Poly reaction procedures

The immobilization of catalysts or catalyst precursors on solid supports is a common technique for simplifying reaction procedures and/or increasing the stability of the catalyst. The homogeneous MTO catalyst can be transformed into a heterogeneous system in a number of different ways. In a recent approach by Saladino and coworkers, poly(4-vinylpyridine) and poly(4-vinylpyridine) //-oxides were used as the catalyst carrier. The MTO-catalyst obtained from 25% cross-linked poly(4-vinylpyridine) with divinylbenzene proved to catalyze efficiently the formation of even hydrolytically sensitive epoxides in the presence of aqueous hydrogen peroxide (Scheme 11). The catalyst could be recycled up to 5 times without any significant loss of activity. 

Three component coupling reactions of aldehydes or ketones, amines, and elemental sulfur - called Willgerodt-Kinder reactions - are used to synthesize various thioamides, although the protocol of this reaction was reported over 80 years ago. However, the reaction procedure has been developed. For example, the reaction of dialdehydes, diamines and sulfur was investigated for the preparation of poly thioamides 12 (Eq. 1) [12]. 

Vegetable oil-based poly(ester amide)s are prepared by a three-step reaction procedure in which a base such as sodium methoxide is used as the catalyst for the first two steps and metal oxide/hydroxide is used for the last step of the reaction (Fig. 5.2). In the first step, methyl esters of the fatty acids are produced by transesterifiction of oil with methanol, followed by transformation to dihydroxy fatty amide by amidation reaction with dihydroxyalkylamine and, finally, esterification reaction by treatment with dibasic acid or anhydride at a relatively high temperature to obtain the desired poly (ester amide). This may be done either by azeotropic distillation or by direct polycondensation under an inert atmosphere. Poly(ester amide) can also be synthesised at a low temperature through a condensation polymerisation reaction in the absence of an organic solvent. In this reaction, V,V-bis(2-hydroxyalkyl) fatty amide and dibasic anhydride are heated at a temperature lower than the onset of the melting points of the component. By-products, such as water, are removed by a vacuum technique. 

In siunmary, a three-step reaction procedure was employed to attach RGD-containing peptides onto a titanium surface. First, water-vapor-plasma-pretreated titanium surfaces were silanized with (3-aminopropyl)-triethoxysilane in dry toluene, resulting in a multilayer film of poly(3-aminopropyl)siloxane. Second, the free primary amino groups were linked to one of the three hetero-cross-hnkers AI-succinimidyl-6-maleimidylhex-anoate, iV-succinimidyl-3-maleimidylpropionate, and N-... 

Reaction procedures to obtain poly[(oligoethylene glycol) dihydroxytitanate] (I) and poly[(oligoethylene glycol) dihydroxytitanate]/LiCI complex (II) reproduced from Munchow ef al. (2000) by permission of Elsevier. 

Chlorosilanes were used applying an identical reaction procedure to prepare either quaterarm pol)miers of type ABCD or 4- miktoarm polymers of type A2B2. A, B, C, D correspond to PS, PBd, PI, and poly(4-methylst5n ene), respectively [33]. That method was extended recently to well-defined poly(iso-prene)/poly(butadiene) A2B2 copolymers [34]. The presence on the same nodu-lus of chains exhibiting different chemical structures leads to original solution properties. Roovers et al. [35] have examined in detail the solution properties and compared the specific behavior of these miktoarm star-shaped polymers to linear diblock copolymers. That strategy was extended to the preparation of... 

Di- and poly-halogenated aliphatic hydrocarbons. No general procedure can be given for the preparation of derivatives of these compounds. Reliance must be placed upon their physical properties (b.p., density and refractive index) and upon any chemical reactions which they undergo. 

HydrophobicaHy Modified, Ethoxylated Urethane. HEUR associative thickeners are in effect poly(oxyethylene) polymers that contain terminal hydrophobe units (66). They can be synthesized via esterification with monoacids, tosylation reactions, or direct reaction with monoisocyanates. There are problems associated with aH of the methods of synthesis. The general commercial procedure for their synthesis is by a step-growth addition of... 

Ak2o has been iastmmental ia developiag a new process for the stereospecific synthesis of 1,4-cyclohexane diisocyanate [7517-76-2] (21). This process, based on the conversion of poly(ethylene terephthalate) [25038-59-9] circumvents the elaborate fractional crystallisation procedures required for the existing -phenylenediamine [108-45-2] approaches. The synthesis starts with poly(ethylene terephthalate) (PET) (32) or phthaUc acid, which is converted to the dimethyl ester and hydrogenated to yield the cyclohexane-based diester (33). Subsequent reaction of the ester with ammonia provides the desired bisamide (34). The synthesis of the amide is the key... 

Trilialophenols can be converted to poly(dihaloph.enylene oxide)s by a reaction that resembles radical-initiated displacement polymerization. In one procedure, either a copper or silver complex of the phenol is heated to produce a branched product (50). In another procedure, a catalytic quantity of an oxidizing agent and the dry sodium salt in dimethyl sulfoxide produces linear poly(2,6-dichloro-l,4-polyphenylene oxide) (51). The polymer can also be prepared by direct oxidation with a copper—amine catalyst, although branching in the ortho positions is indicated by chlorine analyses (52). 

