Nonionic surfactants catalysts

Figure 6.5. Molecular structures of typical crown ether and POE nonionic surfactant catalysts and complexes.

The production of alkylphenols exceeds 450,000 t/yr on a worldwide basis. Alkylphenols of greatest commercial importance have alkyl groups ranging in size from one to twelve carbons. The direct use of alkylphenols is limited to a few minor appUcations such as epoxy-curing catalysts and biocides. The vast majority of alkylphenols are used to synthesize derivatives which have appUcations ranging from surfactants to pharmaceuticals. The four principal markets are nonionic surfactants, phenoUc resins, polymer additives, and agrochemicals. 

Condensation cure can also be carried out ia emulsions (200—209). In this case, the cross-linker and polydimethylsiloxanediol are emulsified usiag anionic, cationic, or nonionic surfactants ia water, and a condensation catalyst such as dibutyltin dilaurate is added. The polymer can then undergo cross-linking, forming a continuous film when the water is evaporated. 

HTAB has been used, on the one hand, to increase the CL intensity of the reaction of 2,6,7-trihydroxy-9-(4 chlorophenyl)-3-fluorene with hydrogen peroxide in alkaline solution, in the presence of traces of Co(II) as a catalyst [43]. As a consequence, a CL method has been established for determination of ultratraces of Co(II). On the other hand, HTAB micelles sensitize the CL oxidation of pyro-gallol with A-bromosuccimide in an alkaline medium [44], while anionic and nonionic surfactants inhibit the CL intensity of this reaction (Table 3). This sensitized process allows the determination of pyrogallol by flow injection in an interval of 5 X 10 7-3 X 10 5 M. 

Homologous w-alkenecarboxylic acid methyl esters were hydroformyl-ated with the water-soluble rhodium/tppts catalyst in an aqueous-organic two-phase system (75). By addition of surfactants a micellar system was created. Cationic surfactants are better than anionic or nonionic surfactants for this hydroformylation. 

An attempt was also made to accelerate the same reaction performed in a microemulsion based on water, nonionic surfactant and hydrocarbon oil [9]. The reaction was performed in a Winsor III system and the same Q salt, tetra-butyl ammonium hydrogen sulfate, was added to the formulation. In this case the addition of the phase transfer catalyst gave only a marginal increase in reaction rate. Similar results have been reported for an alkylation reaction performed in different types of micellar media [52]. The addition of a Q salt gave no effect for a system based on cationic surfactant, a marginal increase in rate for a system based on nonionic surfactant and a substantial effect when an anionic... 

Catalysts and catalytic supports are often formulated from aluminas owing to their low cost, and their thermal, chemical and mechanical stability [27], To this end, nonionic surfactant templating with polyethylene oxide surfactants was used to synthesize mesoporous alumina [28], Partially ordered mesoporous materials with wormhole channels were obtained - this seems to be a characteristic of templating with nonionic surfactants. Cationic surfactants have recently been found to template mesoporous aluminum oxide with pore sizes that could be fine-tuned by varying the molar ratio of the reactants [29]. The material obtained was thermally stable to 900 °C and exhibited a narrow pore size distribution. 

Hydrocarboxylation of the Ce-Cs a-olefins with cobaltcarbonyl/pyridine catalysts at 200 °C and 20 MPa gives predominantly the linear carboxylic acids. The acids and their esters are used as additives for lubricants. The Ce-Cio a-olefins are hydroformylated to odd-numbered linear primary alcohols, which are converted to polyvinylchloride (PVC) plasticizers with phthalic anhydride. Oligomerization of (preferably) 1 -decene, applying BF3 catalysts, gives oligomers used as synthetic lubricants known as poly-a-olefins (PAO) or synthetic hydrocarbons (SHC) [11, 12]. The C10-C12 a-olefins can be epoxidized by peracids this opens up a route to bifunctional derivatives or ethoxylates as nonionic surfactants [13]. 

