Phosphorus Isocyanates

Abstract

Compounds containing the PNCO grouping can be obtained e.g. from phosphorus halides and silver cyanate or esters of N-chloroiminocarbonic acid and by thermal decomposition of alkoxycarbonylimino-phosphoranes. The phosphorus( vj isocyanates resemble the "carbon" isocyanates in their chemical properties, whereas the phosphorus(rrrj isocyanates resemble the phosphorus(mj chlorides. Some of the compounds discussed have insecticidal or cytostatic actions.

Reactive Flame Retardants for Polyurethane Foams

“…Direct attachment of isocyanate groups to phosphorus has received little attention for flame retardants in polyurethane foams, although most of the various possible derivatives are reported. A recent review concerned with the preparation and chemistry of triand quinquevalent phosphorus isocyanates of this series has been published (235).…”

Oxygen-, nitrogen-, and sulfur-substituted heteroallenes

“…Another route leading to amino isocyanates 149 is the pyrolysis of 1,1-dialkylcarbazates 150 in the presence of phosphoric acid catalyst at 200 °C.126 Under these conditions the initially formed aminimides 151 or 152 respectively convert to 1,2-dimethyl-4-substituted-triazolidinediones 155 or 156 (R1 = 0), or the 1,2,4-triazolidin-3-one-5-thiones 156 (R1 = S) when an isothiocyanate is present in the pyrolysis mixture.126 This Stevens-type rearrangement132 is known to occur in other molecules containing a similar betaine-type moiety133•134 and has been realized for other amino isocyanate adducts as well.126•127•129 A closely related reaction is the pyrolysis of 1-alkylsemicarbazides (158); the products obtained were believed to be the triazolidinediones 161.135 This could involve an intermediate monosubstituted alkylamino isocyanate 159. Finally, 1-phenylcarbazate 160 eliminates ethanol upon heating and the same type of compound, 161, has been Isolated. 136 A very elegant method of generating amino isocyanates 149 is based on the facile thermal reversibility of the cycloaddition product of amino isocyanates 149 and bulky isocyanates, i.e., when a bulky substituent is attached to position 4 lidine derivative 152 such as R' = ferf-butyl124 or ferf-octyl.126 Thus, when 152a or h are heated to above 60°t hey dissociate to their parent compounds. The amino isocyanates 149a,h dimerize to the aminimides 151a,h when no other reactive substrate is present, although, in the presence of other isocyanates, isothiocyanates (as seen above124•125•130), carbodiimides,124 acetylenes137 or cyanates,138 cycloaddition with these partners can compete effectively with dimerization.…”

“…Thus, Nmethyldiazoacetamide )1), upon photolysis in water, gives hydroxymethylacetamide (3) and AAmethylglycine (5) in a ratio 2:1. 7 The intermediate carbene 2 can be trapped by the solvent but undergoes, in part, a Wolff rearrangement to methylaminoketene (4) which is hydrolyzed to the amino acid derivative. Similarly, small amounts (18%) of methyl /,/V-diethylglycinate (8) have been isolated when /V./V-diethyldiazoacetamide (6) was photolytically decomposed in methanol, its formation involving a ketene intermediate 7 Photolysis and thermolysis of ethyl diazomalonanilate (9) in various alcohols yield considerable amounts of «-/V-phenylaminomalonic esters 13.9 A possible mechanism could involve migration of the phenylamino group to give a ketene intermediate 11. Since no ketene species could be trapped (e.g., with styrene), an alternative mechanism could involve formation of an -lactam intermediate 12 by carbene 10 N-H insertion.…”

Spectroscopic Properties, Conformation and Structure of Difluorothiophosphoryl Isocyanate in the Gaseous and Solid Phase

“…[9] Furthermore, some α-oxo-isocyanates like phosphoryl isocyanates, R 2 P(O)NCO, show physiological activity and find applications in insecticides and drugs. [10] Dichlorophosphanyl isocyanate (Cl 2 PNCO) [11] and dichlorophosphoryl isocyanate [Cl 2 P(O)NCO] [12] is the only complementary pair of phosphorus(III) and phosphorus(V) compounds bearing isocyanate groups that has been characterized so far, spectroscopically and structurally, both in the solid state as well as in the gas phase. Quantum-chemical calculations predict synand anti-conformations for both phosphorus compounds in the different oxidation states with barriers to interconversion lower than 3 kJ mol À 1 .…”