Oxidation with Halogens

6-Tri-tert-butyl-X -phosphorin24 readily reacts with bromine and with chlorine. Mach oxidizing with bromine in CCI4, could not isolate a crystalline product. The brown colour of the addition product of one mole Br2 to one mole 24 disappeared with water and the crystalline 2-hydro-phosphinic acid 85b could be isolated in 45% yield. Methyl-magnesium-iodide or red phosphorus yielded 2.4.6 tri-tert-butyl-X -phosphorin 24. It seems reasonable to suppose that on bromination l.l-dibromo-2.4.6-tri-tert-butyl-X -phosphorin was formed. 

In CCI4,2.4.6-tri-tert-butyl-phosphorin24 absorbed 2 moles of chlorine. 

Mach isolated a crystalline stericaUy uniform substance, m.p. 77-78,5 °C, identified as 4-chloro-phosphinic acid chloride 94. 1.1.1.4-Tetra-chloro-2.4.6-tri-tert-butyl-X -phosphorin 93 is assumed to be the primary chlorination product. 

94 with sodium methanolate ves the two isomers 84 on alcoholysis and hydrolysis. With sodium ethanolate under carefully controlled conditions the 4-chloroethyl ester 95, m.p. 155 °C, could be isolated as a stericaUy uniform com- 

Recent experiments of Kanter with 2.4.6-triphenyl-X -phosphorine 22 seem very promising. With bromine and light or with pyri ne perbromide in the dark, 

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Oxidation with halogens gives the decahalogenodiosmate (IV) (2-) ions (Figure 1.6) ... 

Oxidation with halogens and compounds containing electropositive ... 

With very few exceptions, quantitative epoxide assay techniques currently in use are derived from the reeotion of ethylene oxides with halogen adds, notably hydrochloric acid and hydrobromio add, in a variety of solvents. Acid uptake may be determined by any of several reliable procedures. These include titration with standard base8 nr back-titration with standard acid.744 The end-point may be detected visually in the presence of suitable acid-base indicators, or by the more precise technique of potontionaetry.447.4 -470 A useful alternative, applicable in the presence of easily hydrolysed substances or of amines that buffer the end-point, is the technique of argentiometry. In this procedure excess of halide ion is titrated with silver nitrate in tV presence of ferric thiocyanate indicator,470 1884 or potentiometri-cally.188 ... 

The oxidation with halogens and hypohalites is a complicated reaction, as it depends strongly on the conditions of temperature, acidity, and concentration of the reacting species. The halogens show considerable differences in the positions of the various equilibria and the speed with which the equilibria are attained (see Table I). In acidic solution, the equilibrium between free halogen and hypohalous acid [Eq. (7. )] lies far to the left, and the concentration of hypohalous acid is very low. When alkali is added to the system, the concentration of hypohalite ion increases, according to Eq. (14). 

Maximal rates of oxidation of sugars by chlorine and bromine have been observed near neutrality and several studies have been conducted in order to establish the identity of the active oxidant as well as the mechanism of the reaction (Ref. 1, pp. 1116, 1117). As for other related oxidations with halogens, ft anomers of glycosides react more rapidly than the a anomer... 

The oxidizing power of halogens decrease with increasing relative atomic mass Iodine is a mild oxidant, while the iodide ion often acts as reducing agent. Some oxidations with halogens, used in qualitative analysis, are as follows ... 

A -Dioxaphospholanes show no inversion at the phosphorus atom, which can be seen in the nonequivalence of the CFj groups (273). A -Dioxaphospholanes 73 can be oxidized with halogens to form A -dioxaphospholanes 74 (228). Exchange of the halogens in 73a-c with suitable reaction partners (e.g., LiNHj) yields substituted A -phospholanes [e.g., 73g (265)] (see also Section III,A,2). 

On oxidation with halogens, the [Au(CN)2] ion forms irani-[Au(CN)2X2] (X = Cl, Br, 1). The cyanide complex anion, [Au(CN)4] , is prepared by the exchange reaction between [AuCU]" and CN" ions. The square-planar [Au(CN)4] anion further reacts with cyanide ions in aqueous solution to form [Au(CN)5] and [An(CN)6] ions. 

The Iu4 cluster can be completely or partial oxidized with halogen or chalcogen to form 104X4 heterocubanes or mixed-valence compounds. The complex In4[C(SiMe3)3]4 abstracts O from o-nitrosotoluene forming the extremely... 

Oxohalides are common Re02p3, ReOFs, ReOsX, ReOX4, and ReOXs (X = F, Cl, Br), as well as TCO3X, TcOXi (X = Cl, F), and TcOCls, are known. The oxohalides can be prepared by treatment of the hahdes with oxygen or of the oxides with halogens. Both the halides and the oxohalides with the oxidation states -1-5 and -1-6 readily hydrolyze with disproportionation to [M04] andM02. 

III. Oxidation with Halogen Acids in Acid Solution. 178... 

An ob% ious method of obtaining these halides is to treat the corresponding oxides with halogen acids ... 

Opening of the vicinal carbon-carbon bond in aminocyclopropane derivatives was achieved by oxidation with various reagents, e.g. Pb(OAc)4 , NaOCP r-BuOCpi Cu2 /0 Cu/0 0s04/0 K3Fe(CN) Cu or fiv/Oa/sens., anodic oxidation Oxidation with halogenating reagents such as NaOCl or t-BuOCl proceeds via N-chloro compounds (see equation 105), which opened the C(l)-C(2) cyclopropane bond when the cyclopropylamine had one substituent at the iV-atom (e.g. 489- 490 equation 125) or a phenyl moiety in the C(2) position. 

They are prepared by reacting oxides with halogens, or halides with O2, or by reactions such as 22.64 and 22.65. Whereas ReOp5 can be prepared by the high-temperature reaction between ReOy and Fy, the Tc analogue must be made by reaction 22.66 because the reaction of Fy and TcOy gives TcOyF. 

Analysis of mixtures of lower oxo acids of phosphorus and their salts is a relatively difficult problem, especially when a number of the oxo acids or their salts are presen t in a given sample. The chemical approach to this problem is based on the fact that, under certain conditions, one acid will be readily oxidized or hydrolyzed and another will not. Preferential oxidation with halogens, particularly iodine, has been the basis of a number of procedures for differential analysis. 

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