Phosphorus unreactive

The development of a brown color indicates that sufl cient phosphorus oxytrichloride has been added. If the mixture remains colorless, the final product is likely to be contaminated with unreacted iV-( -tolylsulfonylmethyl)formamide. It is therefore advantageous to add more phosphorus oxjrtrichloride and continue stirring until the brown color is obtained. 

Whereas l,2-0-isopropylidene-5,6-di-0-methyl-D-glucofuranose was found to be unreactive towards triphenylphosphite dibromide, triphenylphosphite methiodide or phosphorus pentachloride, the related methyl 2,5,6-tri-0-methyl-/ -D-glucofuranoside (59), in which the hindrance caused by the ketal group is absent, reacted with triphenylphosphite methiodide to give the 3-deoxy-3-iodo derivative 60 in 31% yield. 

Nanny, M. A. and Minear, R. A. (1997). Characterization of soluble unreactive phosphorus using P nuclear magnetic resonance spectroscopy. Mar. 

A. Preparation of a-bromoisobutyryl bromide. To a mixture of 250 g. (2.85 moles) of isobutyric acid and 35 g. (1.13 moles) of red phosphorus in a 1-1. three-necked flask, fitted by ground-glass joints to a dropping funnel, mechanical stirrer, and reflux condenser, is added, dropwise with stirring, 880 g. (5.5 moles) of bromine. After the addition is complete, the solution is warmed to 100° over a period of 6 hours. The unreacted bromine and hydrogen bromide are removed under reduced pressure (30 mm.). The a-bromoisobutyryl bromide is decanted from the phosphorous acid and fractionated through a short helices-packed column. After a considerable fore-cut, the main fraction, 493-540 g. (75-83%), is collected at 91-98° (100 mm.). 

Figure 5.15. Gas chromatograms of liquid precursors for producing n-type Si films, namely, solution of CPS with white phosphorus dissolved at 1 wt% initial (nonirradiated) solution 20-min-, 25-min-, and 30-min-irradiated solutions and white phosphorus alone solution, for comparison, all of which were diluted with toluene before analysis. Trans-decalin was used as a standard for a quantitative estimation of an unreacted CPS monomer. [Reproduced with permission from Ref. 25. Copyright 2007 The Japan Society of Applied Physics.]...

Red phosphorus in an aqueous basic medium has also been used in the preparation of a-hydroxyphosphonites (Figure 2.7).23 Aromatic and a,p-unsaturated aldehydes added to the reaction mixture undergo nucleophilic attack by the intermediate phosphine species in a manner reminiscent of the approach of Pudovik and Arbuzov24 using partially esterified phosphites and aldehydes. Reaction of the red phosphorus suspension is noted to be enhanced by the use of ultrasonication an excess of elemental phosphorus is used, and excess unreacted red phosphorus must be removed by filtration in the product isolation process. 

A solution of 10 ml of 10 N aqueous KOH diluted to 25 ml with absolute ethanol was added dropwise over a period of 30 min to a well-stirred mixture of 0.4 g-atom (12.4 g) of finely divided white phosphorus, 1.2 mol (85.2 g) of acrylamide, and 200 ml of absolute ethanol under a nitrogen atmosphere. The temperature was maintained at -5 to 0°C by a cooling bath. After stirring for an additional 45 min, the white solid generated was recovered by filtration. This solid was dissolved in 125 ml of hot glacial acetic acid, and the solution was cooled to room temperature. (Any unreacted white phosphorus could be removed at this point by decantation under a nitrogen atmosphere.) The solution was filtered through diatoma-ceous earth, diluted with 600 ml of absolute ethanol, and cooled at 5°C for 30 min. The resultant white solid was collected by filtration, washed with absolute ethanol, and dried to produce the pure tris(2-carbamoylethyl)phosphine oxide in 74% yield. 

Addition of a phosphorus-sulfur bond to a carbon-carbon triple bond is catalyzed by a palladium(O) complex (Equation (130)).298 Terminal aliphatic alkynes having various functional groups undergo the addition with PhS-P(0)(OPh)2 to afford (Z)-adducts in high yield. In contrast to aliphatic alkynes, phenylacetylene gives a mixture of E Z adducts. Internal alkynes and alkenes are unreactive. 

The reactivity of metal phosphide cations [MPJ+, and anions [MPJ , may also be studied in the gas phase. Laser ablation of mixtures of cobalt or nickel metal powders with red phosphorus gave a range of anions M PJ and cations [MPJ+ (185). The anions were unreactive, but the cations have been reacted with several neutral molecules. The ions [MPJ+, where M = Co, Ni and x = 2,4, 8, undergo five types of reactions. 

An attempt to prepare 1 -bromo-2-fluoroethane by the partial fluorination of ethylene dibromide by means of antimony trifluoride was not very successful. The compound was best prepared by the action of phosphorus tribromide on F.E.A. The compound was relatively non-toxic and the bromine atom rather unreactive, but considerably more reactive than the chlorine atom in chlorofluoroethane. For example, bromofluoroethane was readily converted by means of potassium thiocyanate into 2-fluoroethyl thiocyanate. As a lethal inhalant the toxicity of the thiocyanate was inferior to that of M.F.A. Toxicity by injection, however, appeared to be higher. 

The mixture does not usually become a clear solution because the product begins to crystallize. It is not difiicult, however, to recognize yellow lumps of unreacted phosphorus pentachloride. 

The second reason for acid-digestion is the determination of the total soil elemental content of, e.g. potassium, phosphorus or trace elements. This is seldom done for potassium in normal soil samples, mainly because the total K in soils is of no value as an index to the availability of K to plants, nor is it always of value in tracing the movement or accumulation of applied fertilizer K (Pratt, 1965). The unreactive soil phosphorus is obtained by subtracting the naturally leached reactive phosphorus from the total phosphorus, and a method for determining the latter by extraction with sulphuric acid and potassium persulphate is cited by Turner and FHaygarth (2000). They analysed... 

The flask and contents are placed on a steam cone and heated for 2 hours under vacuum (furnished by a water aspirator) (Note 2) in order to remove the phosphorus oxychloride formed in this process as well as most of the unreacted phosphorus pentachloride. The dry cake is pulverized in a mortar and transferred to a 4-1. beaker. To this is added 750 ml. of distilled water and 2 1. of chloroform. The mixture is placed on a steam bath, heated to boiling, and stirred vigorously until nearly all the solid dissolves. By means of a separatory funnel the layers are separated while still hot. The chloroform solution is again heated to boiling and filtered through a large fluted filter into an Erlenmeyer flask. 

Noltes et al. [31] have already described the reaction of diethylzinc with diphe-nylphosphane leading to organozinc-phosphorus adducts which have been shown to be very reactive but very insoluble. In our synthesis of the phosphite 45 with the nitroalkenes 46 in the presence of Et2Zn the precipitation of a solid could be observed as well, which was unreactive at -78 °C but underwent addition to the nitroalkenes at 0 °C. In the presence of TMEDA even at these low temperatures the desired Michael adducts 47 were formed with very good yields and high diastereomeric excesses (de - 84-96%) (Scheme 1.1.12). After removal of the... 

Treat the unreacted white phosphorus deposit remaining on the walls of the reaction flask with bromine water. 

There are other elements (such as boron, silicon, and phosphorus) which can form chains of atoms bonded to one another. Carbon is unique because it not only forms strong carbon-carbon bonds but also because these bonds remain strong when the carbon atoms are bonded with other elements. Carbon compounds are stable and relatively unreactive chemically. This is not true of the compounds of other chain-forming atoms. 

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