Divinyl acetals

Divinylethyl orthoacetate is prepared in 80 % yield in a similar manner by reacting ketene divinyl acetal and ethanol under acid catalysis at 0°-5°C. (See Table VI [124].)... 

Kakuchi and Yokota have reported the enantioselective cyclopolymerization of divinyl acetal and divinyl catechol using a chiral cationic initiator 31/ZnCl2 (Scheme 15) [104,105]. The resultant polymer contains only cyclic units, however the relative ratio of cis and trans rings is not reported. By comparing the CD spectra of the polymer and a model compound, it was suggested that the trans rings of the polymer were predominantly of one absolute configuration. 

Although they lack commercial importance, many other poly(vinyl acetal)s have been synthesized. These include acetals made from vinyl acetate copolymerized with ethylene (43—46), propjiene (47), isobutjiene (47), acrylonitrile (48), acrolein (49), acrylates (50,47), aHyl ether (51), divinyl ether (52), maleates (53,54), vinyl chloride (55), diaHyl phthalate (56), and starch (graft copolymer) (47). 

Heitz et al. (33) also described the preparation of polyvinyl acetate cross-linked with butanediol divinyl ether. The polymer is the base of the Merckogel series of size exclusion chromatography packings, and its hydrolyzed derivative, polyvinyl alcohol, is marketed as Fractogel and Toyopearls. 

If the condensation proceeds far enough, a network structure is easily formed. Similarly, copolymerization of a little divinyl adipate with vinyl acetate yields a nonlinear polymer in which chains of bifunctional vinyl acetate units are bridged, or cross-linked, by the tetrofunctional divinyl adipate units, as indicated on the following page, where the divinyl adipate unit is enclosed between vertical dashed lines ... 

Polyvinyl alcohols may be applied as such or in crosslinked form [90]. Crosslinkers can be aldehydes (e.g., formaldehyde, acetaldehyde, glyoxal, glutaraldehyde), to form acetals, maleic acid or oxalic acid to form cross-linked ester bridges, or others (e.g., dimethylurea, polyacrolein, diisocyanate, divinyl sulfonate) [89,91]. 

Chromatography by ion exchange on a sulfonated poly(styrene-co-divinyl benzene) phase has been proposed as a replacement for titrimetry.57 Eluted by a dilute solution of a neutral salt such as sodium ethanesulfonate, the conductance of the protons can be measured in the absence of a suppressor from sub-millimolar to molar concentration. The response factors of mono-, di-, and trichloroacetic acid and of o-phthalic acid were large and essentially equivalent to ethanesulfonic acid, while the response factor of acetic acid was far smaller. A syringe pump has generated pressures as high as 72,000 psi (5000 bar) in a capillary column packed with 1 p particles, generating a fraction capacity of 300 peaks in 30 minutes.58... 

Reaction of 2-formylbenzoic acids with 1, 1-bisdialkylaminoethylenes in acetic anhydride has been found91 to yield phthalides such as 21. These color formers are claimed to yield blue to green images, but have also been described92 as intermediates for the preparation of divinyl phthalides by a route identical to that described in Scheme 3, for which they are probably of more significance. (See Section 4.6.2.)... 

The aza-[2,3] Wittig rearrangement of aziridines is an excellent method for the synthesis of substituted piperidines. The analogous reaction of an epoxide has recently been examined <06TL7281>. Reaction of divinyl epoxide 48 with /-butyl diazo acetate provides the ylide intermediate 49, which then undergoes the [2,3] Wittig rearrangement to 50, Several catalysts were examined as catalysts for the formation of 49. It is noteworthy that the copper catalyst performed much better than the more widely used rhodium catalysts. 

The reaction is reversible and therefore the products should be removed from the reaction zone to improve conversion. The process was catalyzed by a commercially available poly(styrene-divinyl benzene) support, which played the dual role of catalyst and selective sorbent. The affinity of this resin was the highest for water, followed by ethanol, acetic acid, and finally ethyl acetate. The mathematical analysis was based on an equilibrium dispersive model where mass transfer resistances were neglected. Although many experiments were performed at different fed compositions, we will focus here on the one exhibiting the most complex behavior see Fig. 5. 

TLC separation of the components of black dye commercial product (BDCP) was performed on silica layers. The chemical structures of the dye components are shown in Fig. 3.17. Dyes were extracted from the effluent of the dye processing plant, from the untreated river water and from the drinking water treatment plant. The organic extracts were further concentrated and purified using a copolymer of styrene divinyl benzene. The mobile phase for TLC separation consisted of toluene-ethyl acetate (8 1, v/v). The Rp values of dye components were 0.43 (C. I. Disperse Violet 93), 0.48 (C. I. Disperse Orange 37) and 0.59 (C. I. Disperse Blue 373), respectively. 

DIHYDROFURAN DIVINYL ETHER METHACROLEIN 2-BUTYNE-1,4-DIOL ganna-BUTYROLACTONE cis-CROTONIC ACID trans-CROTONIC ACID METHACRYLIC ACID METHYL ACRYLATE VINYL ACETATE ACETIC ANHYDRIDE SUCCINIC ACID DIGLYCOLIC ACID MALIC ACID TARTARIC ACID n-BUTYRONITRILE ISOBUTYRONITRILE ACETONE CYANOHYDRIN... 

