Formaldehyde from styrene

Dioxanes can be efficiently synthesized from styrenes using formalin as the formaldehyde source (Prins reaction) with triflic acid as catalyst717 [Eq. (5.267)]. 

Butyrolactones are used in the synthesis of cyclopentenone derivatives 362 364). 3-Phenyl-1-propanol can be produced from styrene and formaldehyde 366). 

Sulfonic acid resin from styrene—furfural copolycondensate Sulfonic acid resin from a-pinene—furfural copolycondensate Commercial sulfonic acid resin from phenol—formaldehyde resin Commercial sulfonic acid resin from SDVB copolymer Phosphonic acid resin from PNVC Phosphonic acid resin from NVCF Phosphonic acid resin from PNVCF... 

Plastics require such a wide variety of raw materials that it is difficult to select the major petroleum chemical developments. Styrene, vinyl chloride, and polyethylene from ethylene, formaldehyde from petroleum methanol, and urea from petroleum ammonia are the chief contributions of petroleum chemicals. 

Desulfurization of petroleum feedstock (FBR), catalytic cracking (MBR or FI BR), hydrodewaxing (FBR), steam reforming of methane or naphtha (FBR), water-gas shift (CO conversion) reaction (FBR-A), ammonia synthesis (FBR-A), methanol from synthesis gas (FBR), oxidation of sulfur dioxide (FBR-A), isomerization of xylenes (FBR-A), catalytic reforming of naphtha (FBR-A), reduction of nitrobenzene to aniline (FBR), butadiene from n-butanes (FBR-A), ethylbenzene by alkylation of benzene (FBR), dehydrogenation of ethylbenzene to styrene (FBR), methyl ethyl ketone from sec-butyl alcohol (by dehydrogenation) (FBR), formaldehyde from methanol (FBR), disproportionation of toluene (FBR-A), dehydration of ethanol (FBR-A), dimethylaniline from aniline and methanol (FBR), vinyl chloride from acetone (FBR), vinyl acetate from acetylene and acetic acid (FBR), phosgene from carbon monoxide (FBR), dichloroethane by oxichlorination of ethylene (FBR), oxidation of ethylene to ethylene oxide (FBR), oxidation of benzene to maleic anhydride (FBR), oxidation of toluene to benzaldehyde (FBR), phthalic anhydride from o-xylene (FBR), furane from butadiene (FBR), acrylonitrile by ammoxidation of propylene (FI BR)... 

Polymer characterization is an important use of NIR spectrometry. Polymers can be made either from a single monomer, as is polyethylene, or from mixtures of monomers, as are styrene-butadiene rubber from styrene and butadiene and nylon 6-6, made from hexamethylenediamine and adipic acid. An important parameter of such copolymers is the relative amount of each present. This can be determined by NIR for polymers with the appropriate functional groups. Styrene content in a styrene-butadiene copolymer can be measured using the aromatic and aliphatic C—H bands. Nylon can be characterized by the NH band from the amine monomer and the C=0 band from the carboxylic acid monomer. Nitrogen-containing polymers such as nylons, polyurethanes, and urea formaldehyde resins can be measured by using the NH bands. Block copolymers, which are typically made of a soft block of polyester and a hard block containing aromatics, for example, polystyrene, have been analyzed by NIR. These analyses have utilized the... 

Basic catalysts also show very different behaviour from acid catalysts for the alkylation of aromatics. Whereas acid catalysts promote alkylation of the aromatic ring, with high shape selectivity in the important case of ZSM-5 (Chapter 8), alkali metal zeolites catalyse side chain alkylation. In the case of the reaction of toluene with methanol over Cs-X, for example, the products include ethylbenzene and styrene. The side chain alkylation proceeds by the following base-catalysed steps, (i) formation of formaldehyde from methanol, (ii) activation of the toluene by polarisation of the methyl group (tending towards carbanion formation) and (iii) nucleophilic attack of the carbanion of toluene on the carboxyl group of formaldehyde. Side chain alkylation of aromatics is therefore a special case of aldol condensation. Reactions of this... 

Cylindrical carbon nanofibers are coated with thin layer of pyrolyzed carbonaceous polymer. Coating layer is comprised of one or more polymers selected from group consisting of phenolic formaldehyde, polyacrylonitrile, styrene DVB, cellulosic polymers, and H-resin. 

To identify the carbonyl compound and the ylide required to produce a given alkene mentally disconnect the double bond so that one of its carbons is derived from a car bonyl group and the other is derived from an ylide Taking styrene as a representative example we see that two such disconnections are possible either benzaldehyde or formaldehyde is an appropriate precursor... 

With each succeeding year in the 1950s and 1960s there was a swing away from coal and vegetable sources of raw materials towards petroleum. Today such products as terephthalic acid, styrene, benzene, formaldehyde, vinyl acetate and acrylonitrile are produced from petroleum sources. Large industrial concerns that had been built on acetylene chemistry became based on petrochemicals whilst coal tar is no longer an indispensable source of aromatics. 

Table 5.2 Reactivity ratios for copolymerization of p-cresyl formaldehyde oligomers with methacrylic groups (10) and styrene (2). [Reproduced from S. Polowinski, Polimery, 39, 419 (1994), with kind permission from 1. Ch. P.]...

Template copolymerization seems to be applied to the synthesis of copolymers with unconventional sequences of units. As it was shown, by copolymerization of styrene with oligomers prepared from p-cresyl-formaldehyde resin esterified by methacrylic or acrylic acid - short ladder-type blocks can be introduced to the macromolecule. After hydrolysis, copolymer with blocks of acrylic or methacrylic acid groups can be obtained. Number of groups in the block corresponds to the number of units in oligomeric multimonomer. Such copolymers cannot be obtained by the conventional copolymerization. 

The stereochemistry of the Prins reaction is complex. In the transformation of cyclohexene and 2-butenes anti stereoselective addition was observed,67-69 whereas syn addition of two formaldehyde units takes place in the formation of 1,3-dioxanes from substituted styrenes.70 Most of the transformations are, however, nonstereo-selective,71 72 accounted for by carbocation 18. 

In work reported elsewhere (31) we have shown that the oxidation of styrene under mild conditions is promoted by many group VIII metal complexes. The product profile depends on the nature of the metal center and often differs from that observed when radical initiators are used (Table IX). Substantial quantities of styrene oxide are found in some cases but not in others (31). The epoxide which is formed, however, seems to arise via the co-oxidation of styrene and formaldehyde which is formed by oxidative cleavage of the double bond. Formaldehyde may be oxidized to performic acid or formylperoxy radicals which are efficient epoxidizing agents. Reactions of styrene with oxygen in the presence of group VIII complexes exhibit induction periods and are severely retarded by radical inhibitors (31). Thus, the initial step in the oxidation of styrene in the presence of the Ir(I),Rh(I), Ru(II), and Os(II) com-... 

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