Well ordered mesoporous silicate films were prepared in supercritical carbon dioxide.[218] In the synthesis in aqueous or alcoholic solution, film morphology of preorganized surfactants on substrate cannot be fully prescribed before silica-framework formation, because structure evolution is coincident with precursor condensation. The rapid and efficient preparation of mesostructured metal oxides by the in situ condensation of metal oxides within preformed nonionic surfactants can be done in supercritical CCU- The synthesis procedure is as follows. A copolymer template is prepared by spin-coating from a solution containing a suitable acid catalyst. Upon drying and annealing to induce microphase separation and enhance order, the acid partitions into the hydrophilic domain of the template. The template is then exposed to a solution of metal alkoxide in humidified supercritical C02. The precursor diffuses into the template and condenses selectively within the acidic hydrophilic domain of the copolymer to form the incipient metal oxide network. The templates did not go into the C02 phase because their solubility is very low. The alcohol by-product of alkoxide condensation is extracted rapidly from the film into the C02 phase, which promotes rapid and extensive network condensation. Because the template and the metal oxide network form in discrete steps, it is possible to pattern the template via lithography or to orient the copolymer domains before the formation of the metal oxide network. 

When a mixture of butadiene and methyl methacrylate is heated at 90 °C with an aqueous suspension of kraft wood pulp containing a small amount of nonionic surfactant and in the absence of a catalyst, essentially equimolar alternating butadiene-methyl methacrylate copolymer is grafted on the cellulose when the monomer charge contains 20-50 mole % methyl methacrylate (21). 

Rhodium complexes generated from the polyethylene glycol)-functionalized phosphine 9 (n = 1, x = 0, R = Me, Bu), which should behave as a nonionic surfactant and be able to induce micelle formation, have been used as catalysts in the hydroformylation of 1-dodecene in an aqueous/organic two-phase system [31]. The conversion of 1-dodecene was 80% and the n/iso ratio 60 40, with no carryover of the rhodium catalyst into the organic phase. The Rh/9 (n = 1, x = 0, R = Me, Bu) catalyst remained active after one recycle step [31],... 

The nonionic surfactant, the chiral diphosphine 33, was used to modify Rh catalysts for the hydrogenation of the prochiral alkene (Z)-methyl a-acetamidocinna-mate in aqueous and organic media [60], Only in water did the catalyst Rh/33 give the expected increase in enantioselectivity (91% ee) [60],... 

Some other C—C bond coupling reactions in micellar systems should be mentioned here. Monflier et al. [72] described, in both papers and patents, the telome-rization of 1,3-butadiene into octadienol in a micellar system by means of a palladium-phosphine catalyst. Water-soluble and amphiphilic phosphines have been used and the surfactants were widely varied. The authors have shown that the promoting effect of surfactants appeared above the CMCs of the surfactants, and they conclude that micellar aggregates were present in the reaction mixture. Cationic, anionic, and nonionic surfactants gave this micellar effect but the combination of the highly water-soluble TPPTS and the surfactant dodecyldimethylamine hydrocarbonate was found to be best. A speculation about the location of reactants shows that the reaction probably occurs in the interface between the micellar pseudophase and water. 

The same effect of catalyst concentration (catalyst NaOH) on the distribution of EO sequences/hydroxyl groups was observed in the synthesis of nonionic surfactants of polyethoxylated fatty alcohol types. Thus, by the transformation of 60-100% of the... 

Use of a nonionic surfactant, Triton X, with a cinchonidinium based PT catalyst to accelerate the alkylation step. 

Alkylphenol ethoxylates are important kinds of nonionic surfactants. A characteristic feature of the catalytic ethoxylation of alkylphenols is the enhanced reactivity of phenol hydroxyl for ethylene oxide in comparison with alcohols. Esters of ethylene glycol and alkylphenol behave already as an alcohol. Therefore di-, tri-, and m-mers are allowed to form only after the complete consumption of the starting material. All commercial ethoxylated alkylphenols are mixtures of oligomer-homologues having a Poisson-like distribution with some PEG and catalyst as impurities. Both alkylphenols and dialkylphenols are useful for ethoxylation as a hydrophobic moiety. Among the alkylphenols, isooctylphenol and isononylphenol are most widely used. They are synthesized by the Friedel-Crafts alkylation of phenol with butene dimer and mixture of propene trimers, respectively. 

The effect of surfactants on the autooxidation of different thiols such as 2-mercaptoethanol (ME), 3-mercapto-1,2-propanediol (MPD), mercaptoacetic acid (MAAc) and dodecylmercaptan (DDM) in the presence of a polymeric catalyst, has been studied [155,156]. Fig. 20 illustrates the change in the initial rate of ME oxidation and the change in solution turbidity as a function of the concentration of the added anionic surfactant, sodium dodecylsulfate (DDS). The strong drop in the reaction rate and the increase in the turbidity of the system are apparently due to the formation of a complex between the polyion and the surfactant. However, the nonionic surfactant, oligoethylene oxide, does not influence ME oxidation. 

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