L antimony

Fermor, L. L, Antimony in Shan States, Sec. Geol. Sum. India,... 

Calibration Curve - The counts per second are plot versus pg/L antimony in the standard series. 

Shanthi E, Dutta V, Baneqee A and Chopra K L 1980 Electrical and optical properties of undoped and antimony-doped tin oxide films J. Appi. Rhys. 51 6243-51... 

Fig. 1. Paiticle size distribution of the antimony oxides A, Thermoguard UF B, Thermoguard S C, Thermoguard L.

The mechanism by which tin flame retardants function has not been well defined, but evidence indicates tin functions in both the condensed and vapor phases. In formulations in which there is at least a 4-to-l mole ratio of halogen to tin, reactions similar to those of antimony and halogen are assumed to occur. Volatile stannic tetrahaUde may form and enter the flame to function much in the same manner as does antimony trihaUde. 

The standard electrode potential for zinc reduction (—0.763 V) is much more cathodic than the potential for hydrogen evolution, and the two reactions proceed simultaneously, thereby reducing the electrochemical yield of zinc. Current efficiencies slightly above 90% are achieved in modem plants by careful purification of the electrolyte to bring the concentration of the most harmful impurities, eg, germanium, arsenic, and antimony, down to ca 0.01 mg/L. Addition of organic surfactants (qv) like glue, improves the quaUty of the deposit and the current efficiency. 

Lewis Acid Complexes. Sulfolane complexes with Lewis acids, such as boron trifluoride or phosphoms pentafluoride (17). For example, at room temperature, sulfolane and boron trifluoride combine in a 1 1 mole ratio with the evolution of heat to give a white, hygroscopic soHd which melts at 37°C. The reaction of sulfolane with methyl fluoride and antimony pentafluoride inhquid sulfur dioxide gives crystalline tetrahydro-l-methoxythiophenium-l-oxidehexafluoroantimonate, the first example of an alkoxysulfoxonium salt (18). 

Cyclic and Polymeric Substances Containing Antimony-Antimony Bonds. A number of oiganoantimony compounds containing rings of four, five, or six antimony atoms have been prepared. The first such compound to be adequately characterized, tetrakis-l,2,3,4-/f i-butyltetrastibetane [47191 -73-5], Cj H Sb, was obtained by the interaction of a dialkylstibide and iodine (70) ... 

Antimonin and its Derivatives. Antimonin(stibaben2ene) [289-75-8] CgH Sb, the antimony analogue of pyridine, can be prepared by the dehydrohalogenation of a cycHc chlorostibine using l,5-dia2abicyclo[4.3.0]non-5-ene (141) ... 

G. O. Doak and L. D. Freedman, Organometallic Compounds of Arsenic, Antimony, and Bismuth,]ohn Wiley Sons, Inc., New York, 1970. 

Addition Chlorination. Chlorination of olefins such as ethylene, by the addition of chlorine, is a commercially important process and can be carried out either as a catalytic vapor- or Hquid-phase process (16). The reaction is influenced by light, the walls of the reactor vessel, and inhibitors such as oxygen, and proceeds by a radical-chain mechanism. Ionic addition mechanisms can be maximized and accelerated by the use of a Lewis acid such as ferric chloride, aluminum chloride, antimony pentachloride, or cupric chloride. A typical commercial process for the preparation of 1,2-dichloroethane is the chlorination of ethylene at 40—50°C in the presence of ferric chloride (17). The introduction of 5% air to the chlorine feed prevents unwanted substitution chlorination of the 1,2-dichloroethane to generate by-product l,l,2-trichloroethane. The addition of chlorine to tetrachloroethylene using photochemical conditions has been investigated (18). This chlorination, which is strongly inhibited by oxygen, probably proceeds by a radical-chain mechanism as shown in equations 9—13. 

In the presence of catalysts, trichloroethylene is readily chlorinated to pentachloro- and hexachloroethane. Bromination yields l,2-dibromo-l,l,2-trichloroethane [13749-38-7]. The analogous iodine derivative has not been reported. Fluorination with hydrogen fluoride in the presence of antimony trifluoride produces 2-chloro-l,l,l-trifluoroethane [75-88-7] (8). Elemental fluorine gives a mixture of chlorofluoro derivatives of ethane, ethylene, and butane. 

Dichlorotoluene (2,4-dichloro-l-methylben2ene) constitutes 80—85% of the dichlorotoluene fraction obtained in the chlorination of PCT with antimony trichloride (76) or zirconium tetrachloride (77) catalysts. It is separated from 3,4-dichlorotoluene (l,2-dichloro-4-methylben2ene), the principal contaminant, by distillation. Chlorination of OCT with sulfuryl chloride gives mainly 2,4-dichlorotoluene and small amounts of the 2,3 isomer (78). 

