Phos pentoxide

Monosubstituted malonic anhydrides have not yielded aldoketenes, but malonic acid itself jdelds carbon suboxide when heated with phos-pho] pentoxide. ... 

Nitrogen pentoxide is obtained by dehydration of pure nitric acid by phos-phorus(V) oxide at low temperatures around -10°C ... 

Hydrates of Arsenic Pentoxide.—The existence of hydrates of arsenic pentoxide corresponding to the ortho-, meta- and pyro-phos-phorie acids has not been established. Many such products have been described in the literature, the formation of which could not be confirmed by subsequent workers.1 It appears certain that a tetrahydrate, As,05.4H20, and a (3, J)-hydrate, 3As205.5H20, exist there is also evidence of the formation of a heptahydrate, As,03. H,0. and of a dihydrate (pyroarsenic acid), As203.2H20. 

A facile method for the preparation of a variety of stabilized arsonium ylides in good yield has been developed by the action of active methylene compounds with tertiary arsine oxide or tertiary arsine dihalide. Thus triphenyl-arsine dihalides react with a number of active methylene compounds in the presence of a tertiary amine to afford arsonium ylides (6) (40). The reaction of triphenylarsine oxide with active methylene compounds in the presence of either acetic anhydride or triethylamine-phos-phorus pentoxide gave rise to arsonium ylides (6) (32, 36. 65, 67). 

Anhydrous cupric chloride is dried in an oven at 110-120° for several hours and stored in a desiccator or over pho horus pentoxide before use. 

Red phosphorus burns in the air producing a pretty yellow flame, at the top of which the white smoke of phosphorus pentoxide is generated. With this property it is used for a day and night signal. (The flame spectrum probably occurs from PHO molecules XV6436-4879 A R.W.B. Pearse and A.G.Gaydon The identification of molecular spectra, p.271, 4th edition (1976)). ... 

Cyclodehydration 1,5-Diazabicyclo[4.3.0]nonene-5. 2,3-Dichloro-5,6-dicyano-l, 4-benzo-quinone. l,l-Dichloro-2,2-difluororoethyIene. Dichloroketene. Hydrobromic acid. Phos-phoryl chloride-Phosphoric acid-Phosphorus pentoxide. Polyphosphoric acid. Thionyl chloride. 

Phosphorus pentoxide — Pho >horic anhydride— P,0 —142—is formed when P is burned in an excess of dry O. It is a white, flocculent solid, which has almost as great a tendency to combine with H.O us Las... 

Chloroform is a noncombnstible liqnid. Mixing chloroform with certain snbstances can produce explosions. This inclndes alkali metals such as sodium, potassium, or lithium finely divided magnesinm or alnminum sodium-potassinm alloy nitrogen tetroxide (Tnrley 1964) and perchloric acid-phos-phoms pentoxide (NFPA 1986). Contact with disilane may prodnce incandescence (Mel-lor 1946-1947), and with potassinm tert-bntoxide or sodinm methoxide can result in ignition (MCA 1961, 1972). 

The mixture is taken up with water and the base is extracted from the toluene with dilute hydrochloric acid. The hydrochloric solution is rendered alkaline with caustic soda, the base is separated with ether, dried, and after distillation of the ether fractionated in vacuo, BP at 0.05 mm Hg, 150° to 153°C. The basic ether is then dissolved In dry ether, and ether saturated with dry hydrogen chloride is added dropwise with stirring. An excess of hydrogen chloride must be avoided as it may produce decomposition to the corresponding diphenyl ethylene. The ether.moist hydrochloride is preferably dried at once in vacuo and subsequently reprecipitated from acetone.ether and then again dried in vacuo over phos. phorus pentoxide. Hydrochloride, MP 128°C. 

Reviews on the synthesis and chemistry of carbodiimides are given in [1248-1250]. Carbodiimides are mainly synthesized in one of three ways from ureas or thioureas, from isocyanates, or from isocyanides. Several reagents have been employed in carbodiimide synthesis phosgene [1252, 1253], dimethylphosgenimi-nium chloride [1254], tiiphosgene [561, 562], phosphorus pentoxide [1255], phos-phoryl chloride [1256], triphenylphosphine dibromide [758, 1257-1261], triphenylphosphine/tetrahalomethanes [1262, 1263], iminophosphoranes [1264-1277], Mitsunobu reagent [1278, 1279], p-tosyl chloride [1280, 1281], and CDC [1137] oxidative additions have also been used [1282-1284]. 

Powdered solids may be dried in a desiccator or a vacuiun oven. There are a wide variety of desiccants in common use. Materials such as phos-porus pentoxide may be used in cases in which an aggressive drying agent is required. Note that samples removed from a vacuum oven must ideally be allowed to cool in a desiccator prior to analysis otherwise, moisture can be absorbed while the sample is coohng to room temperature. 

The most important oxide of phosphoms is P4O10 (phos-phoms(V) oxide), commonly called phosphorus pentoxide. It can be made directly from P4 (eq. 15.10) or by oxidizing P4O6. In the vapour phase, phosphoms(V) oxide contains... 

Sulphur trioride acts violently on tins compound, with formation of phosphorus oxychloridt and sulphur dioxide. Heated with oonoentroted sulphuric arid, rillonisniphonic acid and pho horus pentoxide are product necoulmg to the equari[Pg.484]

Sampson and Shooter, from their study on vanadium oxide/phos-phorus pentoxide catalyzed oxidation of n-butane, suggest that there are two potential routes of MA one via crotonaldehyde and the other via butadiene. Furan has also been suggested as an intermediate in the sequence. 

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