Methylenebis(oxy) ]bis(2-chloroformaldehyde), see Bis (2-chloroethoxy) methane Methylene chlorobromide, see Bromochloromethane Methylene dichloride, see Methylene chloride Methylene dimethyl ether, see Methylal Methyl 2,2-divinyl ketone, see Mesityl oxide Methylene glycol, see Formaldehyde Methylene glycol dimethyl ether, see Methylal Methylene oxide, see Formaldehyde Methyl ethanoate, see Methyl acetate (1 -Methylethenyl)benzene, see a-Methylstyrene Methyl ethoxol, see Methyl cellosolve 1-Methylethylamine, see Isopropylamine (l-Methylethyl)benzene, see Isopropylbenzene Methylethyl carbinol, see sec-Bntyl alcohol Methyl ethylene oxide, see Propylene oxide ds-Methylethyl ethylene, see cis-2-Pentene frans-Methylethyl ethylene, see frans-2-Pentene Methyl ethyl ketone, see 2-Bntanone Methylethylmethane, see Butane... 

The first case is the copolymerization of monomer A with diene BB where all the double bonds (i.e., the A double bond and both B double bonds) have the same reactivity. Methyl methacrylate-ethylene glycol dimethacrylate (EGDM), vinyl acetate-divinyl adipate (DVA), and styrene-p- or m-divinylbenzene (DVB) are examples of this type of copolymerization system [Landin and Macosko, 1988 Li et al., 1989 Storey, 1965 Ulbrich et al., 1977]. Since r = Yi, Fi = f and the extent of reaction p of A double bonds equals that of B double bonds. There are p[A] reacted A double bonds, p[B] reacted B double bonds, and p2[BB] reacted BB monomer units. [A] and [B] are the concentrations of A and B double bonds,... 

By-products formed during their preparation (e.g., ethylbenzene and divinyl-benzenes in styrene acetaldehyde in vinyl acetate) added stabilizers (inhibitors) autoxidation and decomposition products of the monomers (e.g., perox-... 

In a closely related investigation, designed to generate vinyl alcohol in solution, divinyl hemiorthoformate [68] was detected as an intermediate in the hydrolyses of divinyloxymethyl dichloro- and trichloro-acetate [67] (Capon et al., 1981b). It is interesting that methyl vinyl hemiorthoformate could not be detected in the hydrolysis of methoxyvinyloxymethyl acetate and chloroacetate under similar conditions. So dimethyl and divinyl hemiorthoformate appear to be more stable than methyl vinyl hemiorthoformate. 

A Du Pont patent (2) describes a colorless, viscous polyacetal from the divinyl ether of 1, 5-pentanediol and subsequent acetalization. This product can be used for cross-linking polyvinyl alcohol films. 

The literature reports direct grafting by gamma-rays exposure of Nylon fibers or films to the following monomers carbon monoxide (/65), ethylene (157), propylene (157), acetylene (166), butadiene (157.162,163), styrene (158, 161,163,167,168), vinyl chloride (157,163), vinyl fluoride (169-172), vinyl acetate (161,163,173), vinyl propionate (161), vinyl butyrate (161), vinyl crotonate (161), vinyl 2-ethyl hexanoate (161), acrylic add (173,174), methyl acrylate (162, 163), ethyl acrylate (162,163), allyl acrylate (163), methyl methacrylate (28,161, 163,164), butyl methacrylate (161), acrylamide (158), methylol acrylamide (163), acrylonitrile (157,160-163, 167, 175-179), divinyl sulfone (161), vinyl pyridine (167,173), vinyl pyrrolidone (28) and triallyl cyanurate (158). 

The so-called trimerization of propynal in the presence of piperidine acetate provides a synthesis of 4-ethynyI-4//-pyran-3,5-dicarbaldehyde (149) (50LA(568)34> it should be noted that the structure proposed for the product in the original work has been corrected (64CB1959). In the absence of moisture, the reaction fails and it seems likely that the synthesis involves hydration of the alkyne to the divinyl ether. Finally, condensation with the third molecule of the aldehyde results in cyclization to the product (Scheme 20). 

Some supporting evidence for the mechanism is provided by the formation of the 4-ethyl analogue (150) when propynal is treated with piperidine acetate in the presence of propanal the latter may be considered to intercept the divinyl ether. 

Much milder conditions are used in the double Michael addition approach, in which a divinyl ketone is condensed with hydrogen sulfide in mildly basic medium (equation 77) (77JOC2777). Enol acetates (R1 = MeCC>2) may be used, and the product obtained then contains a 2-mercapto function (R1 = SH see also equation 82) (59% yield). Although this is a very versatile synthesis, its biggest drawback is the lability of simple divinyl ketones, and phenyl substitution at position 2 is frequently used to overcome this. 

Very recently examples of tandem Michael-azomethine ylide cyclization reactions have been presented.626 Thus, divinyl sulfone reacted with imine (124) in the presence of lithium bromide and tri-ethylamine to give (126) in 40% yield (Scheme 38). Presumably formation of Michael adduct (125), tau-tomerization to an azomethine ylide and ensuing intramolecular [3 + 2] cycloaddition afforded (126). Indeed, (125) could be independently synthesized and converted to (126) under the reaction conditions. The preference for initial Michael addition, rather than cycloaddition, was variable. When (124) and divinyl sulfone were treated with silver acetate and triethylamine in DMSO, intermolecular azomethine cycloaddition occurred giving (127) in 27% yield. 

Membrane materials often employed are hydrophobic polysulfone or hydrophilic regenerated cellulose or cellulose acetate other materials are nylon, polytetrafluoro-ethylene (PTFE, Teflon), polyether ether ketone (PEEK) or poly(divinyl fluoride) (PDVF). 

Fig. 3. GPC elution behavior of polyvinyl acetate gels crosslinked with different amounts of divinyl adipate...

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