Polyethylene glycol reactions

Docusate Calcium. Dioctyl calcium sulfosuccinate [128-49-4] (calcium salt of l,4-bis(2-ethylhexyl)ester butanedioic acid) (11) is a white amorphous soHd having the characteristic odor of octyl alcohol. It is very slightly soluble in water, and very soluble in alcohol, polyethylene glycol 400, and com oil. It may be prepared directly from dioctyl sodium sulfo succinate dissolved in 2-propanol, by reaction with a methan olic solution of calcium chloride. 

Mandolini and Masci provided further information on this question quite recently by demonstrating that polyethylene glycol dibromides undergo partial hydrolysis and then cyclization in water containing Ba ions. According to the report, yields were higher in this reaction when barium cation was present than when it was absent. 

Reinhoudt, Gray, Smit and Veenstra prepared a number of monomer and dimer crowns based on a variety of substituted xylylene units. They first conducted the reaction of 1,2-dibromomethylbenzene and a polyethylene glycol with sodium hydride or potassium Z-butoxide in toluene solution. Mixtures of the 1 1 and 2 2 (monomer and dimer) products were isolated and some polymer was formed . The reaction was conducted at temperatures from 30—60° and appeared to be complete in a maximum of one hour. The authors noted that the highest yield of 1 1 cyclic product was obtained with disodium tetraethylene glycolate instead of dipotassium hexaethylene gly-colate (see also Chap. 2) . Chloromethylation of 1,3-benzodioxole followed by reaction with disodium tetraethylene glycolate afforded the macrocycle (29% yield) illustrated in Eq. (3.20). 

With the discovery of the crowns and related species, it was inevitable that a search would begin for simpler and simpler relatives which might be useful in similar applications. Perhaps these compounds would be easier and more economical to prepare and ultimately, of course, better in one respect or another than the molecules which inspired the research. In particular, the collateral developments of crown ether chemistry and phase transfer catalysis fostered an interest in utilizing the readily available polyethylene glycol mono- or dimethyl ethers as catalysts for such reactions. Although there is considerable literature in this area, much of it relates to the use of simple polyethylene glycols in phase transfer processes. Since our main concern in this monograph is with novel structures, we will discuss these simple examples further only briefly, below. 

It was noted early by Smid and his coworkers that open-chained polyethylene glycol type compounds bind alkali metals much as the crowns do, but with considerably lower binding constants. This suggested that such materials could be substituted for crown ethers in phase transfer catalytic reactions where a larger amount of the more economical material could effect the transformation just as effectively as more expensive cyclic ethers. Knbchel and coworkers demonstrated the application of open-chained crown ether equivalents in 1975 . Recently, a number of applications have been published in which simple polyethylene glycols are substituted for crowns . These include nucleophilic substitution reactions, as well as solubilization of arenediazonium cations . Glymes have also been bound into polymer backbones for use as catalysts " " . 

A number of polyethylene glycols are also available in molecular weight ranges from commercial suppliers. These are made by initiating the polymerization of ethylene oxide by hydroxide ion. The corresponding monomethyl (or monoalkyl ethers) can be made in a similar fashion by initiating the polymerization with an alcohol. The general reaction is shown below in Eq. (7.2). 

Polyethylene glycol 4000 cetanol after reaction with 8-bromomethyl-benzo-d-pyndo( 1,2-a)pynmidin-6-one stabilization > 15 d dipping solution, 10% in chloroform [291]... 

Important processes commercially used are the Selexol, the Sulfinol, and the Rectisol processes. In these processes, no chemical reaction occurs between the acid gas and the solvent. The solvent, or absorbent, is a liquid that selectively absorbs the acid gases and leaves out the hydrocarbons. In the Selexol process for example, the solvent is dimethyl ether of polyethylene glycol. Raw natural gas passes countercurrently to the descending solvent. When the solvent becomes saturated with the acid gases, the pressure is reduced, and hydrogen sulfide and carbon dioxide are desorbed. The solvent is then recycled to the absorption tower. Figure 1-1 shows the Selexol process. ... 

Similarly, esters of fatty acids and polyethylene glycols are produced by the reaction of long-chain fatty acids and ethylene oxide ... 

Neugen. Polyethylene glycol laurate used as an additive to prevent the expi reaction of Ba azide. See under Barium Diazide in Vol 1, A524-L... 

In the preparation of surfactants by the reaction of alcohols with P4Ol0 with subsequent neutralization of the partial phosphate esters with a base, the quality of the surfactants is improved by using RNEt3OH (R = Et or benzyl) in alcoholic solution as the base, by using C6 10 alcohol mixtures of hydroxyethylated C7 9 alcohols or equimolar mixtures of C6 I0 alcohols with polyethylene glycol (mol wt 200-1500) and by using a reaction temperature of 55-60°C [8]. 

Nonionic polyethylene glycol 2-hydroxyalkyl and 3-alkoxy-2-hydroxyalkyl phosphate surfactants were prepared by the reaction of a polyethylene glycol... 

The following Tables 2.1 to 2.3 summarize some examples based exclusively on thermochemical reactions on the sorbent surface which lead to the formation of fluorescent reaction products. The derivatives formed frequently remain stable for weeks [6] and the fluorescence can frequently be intensified and/or be stabilized by treatment with viscous liquids (liquid paraffin, Triton X-100, polyethylene glycol etc.). 

Polyethylene glycol (PEG) consists of repeating units of ethylene glycol forming linear or branched polymers with different molecular masses. Pegylation is the process by which PEG chains are covalently attached to lEN molecules. Pegylation confers a number of properties on lEN-a molecules, such as sustained blood levels that enhance antiviral effectiveness and reduce adverse reactions, as well as a longer half-life and improved patient compliance (Kozlowski et al. 2001). 

Multi-armed polymers with a cyclotriphosphazene core XI and XII have been synthesized from the reaction of polyethylene glycol monomethyl ethers with acid chlorides of hexakis(3,5-dicarboxyphenoxy) and hexakis(4-carboxyphe-noxy) cyclotriphosphazenes. Their complexes with LiC104 were investigated, and their maximum conductivities are reported in Table 17 [621]. 

---