Polymerization diazomethane

Polymethylene n. A polymer first made by polymerizing diazomethane (also called... 

Polymethylene n A polymer first made by polymerizing diazomethane (also called azomethylene) (CH2N2), with evolution of nitrogen gas. While this polymer has the same formula as polyethylene, it contains no side chains, so provides a standard with which branched ethylene polymers may be compared. Although long known in the laboratory, it is not a commercial resin. 

In addition to boron-based Lewis acids, some transition metal complexes have been shown to be able to polymerize diazomethane [20, 21]. For example, Werner and Richards reported that nickelocene was highly active for polymerization of diazomethane, and proposed a polymerization mechanism where a propagating chain end contained a Ni-C bond as an active species [21]. On the other hand, when they examined a reaction of nickelocene with ethyl diazoacetate (EDA) in cyclohexene, no polymer was formed but diethyl fumarate, diethyl maleate, and ethyl norcaranecarboxylate were obtained in a 1.4 2.6 1.0 ratio (Scheme 6). 

CHR) , formed, e g. from the reaction of diazomethane and alcohols or hydroxylamine derivatives in the presence of boron compounds or with metal compounds. Poly-methylene is formally the same as polyethene and the properties of the various polymers depend upon the degree of polymerization and the stereochemistry. 

Reviews dealing with a specific reaction or property from the heterocyclic point of view have been rarer—tautomerism (continued from Volume 1), free radical substitution, metal catalysts and pyri-dines, acid-catalyzed polymerization of pyrroles, and diazomethane reactions have been covered in this volume. 

Although it is unlikely that the tetrahydrofuran ring would open under these conditions of polymerization, the polymer was hydrolyzed in 0.2 M sodium hydroxide solution, in order to confirm its structure. Clear colorless liquid was obtained after acidification followed by esterification with diazomethane. Its IR and NMR data compares exactly to that obtained from 59 which was prepared from the neutral hydrolysis of 57 and esterification of the resultant acid with diazomethane. Since the apparent sole product obtained from hydrolysis of the polymer was 59, they conclude that 58 represents the correct structure for this polymer. 

Interaction of diazomethane with bis(trimethylsilylamino)mercury gives the polymeric explosive solid. 

A similar procedure was described by Eboatu and Ferguson. An object of analysis was the complex obtained by template polymerization of acrylic acid in the presence of poly(vinyl pyrrolidone). The polycomplex was dispersed in dry benzene and treated with diazomethane. The insoluble portion was filtered. The filtrate containing poly(methyl acrylate) was concentrated and finally dried. The insoluble fraction was scrubbed with methanol to extract polyCvinyl pyrrolidone). The residue was further washed with methanol and then dried. These three portions were characterized by IR spectroscopy. It was found that only about 70% separation of the complex is achieved. The occurrence of inseparable portion is attributed to a graft copolymer formation. For the separated... 

A similar method of hydrolysis was described for poly( vinyl alcohol) used as a template. In this case, T was -CH2-CH- and, after hydrolysis, poly(vinyl alcohol) and polyacrylic or polymethacrylic acid were obtained. The hydrolyzed product gives the color reaction with I2 in the presence of H3BO3 - specific to poly(vinyl alcohol). The second product of hydrolysis, after esterification by diazomethane, was identified as polyfmethyl methacrylate) by NMR and IR spectrometry. Hydrolysis was also applied in the case of ladder-type polymers obtained by polymerization of mutliallyl monomers. The polymerization should result in polymer consisting, at least partly, ladder-type blocks ... 

After hydrolysis by 2N methanol solution of H2SO4, the product was neutralized with KOH to pH=5 and methanol evaporated. The dry residue was expected to be poly(allilamine), polymethacrylic acid, and K2SO4. Indeed, after extraction with anhydrous methanol and acetone, poly(allilamine) was identified by NMR and IR spectrometries. After evaporation, solvent from the methanol part of the extract insoluble in chloroform part was obtained. After esterification by diazomethane the product was identified as polyfmethyl methacrylate) on the basis of IR and H-NMR spectroscopy. IR spectroscopy was applied in order to examine the copolymerization of multimethacrylate (p-cresyl-formaldehyde oligomers with methacrylic groups) with st3rrene. It was found that double bond peak at 1650 cm disappeared during the process and it was absent in the product of polymerization. Polymerization and... 

Another direct approach to chiral polymeric stationary phases is the modification of commercially available polysiloxanes which contain reactive side groups. Thus, the diamide phase was linked to a modified XE-60 polysiloxane phase (Table 2). In one case (XE-60-L-Val-(/ or 5)-a-pea)124 another center of stereogenicity (R or S configuration) has been introduced in the amide group. An XE-60-L-Val-(S)-x-pea column was used for the enantiomer separation of racemic. V-rert-butoxycarbonyl amino acids after their methylation with diazomethane (serine and threonine as the O-trimethylsilyl derivatives) (Figure 12)124. 

Burets with ground-glass stopcocks should not be used, as leaking is caused by polymethylene formed preferentially on the ground surfaces. A buret such as Ultramax F and P, having a stopcock of plastic material, is satisfactory. The buret should be filled immediately before commencement of the reaction to keep the diazomethane solution cool and thus to minimize polymerization. The technique used is very similar to that of a titration, and a number of methylations of prepared batches can be quickly performed with one filling of the buret. 

Linear polyethylene can further also be considered as polymethylene. Althoguh first prepared by the thermal decomposition of diazomethane,243 244 Meerwein should be credited to have prepared it by catalytic polymerization of diazomethane effected by boron compounds (esters, halides, alkyls)245-247 taking place with concomitant dediazotation ... 

