Single-stage synthesis of alkyl-H-phosphinic acids from elemental phosphorus and alkyl bromides

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Reactions of elemental phosphorus and phosphine with electrophiles in superbasic systems: XX. Phosphorylation of 4-vinylbenzyl chloride with elemental phosphorus

4-Vinylbenzyl chloride reacts with white and red phosphorus, as well as with nanostructured “activated” red phosphorus (complex organophosphorus polymer prepared from white phosphorus under ionizing radiation) in the system concentrated aqueous KOH-dioxane-phase-transfer catalyst (20–50°C, argon) to form tris(4-vinylbenzyl)phosphine oxide, along with (4-vinylbenzyl)- and bis(4-vinylbenzyl)phosphinic acids, the yield and product ratio being dependent on both the reaction conditions and the nature of the phosphorylating agent. The nanostructured “activated” red phosphorus is more reactive than ordinary commercial red phosphorus.     

Reactions of elemental phosphorus and phosphine with electrophiles in superbasic systems: XVIII. Phosphorylation of 1-(chloromethyl)naphthalene with the elemental phosphorus

1-Chloromethylnaphthalene reacts with white and red phosphorus, and also with the “activated red phosphorus,” the complex organophosphorus polymer of unknown structure obtained by irradiation of a solution of white phosphorus in benzene by the ⁶⁰Co source, in a system including KOH water solution, dioxane or benzene, and a phase transfer catalyst (22–98°C, argon), to form bis(1-naphthylmethyl)-and tris-(1-naphthylmethyl)phosphine oxides, and also (1-naphthylmethyl)phosphonous-and bis(1-naphthylmethyl)-phosphinic acids. The yield and the ratio of the reaction products depend on reaction conditions as well as on the nature of phosphorylating agent. It is shown that the reactivity of the “activated red phosphorus” is not worse than that of the white phosphorus and significantly exceeds the reactivity of the usual technical red phosphorus.     

Synthesis of highly sterically hindered niobium and tantalum alkoxides and their microhydrolysis in strongly basic medium

We have investigated the interaction of niobium and tantalum alkoxides with pinacol and are reporting here isolation and structural characterization of the products, attractive potential precursors of materials with hierarchical porosity. The general feature in the reactivity of alkoxide complexes with additional ligands is that stabilization of the complexes is achieved due to Brønsted acidity of the ligand and possibility of formation of hydrogen bonds in the structure. Presence of strong organic bases does not influence the complex formation. We were able to isolate, for example, highly moisture-sensitive ortho-pinacolates of Nb and Ta, M(O₂C₆H₁₂)₂(OC₆H₁₂OH), in the presence of excess of triethylamine. The earlier attempts to prepare these complexes were unsuccessful because of extremely high solubility and easy hydrolysis of these species. The first step in microhydrolysis of M(O₂C₆H₁₂)₂(OC₆H₁₂OH), M = Nb, Ta, independently of basicity of the medium provides M₂O(O₂C₆H₁₂)₂(OC₆H₁₂OH)₄, even those highly moisture-sensitive in solution. The general conclusion of this work is that the Lewis acidity and blocking of the coordination sites by bulky alkoxide ligands does not play any important role. The reactivity of the species is not in any way hindered by the complete blocking of the metal centers.     

Synthesis of alkyl-H-phosphinic acid alkyl esters from red phosphorus and alkyl bromides

Alkyl-H-phosphinic acid alkyl esters are synthesized in 65–71% yield via chemoselective reaction of alkyl bromides with available alkyl-H-phosphinic acids (60–65 °C, Et3N). The latter are prepared, in turn, by direct phosphorylation of alkyl bromides with red phosphorus under phase-transfer conditions.     

Reaction of elemental phosphorus with phenols

Conclusions The composition and yield of the products formed upon the reaction of elemental phosphorus with phenols depends on the acidity of the phenol and the nature of the ring substituent. The phenol pK_a range, in which the reaction of elemental phosphorus with phenols is possible, is 9–11.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2632–2634, November, 1988.     

Reaction of elemental phosphorus with epoxides

Conclusions The reactions of P₄/propylene oxide/Me₃N/HX (mole ratio=150.81) leads to the formation of an oligomer. The chain of this oligomer features the sequence of -C-P(O)-O-fragments. Features were determined which control the rate of P₄ conversion depending on the composition of the reaction mixture. The oligomer composition was determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1399–1402, June, 1987.     

Synthesis of organophosphorus compounds based on the reaction of elemental phosphorus with proton-donor reagents

Russian Journal of General Chemistry - Reaction of elemental (white) phosphorus with proton-donor reagents has been studied. The following organophosphorus compounds containing P-O and P-S bonds...     

Concerning electronegativity as a basic elemental property and why the periodic table is usually represented in its medium form

Electronegativity, described by Linus Pauling described as “The power of an atom in a molecule to attract electrons to itself” (Pauling in The nature of the chemical bond, 3rd edn, Cornell University Press, Ithaca, p 88, 1960), is used to predict bond polarity. There are dozens of methods for empirically quantifying electronegativity including: the original thermochemical technique (Pauling in J Am Chem Soc 54:3570–3582, 1932), numerical averaging of the ionisation potential and electron affinity (Mulliken in J Chem Phys 2:782–784, 1934), effective nuclear charge and covalent radius analysis (Sanderson in J Chem Phys 23:2467, 1955) and the averaged successive ionisation energies of an element’s valence electrons (Martynov and Batsanov in Zhurnal Neorganicheskoi Khimii 5:3171–3175, 1980), etc. Indeed, there are such strong correlations between numerous atomic parameters—physical and chemical—that the term “electronegativity” integrates them into a single dimensionless number between 0.78 and 4.00 that can be used to predict/describe/model much of an element’s physical character and chemical behaviour. The design of the common and popular medium form of the periodic table is in large part determined by four quantum numbers and four associated rules. However, adding electronegativity completes the construction so that it displays the multi-parameter periodic law operating in two dimensions, down the groups and across the periods, with minimal ambiguity.     

Phosphorylation of five-membered aromatic heterocycles with phosphorus tribromide

Phosphorus trichloride in a basic medium is a convenient reagent for the direct C-phosphorylation of electron-rich aromatic heterocycles. The compounds obtained can be used for the synthesis of various types of heteroaryl and diheteroaryl derivatives of tri- and pentavalent phosphorus. © 1995 John Wiley & Sons, Inc.     

Phosphorylation of trihydroxybenzenes with the trivalent phosphorus derivatives

Phosphorylation of the simplest trihydroxybenzenes and their acylated derivatives with the trivalent phosphorus reagents of cyclic and acyclic structure was discussed. A possibility of the selective phosphorylation of acylated trihydroxybenzene derivatives was demonstrated. A dismutation was detected, leading to dimers of the linear structure containing a variety of phosphorus-containing fragments of different nature.