Although some changes occur in the melting furnace, cathode impurities are usually reflected directly in the final quaUty of electrorefined copper. It is commonly accepted that armealabiUty of copper is unfavorably affected by teUurium, selenium, bismuth, antimony, and arsenic, in decreasing order of adverse effect. Silver in cathodes represents a nonrecoverable loss of silver to the refiner. If the copper content of electrolyte is maintained at the normal level of 40—50 g/L, and the appropriate ratio of arsenic to antimony and bismuth (29) is present, these elements do not codeposit on the cathode. 

The final ceU product contains 250—300 g/L H2SO in the last stages of electrolyte purification, and antimony and bismuth precipitate, resulting in heavily contaminated cathodes that are recycled through the smelter. Arsenic and hydrogen evolved at the cathodes at these later stages react to form arsine, and hoods must be provided to collect the toxic gas. 

The stabilized fluorinated allylic cation, generated from cis- or trans-l-(p-methoxyphenyl)pentafluoropropene and antimony pentafluoride in sulfur dioxide, is solvolyzed by methanol to methyl 2-(p-methoxyphenyl)difluoroacrylate [36] (equation 37)... 

A one-pot synthesis of alkyl perfluoroalkyl ketones has been developed. Phosphoranes, generated in situ, are acylated with a perfluoroacyl anhydnde, and the resultmg phosphonium salts are hydrolyzed with alkali [4S (equation 48) Hydrolysis of a carbon-sulfur bond in 2-chloro-2,4,4-trifluoro-1,3-dithietane-S-trioxide, which can be obtained from 2,2,4,4-tetrachloro-l,3-dithietane by fluor-mation with antimony trifluoride followed by selective oxidations, opens the nng to produce 2-chloro-1,1,2-trifluorodimethyl sulfone [49] (equation 49)... 

The reactions of some fluorinated ethers may result in the elimination of alkyl fluorides In the case of 2-methoxyperfluoro-2-butene, treatment with antimony pentafluoride gives perfluoro-3-buten-2-one and methylfluoride [107] By reacting 2-chloro-l,l,2-trifluorodiethyl ether with boron trifluoride etherate or with aluminum chloride, chlorofluoroacetyl fluoride can be obtained with the elimination of ethyl fluonde [108] (equations 76 and 77)... 

Isomerization of fluoroolefins by a shift of a double bond is catalyzed by halide 10ns [7] The presence of crown ether makes this reaction more efficient [74] Prolonged reaction time favors the rearranged product with an internal double bond (equations 3-5) Isomerization of perfluoro-l-pentene with cesium fluoride yields perfluoro-2-pentenes in a Z ratio of 1 6 [75] Antimony pentafluoride also causes isomenzation of olefins leading to more substituted products [76]... 

Covalent fluondes of group 3 and group 5 elements (boron, tin, phosphorus, antimony, etc ) are widely used m organic synthesis as strong Lewis acids Boron trifluoride etherate is one of the most common reagents used to catalyze many organic reactions. A representative example is its recent application as a catalyst in the cycloadditions of 2-aza-l,3-dienes with different dienophiles [14] Boron trifluoride etherate and other fluonnated Lewis acids are effective activators of the... 

Although antimony pentafluonde can fluorinate l,l,2-tnchloro-l,2,2-trifluo-roethane to chloropentafluoroethane, this route is not used industnally because antimony pentafluonde and hydrogen fluoride are too corrosive. Both dichloro-tetrafluoroethane and chloropentafluoroethane are produced by vapor-phase fluor-ination of tetrachloroethene with proprietary chromia catalysts at 300 to 500 °C (equation 1). 

AlLiiiiiiilLim Antimony Argon. . Arsenic barium Berylliu m Bismuth boron. . bromine. Cadmium Caesium, Calcium Carbon ( erium ( hloriiie. Cliromium L obait. . Copper. . Muorine. ... 

Formulations of this type have completely replaced earlier "strike anywhere matches based on (poi.sonous) white P4, sulfur, and KCIO3. though safety matches" still use a match head which is predominantly KCIO3 struck against the side of the match-box which has been covered with a paste of (non-toxic) red P (49.5%), antimony sulfide (27.6%). FeiOr (l.2%) and gum arabic (2I,7%). About lO" matches are used annually in the UK alone. 

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