Conceivably, therefore, epoxides could form their own co-catalysts or alternatively, any trace of water could promote the formation of further hydroxyl groups. In the case of oxacyclobutane (trimethylene oxide) however the polymerization appears to involve oxonium ions yet the completely dry mixture of monomer and boron fluoride is stable, reacting only on addition of co-catalyst. It seems probable, therefore, that the formation of oxonium ions is catalysed by protons and if so, then the work of Klages and Meuresch (5) is pertinent to the present discussion. These workers found that the ether complexes of acids such as HBF4 and HSbClfi react rapidly and quantitatively with diazomethanes to yield oxonium salts... 

Es wurde festgestellt (57 a), daG hochmolekulare n-Paraffine (darge-stellt durch Polymerisation von Diazomethan) vom Molekulargewicht 20000 bis 132° C (nicht ganz klar) schmelzen. Polymere methylver-zweigte Paraffine aus Diazo-athan schmelzen bei 90 bis 100° C athyl-verzweigte aus Diazopropan bei 80 bis 90° C. 

The polymerization of cyclopropanone is initiated °) by traces of water and is inhibited 15> by moisture scavengers such as acetyl chloride. The terminal groups are apparently hemiketal units since a,co-diacetoxy-poly(oxycyclopropylidenes) 85 are isolated from a mixture of cyclopropanone hydrate, diazomethane and excess ketene. 80>... 

Partially and perfluorinated thioketones and thioaldehyde were stabilized as anthracene adducts (70). The adducts (70) were prepared in moderate yield from the corresponding carbonyl compounds with P4S10 or Lawesson s reagent in the presence of anthracene under toluene reflux. The generated thiocarbonyl compounds are not accessible in bulk due to their tendency towards polymerization. By thermolysis of the anthracene adducts (70) in the presence of C,N-bis(triisopropylsilyl)nitrilimine (NI), 1,3,4-thiadiazole derivatives (71) were obtained. Also, 1,3-dipolar cycloaddition with bis(trimethylstannyl)diazomethane (BTSD) to give consecutive products (72) from a 1,2-metallotropic migration of primary adducts was discussed. [95LA95]... 

The paint, rubber, or other polymeric sample from the organic extraction, or a new portion of the original sample is extracted with distilled, deionized water in the manner described above for an organic solvent (Figure 5, fraction 2). This sample is analyzed for polar CWC-related chemicals. For analysis with GC and GC-hyphenated techniques, the polar extract must first be derivatized an appropriate part of the extract is evaporated to dryness on a rotary evaporator at 50 °C and 366 mPa for ca. 30 min. Then 0.5 ml of acetonitrile and 0.5 ml of BSTFA are poured over the evaporation residue and the silylation mixture is heated at 60 °C for 30 min to complete the silylation (fraction 2A). This sample is analyzed for polar CWC-related chemicals such as thiodiglycol, aminoalcohols, and polar alkylphos-phonic and alkylthiophosphonic acids. The evaporation residue may also be methylated the residue is dissolved in dry acidic methanol and the solution is methylated with diazomethane. This sample is analyzed for polar alkylphosphonic and alkylthiophosphonic acids. 

Boron alkyls are expected to be inactive for coordinated anionic polymerization of olefins because the boron-carbon bond is not sufficiently ionic. The diazomethane polymerization with boron alkyl catalyst reported by Bawn, Ledwith and Matthies (275) is a special case of the growth reaction. A coordination mechanism seems most probable, but it has not been ascertained whether the polymer chain migrates as a car-banion or as a radical. If the complex between diazomethane and boron decomposes into a boron-carbene complex, then the polymer chain could migrate as a carbanion with the driving force provided by the electrophilic carbonium ion ... 

The boron trifluoride-catalyzed polymerization of diazomethane illustrates a chain-growth polymerization that is also a condensation reaction. 

The latest results on imprinted chiral footprints [154] have shown that enantioselective catalysis (hydrolysis) does occur, and based on kinetic measurement the authors believe that this is due to an enantioselective mechanism. Kaiser and Andersson also chose aluminium doped silica as a polymeric material to obtain phenanthrene imprints and their work has been discussed earlier [52]. No selectivity towards the template was observed when imprinted silica was used as stationary phase. Only relative retention and capacity factors increased. Furthermore, even after careful extraction in a Soxhlet, the polymer still leaked phenanthrene. They also found that diazomethane yields a side reaction forming long alkyl chains. Finally they attempted to rej at the work of Morihara et al. [150-155]. but were not able to detect any selectivity using dibenzamide as the template and instead found that the template decomposes into at least five different products when adsorbed on the silica. Clearly further work is required on these systems. 

Deuteration of arenes, 206 Deuterium, role in nmr, 243 Dextrorotatory, 70 Diastereomers, 69 conformational, 80 Diastereoselective reactions, 91 Diazine, 458, 460 Diazomethane, 67, 353 Diazonium ions, 409 Diazonium salts, 416 Dicarboxylic acids, 342 Diels-Alder reaction, 154 Dienes, polymerization, 153j summary of chemistry, 154 Dienophile, 154 Dihalides, dehalogenation, 91 Dimethyl sulfoxide (DMSO), 305 Dioxane, 285 Dioxin, 447... 

The surface acidity of zeolites appears to be an important ingredient for polymerization of acetylene and derivatives. Thus, when diazomethane was used to remove the protonic acidic sites on HZSM-5, no evidence for acetylene polymerization remained, compared to the original acidic form. ... 

The preparation of labeled polyalkylidenes is another example . Polyalkyl-idenes are hydrocarbon polymers of the f CH(R)4n type formed by polymerization or copolymerization of diazoalkanes RCHN2 they are of interest as model polymers Polyalkylidenes of various structures containing LM (Table 1, LMg) can be obtained by copolymerization of diazomethane (or its mixture with other diazoalkanes) and 9-anthryldiazomethane . ... 

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