Antimonys exchange with

In cases where only difluorophosphanes are formed from dichlorophosphanes by halogen exchange with antimony(III) fluoride, the former can be converted into tetrafluoro-25-phosphanes by treatment with chlorine gas in the presence of antimony(III) fluoride.46,52... 

Table 2. Synthesis of Fluorohaloalkanes through Halogen Exchange with Antimony Halides/Hydrogen Fluoride...

In oxidizing soil solutions, Sb is likely to form the anionic molecule Sb(OH)6, above pH 4, and SbCOH) in more acid solution. As an anion, Sb(OH)6 may adsorb by ligand exchange on oxides and silicate clays. Antimony associates with ferric hydroxide in soils, perhaps a result of chemisorption of the anion on this mineral. 

Table I. Synthesis of Fluorohuloalkanes through Halogen Exchange with Antimony fluorides...

O vs. N Protonation.—Controversy over the site of protonation of amides has been raised anew by Liler. Using u.v. spectroscopy, she has suggested that benzamide is 50 50 O N protonated in 80 % sulphuric acid. However, a considerable weight of evidence has been produced to indicate that protonation or Lewis acid complexation of amides consistently occurs by co-ordination with oxygen. Studies have included the acidity-dependent changes in the tt-tt and n-it u.v. absorption bands of aliphatic amides kinetic evidence based on rate data for acid-catalysed amide hydrolysis in both dilute and concentrated acid an n.m.r. study of proton exchange rates, where for A -methylacetamide the molar ratio of 0 N protonated species exceeds 10 a n.m.r. study of adducts of boron trifluoride and antimony pentachloride with N-labelled ureas, where the hybridization-dependent —H coupling constants were inconsistent with N-co-ordination ... 

When used with antimony pentachloiide, the reactivity of HF is comparable to SbCl2F2 alone. Therefore a continuous fluorination exchange process is possible where antimony is the fluoride carrier from FIF to the organic fluoride. 

The standard synthesis method features side-chain chlorination of a methylpyridine (picoline), followed by exchange-fluoriaation with hydrogen fluoride or antimony fluorides (432,433). The fluoriaation of pyridinecarboxyHc acids by sulfur tetrafluoride (434) or molybdenum hexafluoride (435) is of limited value for high volume production operations due to high cost of fluorinating agent. 

A.sahi Chemical EHD Processes. In the late 1960s, Asahi Chemical Industries in Japan developed an alternative electrolyte system for the electroreductive coupling of acrylonitrile. The catholyte in the Asahi divided cell process consisted of an emulsion of acrylonitrile and electrolysis products in a 10% aqueous solution of tetraethyl ammonium sulfate. The concentration of acrylonitrile in the aqueous phase for the original Monsanto process was 15—20 wt %, but the Asahi process uses only about 2 wt %. Asahi claims simpler separation and purification of the adiponitrile from the catholyte. A cation-exchange membrane is employed with dilute sulfuric acid in the anode compartment. The cathode is lead containing 6% antimony, and the anode is the same alloy but also contains 0.7% silver (45). The current efficiency is of 88—89%, with an adiponitrile selectivity of 91%. This process, started by Asahi in 1971, at Nobeoka City, Japan, is also operated by the RhcJ)ne Poulenc subsidiary, Rhodia, in Bra2il under Hcense from Asahi. 

Admiralty brass (70% Cu, 29% Zn, 1% Sn, 0.05% As or Sb) and arsenical aliuninum brass (76% Cu, 22% Zn, 2% Al, 0.05% As) are resistant to dezincification in most cooling water environments. In the recent past, heat exchangers have virtually always been tubed with inhibited grades of brass. Brasses containing 15% or less zinc are almost immune to dezincification. Dezincification is common in uninhibited brasses containing more than 20% zinc. Inhibiting elements include arsenic, antimony, and phosphorus. Without inhibiting elements. 

In the case of ester exchange for the manufacture of poly(ethylene terephthalate), a low molecular weight diester, known as the monomer , is first prepared by reacting 1 mol of dimethyl terephthalate with about 2.1-2.2 mol ethylene glycol at about 150°C in the presence of catalysts such as antimony trioxide and cobaltous acetate ... 

The catalysts at the anode can be made less sensitive to CO poisoning by alloying platinum with other metals such as ruthenium, antimony or tin[N.M. Markovic and P.N. Ross, New Flectro catalysts for fuel cells CATTECH 4 (2001) 110]. There is a clear demand for better and cheaper catalysts. Another way to circumvent the CO problem is to use proton-exchange membranes that operate at higher temperatures, where CO desorbs. Such membranes have been developed, but are not at present commercially available. 

After adjusting to 2 mol 1 1 in hydrochloric acid, 500 ml of the sample is adsorbed on a column of Dowex 1-XS resin (Cl form) and elution is then effected with 2 M nitric acid. The solution is evaporated to dryness after adding 1M hydrochloric acid, and the tin is again adsorbed on the same column. Tin is eluted with 2 M nitric acid, and determined in the eluate by the spectrophotometric catechol violet method. There is no interference from 0.1 mg of aluminium, manganese, nickel, copper, zinc, arsenic, cadmium, bismuth, or uranium any titanium, zirconium, or antimony are removed by ion exchange. Filtration of the sample through a Millipore filter does not affect the results, which are in agreement with those obtained by neutron activation analysis. 

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