Polycondensation Of Methyl Research Articles

Preparation, properties, and structure of polysiloxanes by acid-catalyzed controlled hydrolytic co-polycondensation of polymethyl(methoxy)siloxane and polymethoxysiloxane

Polysiloxanes were prepared by acid-catalyzed controlled hydrolytic co-polycondensation of polymethyl(methoxy)siloxanes (PMS) and polymethoxysiloxanes (PMOS) obtained as macromonomers by acid-catalyzed controlled hydrolytic polycondensation of methyl(trimethoxy)silane and tetramethoxysilane, respectively. Co-polycondensation of the macromonomers with molecular weights M w 2000 (PMS) and 400 (PMOS) provided polymethylsiloxane copolymers with molecular weights M w 6500–15,000. The structure was confirmed to consist of block copolymers poly(PMS-block-PMOS) based on the results of gel permeation chromatography, isolation by fractional precipitation with THF and hexane, and 1H and 29Si NMR spectral analyses. The copolymers were soluble in organic solvents, except for hexane, and were fairly stable to self-condensation even without an end block. Transparent and flexible free-standing films were obtained from a 20 wt% THF solution of polymers. The surface morphology of films by FE-SEM and IR microscopic spectral analyses revealed cross-shaped crystalline materials on the film surface of poly(PMS-block-PMOS); these materials consisted of silsesquioxane unit structures depending on the compositions of PMS and PMOS. Polysiloxanes were prepared by acid-catalyzed controlled hydrolytic co-polycondensation of polymethyl(methoxy)siloxanes (PMS) and polymethoxysiloxanes (PMOS). The structure was confirmed to consist of block copolymers poly(PMS-block-PMOS). The surface morphology of transparent and flexible free-standing films revealed cross-shaped crystalline materials on the film surface of poly(PMS-block-PMOS); these materials consisted of silsesquioxane unit structures depending on the compositions of PMS and PMOS.

1,3,5-Trimethyl-1,3,5-tris(hexafluoroalkyl)cyclotrisiloxanes. Basicity of ethoxysilanes and cyclosiloxanes

1,3,5-Trimethyl-1,3,5-tris(hexafluoroalkyl)cyclotrisiloxanes were synthesized by hydrolytic polycondensation of methyl(hexafluoroalkyl)dichlorosilanes, and 1,1,3,3,5-pentamethyl-5-(trifluoromethyltrifluorobicyclo[2.2.1]heptyl)cyclotrisiloxane was synthesized by heterofunctional condensation. The effect of hexafluoroalkyl substituents at the silicon atom on the reactivity of the siloxane bonds has been studied.

Synthesis of macrocyclic and linear oligomers of methyl a-D-mannopyranoside

The polycondensation of methyl α-D-mannopyranoside (I) with 1,x-bis(2-formylphenoxy)alkanes (II) using various acid catalysts leads to the formation of macrocyclic compounds [1+1] and [2+2] and linear copolymer. NMR and ESI-MS studies demonstrated the evidence of structure of macrocyclic compounds. The structure of dialdehyde, the nature of the catalyst, and in particular, the molar ratio of catalyst to dialdehyde, show a very pronounced effects on yield of the resulting macrocycles.

The formation of macrocyclic compounds with O,O- and O,N-acetal units

Poly(acetal)s are prepared in polycondensation of methyl a-D-mannopyranoside (IX) and terephthalaldehyde (IV) or 1,4-bis(formylphenoxy)butanes (XIV) catalyzed by acid. The composition highly depends on the reaction conditions, structure of comonomers and nature of catalyst leading to the formation of chiral macrocycles and linear macromolecules. The regioselective polycondensation was examined by 1H NMR spectroscopy. The structures of polycondensation products were also identified by electrospray mass spectrometry (ESI-MS) and MALDI-TOF mass spectroscopy. The polycondensation of terephthalaldehyde with 2-amino-2-hydroxymethyl-1,3-propanediol [or 2,2'(1,4-phenylene)-bis-1,3-(4,4-dihydroxymethyl)oxazolidine (bis-oxazolidine)] and 2-amino-2-methyl-1,3-propanediol under acidic catalysts leads to the formation of macrocyclic compounds. ESI-MS measurements were used to study the details of polymer structure and support the nature of oxazolidine-acetal and 2-(1',4'-phenylene)-5-methyl-1-aza-3,7-dioxabicyclo[3.3.0]octane as the repeating units in all macromolecules (both cyclic and linear).