The two-step poly(amic acid) process is the most commonly practiced procedure. In this process, a dianhydride and a diamine react at ambient temperature in a dipolar aprotic solvent such as /V,/V-dimethy1 acetamide [127-19-5] (DMAc) or /V-methy1pyrro1idinone [872-50-4] (NMP) to form apoly(amic acid), which is then cycHzed into the polyimide product. The reaction of pyromeUitic dianhydride [26265-89-4] (PMDA) and 4,4 -oxydiani1ine [101-80-4] (ODA) proceeds rapidly at room temperature to form a viscous solution of poly(amic acid) (5), which is an ortho-carboxylated aromatic polyamide. 

When B2H6 is to be used as a reaction intermediate without the need for isolation or purification, the best procedure is to add Et20Bp3 to NaBH4 in a poly ether such as diglyme ... 

Tsuda156 reported the preparation of poly(vinyl 2-furylacrylate) by the reaction of 2-furylacrylyl chloride with poly(vinylalcohol) in NaOH-water-methyl ethyl ketone. Up to 80% of the hydroxyl groups were esterified. The interest of this technique is obvious here, considering that the vinyl ester of 2-furylacrylic acid does not polymerize119 A similar procedure was employed by Gandini and Rieumont26,1 9 for the synthesis of poly(vinyl 2-furoate) another product unobtainable via a standard polymerization process (see Section 1II-B-3). 

In the sol-gel procedure for the preparation of hybrids, polymeric acid catalysts such as poly (styrene sulfonic acid) were also used instead of hydrogen chloride [14]. The polymeric acid catalyst was effective for the preparation of hybrids at a similar level to that of hydrogen chloride catalyst. In some cases, the increased modulus was observed due to the higher extent of reaction. No difference was observed in morphologies between the hybrids prepared with polymeric and small molecule acid catalysts. The method using polymeric acid catalyst may depress the ion-conductive property, characteristic to the mobile acidic small molecules. Polymeric catalyst may also influence the rheology of the resulting hybrids. 

Maleic anhydride, 98 g (1.0 mol), 148 g (1.0 mol) of phthalic anhydride, and 160 g (2.1 mol) of 1,2-propanediol are poly condensed in a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a distillation head connected to a condenser and a receiver flask. The flask is placed in a salt bath preheated at 160°C. Water begins to distill and the temperature is then raised gradually to 190°C. The polycondensation is stopped (after about 15 h) when the reaction mixture has an acid number of 50 (see Section 2.3.8.4.1) (Scheme 2.54). A slightly different procedure is described in ref. 423. 

The SnAt reactions were first successfully used in the synthesis of high-molecular-weight poly(arylene etherjs by Johnson et al.4,5 This reaction represents a good example for poly(ether sulfonejs in general, either in laboratory -or industrial-scale preparations. In this procedure, the bisphenol A and sodium hydroxide with an exact mole ratio of 1 2 were dissolved into dimethyl sulfoxide (DMSO)-chlorobenzene. The bisphenol A was converted into disodium bisphenolate A, and water was removed by azeotropic distillation. After the formation of the anhydrous disodium bisphenolate A, an equal molar amount of 4,4,-dichlorodiphenyl sulfone (DCDPS) was added in chlorobenzene under anhydrous conditions and the temperature was increased to 160°C for over 1 h... 

A great variety of suitable polymers is accessible by polymerization of vinylic monomers, or by reaction of alcohols or amines with functionalized polymers such as chloromethylat polystyrene or methacryloylchloride. The functionality in the polymer may also a ligand which can bind transition metal complexes. Examples are poly-4-vinylpyridine and triphenylphosphine modified polymers. In all cases of reactively functionalized polymers, the loading with redox active species may also occur after film formation on the electrode surface but it was recognized that such a procedure may lead to inhomogeneous distribution of redox centers in the film... 

Illustrative Procedure 2 Poly(iminocarbonates) by Solution Polymerization (46) Under argon, 1 g of a diphenol and an exact stoichiometric equivalent of a dicyanate were dissolved in 5 ml of freshly distilled THF. 1 mol% of potassium tert-butoxide was added, and the reaction was stirred for 4 hr at room temperature. Thereafter, the poly(iminocarbonate) was precipitated as a gumUke material by the addition of acetone. The crude poly(iminocarbonate) can be purified by extensive washings with an excess of acetone. The molecular weight (in chloroform, relative to polystyrene standards by GPC) is typically in the range of 50,000-80,000. 

Perhaps the most interesting finding of our synthetic studies was that the interfacial preparation of poly(iminocarbonates) is possible in spite of the pronounced hydrolytic instability of the cyanate moiety (see Illustrative Procedure 3). Hydrolysis of the chemically reactive monomer is usually a highly undesirable side reaction during interfacial polymerizations. During the preparation of nylons, for example, the hydrolysis of the acid chloride component to an inert carboxylic acid represents a wasteful loss. 

Hollow and porous polymer capsules of micrometer size have been fabricated by using emulsion polymerization or through interfacial polymerization strategies [79,83-84, 88-90], Micron-size, hollow cross-linked polymer capsules were prepared by suspension polymerization of emulsion droplets with polystyrene dissolved in an aqueous solution of poly(vinyl alcohol) [88], while latex capsules with a multihollow structure were processed by seeded emulsion polymerization [89], Ceramic hollow capsules have also been prepared by emulsion/phase-separation procedures [14,91-96] For example, hollow silica capsules with diameters of 1-100 micrometers were obtained by interfacial reactions conducted in oil/water emulsions [91],... 

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