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Phosphonites cyclic

Propanesultone also forms random and alternating copolymers with N-substituted ethylenimines276) and similar mechanisms involving zwitter ions were suggested. The polymerization through zwitter ions was performed with cyclic phosphonite as the Mn monomer and pyruvic acid as the ME monomer250). [Pg.23]

Other monomers that have been studied include cyclic phosphonites and phosphites as well as some sulfur analogs and nitrogen derivatives [Baranetal., 1989 Kobayashietal., 1986]. [Pg.600]

The concept of no catalyst copolymerization has demonstrated its usefulness in the exploration of phosphorus-containing polymers. For example, the cyclic phosphonite 34 was successfully copolymerized both with p-propiolactone (31) and acrylic acid 35). These copolymerizations proceed via a common zwitterion 36 and hence produce the same copolymer 37. [Pg.85]

The cyclic phosphonite (2) reacts with aromatic cyclic disulfides in acetonitrile to produce a sulfiir-containing phosphorane. The system is reversible and the direction depends on the nature of the solvent. In acetonitrile, the phosphorane (3) precipitates. But in other solvents such as benzonitrile, chloroform, methylene dichloride, benzene or THF, the reverse reaction takes place and is complete overnight at room temperature. The practical interest of this reaction is quite limited as it occurs only with one phosphonite (2). ... [Pg.96]

The dioxaphosphinane ring is preserved on reaction of the cyclic phosphite (334) with methyl iodide the methanephosphonate diester (335) is the only product <64X2781 >. Similar treatment of the 2-phenyl derivative (336), a cyclic phosphonite, does cleave the ring, to form the iodopropyl phosphinate (337) with C—O fission <79JOC1060>. The ring is also opened when the cyclic phos-phonate ester (338) reacts with PhMgBr here the P—O bond is broken (Scheme 68) <67X283>. [Pg.1064]

The rhodium(I)-catalyzed reduction of ketones with silanes is also subject to enantioselection by chiral ligands, which can be a bipyridine derivative, cyclic phosphonites and phosphites, " or diferrocenyl dichalcogenides. ... [Pg.92]

Reactions between cyclic phosphonites (58) and alkyl halides have been employed to prepare linear (ring-opened) polymeric phosphonates which, when heated more strongly, undergo depolymerization and furnish l,2-oxaphosph(V)olanes, e.g. 59 when R = H, a second product has been shown to be the phosphinic anhydride (60) ... [Pg.61]

Cyclic phosphonites react with catechol according to (6.500), and butadiene according to (6.501). A pentaoxyphosphorane is produced by a reaction between PCI5 and tartaric acid. [Pg.397]

Dialkyl esters of 3,3 -thiodipropionic acid (52), cyclic phosphonites such as neopentylphenyl phosphite, derivatives of phosphaphenathrene-lO-oxide (53), secondary aromatic amines such as diphenylamine (54), and epoxidized soybean oils (55) are effective stabilizers for preventing discoloration of cellulose esters during thermal processing. [Pg.1106]

Treatment of l-hydro-5-carbaphosphatrane (33) with oxidants such as 3-chloroper-oxybenzoic acid and /BuOCl gave the cyclic phosphonate (34) and l-chloro-5-carbaphosphatrane, respectively, via a cyclic phosphonite, a tautomer of (33, R = H) (Scheme 9). l-Chloro-5-carbaphosphatrane was readily hydrolyzed to afford (34, X = O). Compound (33, R = H) was also sulfurized via by elemental sulfur to afford cyclic thioxophosphonate (34, X = S), which was also obtained by reactions in the presence of bases. Treatment of (33, R = H) with bases also proceeded to give an equilibrium mixture of the corresponding phenoxide anion (35) and the phos-phoranide anion (36), which was quenched with Mel to afford a mixture of 1-methyl-5-carbaphosphatrane (33, R = Me) and (37). Such reactivity is typical of neutral phosphoranes. Theoretical investigations of this reactivity were also performed. ... [Pg.252]

Scheme 1 Michaelis-Arbuzov (M-A) type of rearrangement in cationic polymerization of cyclic phosphonites. Scheme 1 Michaelis-Arbuzov (M-A) type of rearrangement in cationic polymerization of cyclic phosphonites.
In the case of copolymerization of vinylphosphonic acid monoethyl ester (92) with cyclic phosphonites (86), the alternating copolymer (93) having two kinds of phosphorus atoms in the main chain was formed. During the copolymerization, monomer 92 was reduced involving a hydrogen-transfer process and monomer 86 was oxidized the oxidation state of the phosphorus atom of monomer 86 changed, therefore, from trivalent to pentavalent ( oxidation-reduction copolymerization ). ... [Pg.491]

A series of rhodium(l) complexes [RhClL (nbd)] (L = chiral cyclic phosphonite with a fused 1,4-dioxane or cyclobutane ring in the backbone) was synthesized via the corresponding borane-phosphonite adducts. ... [Pg.207]

Star polymers having three, four, and six arms were prepared by the ring-opening polymerization of six-membered cyclic phosphonite (1) initiated with a catalyst system of NiBr2 and polyhalobenzenes [19,20]. Various polyhaloben-zenes (1,3,5-trihalobenzenes (2a,b), 1,2,4,5-tetrahalobenzenes (3a-c), and hexahalobenzenes (4a-c)) were employed as multifunctional initiators to give star-shaped polymers having three, four, and six arms, respectively (Scheme 1). [Pg.108]


See other pages where Phosphonites cyclic is mentioned: [Pg.851]    [Pg.37]    [Pg.42]    [Pg.239]    [Pg.275]    [Pg.68]    [Pg.311]    [Pg.311]    [Pg.37]    [Pg.64]    [Pg.947]    [Pg.962]    [Pg.963]    [Pg.963]    [Pg.139]    [Pg.57]    [Pg.261]   
See also in sourсe #XX -- [ Pg.4 ]




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