Convenient Method of Chain‐Growth Polycondensation for Well‐Defined Aromatic Polyamides

AbstractSummary: For the convenient synthesis of well‐defined poly(N‐octyl‐p‐benzamide)s with low polydispersities, the polycondensation of methyl 4‐octylaminobenzoate (1) was investigated. Methyl ester monomer 1 polymerized with lithium 1,1,1,3,3,3‐hexamethyldisilazide (LHMDS) in the presence of an initiator in tetrahydrofuran at −10 °C. The highly pure polyamide with a defined molecular weight and a low polydispersity is obtained after simple treatment of the reaction mixture with aqueous NaOH solution, followed by evaporation.The chain‐growth polycondensation of 4‐octylaminobenzoic acid methyl ester (1) with lithium 1,1,1,3,3,3‐hexamethyldisilazide (LHMDS) to yield poly(N‐octyl‐p‐benzamide).magnified imageThe chain‐growth polycondensation of 4‐octylaminobenzoic acid methyl ester (1) with lithium 1,1,1,3,3,3‐hexamethyldisilazide (LHMDS) to yield poly(N‐octyl‐p‐benzamide).

Synthesis of functional polymers with acetal‐monosaccharide moieties

AbstractThe polycondensation of methyl α‐D‐mannopyranoside (1) with 1,n‐bis(formylphenoxy)alkanes (2), using acidic catalysts, leads to the formation of linear polymers and macrocyclic compounds. The structure of the polymer and macrocycles was determined by 1H, 13C NMR spectroscopy and ESI‐MS analysis.

Condensation and Polycondensation of Terephthaldehyde with MethylD-Hexopyranosides

The condensation and polycondensations of terephthaldehyde (1) and methyl D-hexopyranosides (gluco-, galacto- and mannopyranoside) are described. Methyl α-D-glucopyranoside and methyl α-D-galactopyranoside react with 1 to give mono-5 a and 6 a and diacetals 5 b and 6 b. Their structures were confirmed by NMR and IR spectroscopy. The polycondensation of methyl α-D-mannopyranoside (4) with 1 was studied in various solvents within the temperature range of 80–140°C. Regardless of the conversion or the initial comonomer feed ratios the composition of polycondensates depended on the reaction conditions leading to the formation of materials with diverse solubilities, molecular weights and optical properties. The regioselective polycondensation of 1 and 4 was examined by the 1H NMR spectroscopy of polymer 7. In the case of five-membered cyclic acetal units, mixtures of the endo-H and exo-H dioxolan-2-yl system diastereomers are formed. Experimental examples of functionalization via ester units in polymer molecules 8 are described and the efficiency of the reaction routes and procedures are evaluated. The molecular weight was estimated by size-exclusion chromatography (SEC) measurements before and after the functionalization.

Condensation and Polycondensation of Terephthaldehyde with Methyl D-Hexopyranosides

The condensation and polycondensations of terephthaldehyde (1) and methyl D-hexopyranosides (gluco-, galacto- and mannopyranoside) are described. Methyl α-D-glucopyranoside and methyl α-D-galactopyranoside react with 1 to give mono-5 a and 6 a and diacetals 5 b and 6 b. Their structures were confirmed by NMR and IR spectroscopy. The polycondensation of methyl α-D-mannopyranoside (4) with 1 was studied in various solvents within the temperature range of 80–140°C. Regardless of the conversion or the initial comonomer feed ratios the composition of polycondensates depended on the reaction conditions leading to the formation of materials with diverse solubilities, molecular weights and optical properties. The regioselective polycondensation of 1 and 4 was examined by the 1H NMR spectroscopy of polymer 7. In the case of five-membered cyclic acetal units, mixtures of the endo-H and exo-H dioxolan-2-yl system diastereomers are formed. Experimental examples of functionalization via ester units in polymer molecules 8 are described and the efficiency of the reaction routes and procedures are evaluated. The molecular weight was estimated by size-exclusion chromatography (SEC) measurements before and after the functionalization.

