid. The bath is operated at 40°C at 10—100 A/m. Other baths based on chloroplatinic acid have been used in both acid and alkaline formulations the acid bath uses 20 g/L of the platinum salt and 300 g/L hydrochloric acid at 65° C and 10—200 A/m. The alkaline bath uses 10 g/L of the platinum salt, 60 g/L of ammonium phosphate and ammonium hydroxide to give a pH of 2.5—9.0. The alkaline bath can be plated directly onto nickel-base alloys acid baths require a gold strike on most metals. 

There are two ways to produce acetaldehyde from ethanol oxidation and dehydrogenation. Oxidation of ethanol to acetaldehyde is carried out ia the vapor phase over a silver or copper catalyst (305). Conversion is slightly over 80% per pass at reaction temperatures of 450—500°C with air as an oxidant. Chloroplatinic acid selectively cataly2es the Uquid-phase oxidation of ethanol to acetaldehyde giving yields exceeding 95%. The reaction takes place ia the absence of free oxygen at 80°C and at atmospheric pressure (306). The kinetics of the vapor and Uquid-phase oxidation of ethanol have been described ia the Uterature (307,308). 

UV spectra, 3, 955 X-ray crystallography, 3, 948 Thianthrenium salts, 5-phenyl-chloroplatinate salts, 3, 967 Thianylium salts chlorination, 3, 901 1,2A -Thiaphosphiranes synthesis, 7, 196 Thiapyrans — see Thiins l,3A -Thiarsoles nomenclature, 1, 32 Thiaselenafulvenes synthesis, 6, 965 Thiaselenins synthesis, 3, 914... 

When a carrier is impregnated with a solution, where the catalyst deposits will depend on the rate of diffusion and the rate of adsorption on the carrier. Many studies have been made of Pt deposition from chloroplatinic acid (HgPtClg) with a variety of acids and salts as coim-pregnants. HCl results in uniform deposition of Pt. Citric or oxalic acid drive the Pt to the interior. HF coimpregnant produces an egg white profile. Photographs show such varied distributions in a single pellet. 

Acetylcholine chloride [60-31-1] M 181.7, m 148-150 , 151". It is very sol in H2O (> 10%), and is very hygroscopic. If pasty, dry in a vacuum desiccator over H2SO4 undl a solid residue is obtained. Dissolve in abs EtOH, filter and add dry Et20 and the hydrochloride separates. Collect by filtration and store under very dry conditions. [J Am Chem Soc 52 310 1930.] The chloroplatinate crystallises from hot H2O in yellow needles and can be recrystd from 50% EtOH, m 242-244° [Biochem J 23 1069 7929], other m given is 256-257°. The perchlorate crystallises from EtOH as prisms m 116-117°. [J Am Pharm Assocn 36 272 1947.]... 

Ammonium chloroplatinate often can be used to advantage in place of chloroplatim c acid in the preparation of Adams catalyst. A mixture of 3 g. of ammonium chloroplatinate and 30 g. of sodium nitrate in a casserole or Pyrex beaker is heated gently at first until the rapid evolution of gas slackens and then more strongly until a temperature of 500° is reached. This operation requires about fifteen minutes and there is no spattering. The temperature is held at 500-520° for one-half hour and the mixture is then allowed to cool. The platinum oxide catalyst, collected in the usual way by extracting the soluble salts with water, weighs 1.5 g. and it is comparable in appearance and in activity to the material prepared from chloroplatinic acid. 

This procedure is particularly time-saving when scrap platinum or spent catalyst is used for the preparation of platinum oxide, for after conversion to chloroplatinic acid a purification is conveniently effected by precipitating the ammonium salt, and the direct fusion of this with sodium nitrate eliminates the tedious process of reconversion to chloroplatinic acid. Furthermore ammonium chloroplatinate is not hygroscopic and can he accurately weighed. The amount of catalyst obtained is almost exactly half the weight of the ammonium salt employed. 

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