Preparation and properties of polysilsesquioxanes: Polysilsesquioxanes and flexible thin films by acid‐catalyzed controlled hydrolytic polycondensation of methyl‐ and vinyltrimethoxysilane

Preparation and properties of polysilsesquioxanes: Polysilsesquioxanes and flexible thin films by acid‐catalyzed controlled hydrolytic polycondensation of methyl‐ and vinyltrimethoxysilane

Synthesis of biodegradable polyesters by polycondensation of methyl (R)‐3‐hydroxybutyrate and methyl (R)‐3‐hydroxyvalerate

Synthesis of biodegradable polyesters by polycondensation of methyl (<i>R</i>)‐3‐hydroxybutyrate and methyl (<i>R</i>)‐3‐hydroxyvalerate

Copolyesteramides, 8. A comparison of substantially alternating 12‐oxydodecanoyl/ω‐iminoalkanoyl polyesteramides with equivalent random copolymers

AbstractThe polycondensation of methyl N‐(12‐hydroxydodecanoyl)‐ω‐aminoalkanoates (HO(CH2)11CONH(CH2)xCOOCH3) has been studied as a source of the alternating polyesteramides [O(CH2)11CONH(CH2)xCO]n, and the properties of the products compared with those of equivalent random copolymers of similar co‐unit ratio. Polymerization of the esters with x = 10 and 11 occurred straight‐forwardly, giving crystalline products with were distinguishable from the random counterparts by DSC but not by 67 MHz 13C NMR. For x = 5 the reaction was complicated by progressive partial elimination of the amide moiety as 6‐hexanolactam and by transamidation leading, for the polymer of highest amide content obtained, to an imperfect structure with ca. 76% of the sub‐units in alternating arrangement, the remainder being composed of oligoester and diamide units. This deviation from ideality has been elucidated by a study of the 13C NMR spectra of a wide range of model compounds which has yielded criteria for the recognition of oligomeric iminohexanoyl units, and by the NMR and MS examination of the products of aminolytic degradation. The results explain the multiple signals found in the 13C NMR spectra of the imperfectly alternating polymer (x = 5) and of its random analogues.

Synthesis of biodegradable polyesters by polycondensation of methyl (R)‐3‐hydroxybutyrate and methyl (R)‐3‐hydroxy‐valerate

Synthesis of biodegradable polyesters by polycondensation of methyl (<i>R</i>)‐3‐hydroxybutyrate and methyl (<i>R</i>)‐3‐hydroxy‐valerate

A Study of the products of the hydrolytic polycondensation of methyl-?-(3,4-epoxycyclohexyl) ethyldiethoxysilane by the gel filtration method

1. The fractional composition of the product of the hydrolytic polycondensation of methyl-β-(3,4epoxycyclohexyl)ethyldiethoxysilane has been studied by the gel filtration method. 2. The product of hydrolytic polycondensation consists mainly of two fractions with molecular weights of 820 and 1360 which have predominantly a cyclic structure with n=4 and more.

Hydrolytic polycondensation of methyl-?-(3,4-epoxycyclohexyl)-ethyldiethoxysilane

1. A study was made of the reaction for the hydrolysis polycondensation of methyl-β-(3,4-epoxycy-clohexyl)ethyldiethoxysilane in the media: acetone — water, toluene — water, and acetone — aqueous KOH solution. 2. Hydrolysis in homogeneous medium, in the absence of alkali, goes slowly, while in the presence of KOH the hydrolysis rate increases noticeably with increase in the KOH concentration. 3. The kinetics of the hydrolysis at different temperatures was studied and it was shown that in all cases the hydrolysis reaction obeys the first-order equation. The activation energy of the reaction for various temperature intervals was determined.