Ethanediol, oxidation

To analyze 1,2-ethanediol, oxidation with excess IO4 is followed by passage of the reaction solution through an anion-exchange resin that binds both IO4 and IO3. lO is then quantitatively removed from the resin by elution with NH4CI. The absorbance of eluate is measured at 232 nm to find the quantity of 10 J (molar absoiptivity (e) = 9(X) M cm ) produced by the reaction. In one experiment, 0.213 9 g of aqueous 1,2-ethanediol was dissolved in 10.(X) mL. Then 1.000 mL of the solution was treated with 3 mL of 0.15 M KIO4 and subjected to ion-exchange... 

Since double bonds may be considered as masked carbonyl, carboxyl or hydroxymethylene groups, depending on whether oxidative or reductive methods are applied after cleavage of the double bond, the addition products from (E)-2 and carbonyl compounds can be further transformed into a variety of chiral compounds. Thus, performing a second bromine/lithium exchange on compound 4, and subsequent protonation, afforded the olefin 5. Ozonolysis followed by reduction with lithium aluminum hydride gave (S)-l-phenyl-l,2-ethanediol in >98% ee. 

Several results were reported by Russian authors. They are completely different from those reported above. Sorokin14 found an overall reaction order of 2 for the system heptanoic acid/l,2-ethanediol/diphenyl oxide. Bolotina16 studied the reaction of 2-ethylhexyl hydrogenphthalate with 2-ethylhexanol in the corresponding diester and found an order of 1 with respect to acid and of 2 with respect to alcohol. 

Habid and Malek49 who studied the activity of metal derivatives in the catalyzed esterification of aromatic carboxylic acids with aliphatic glycols found a reaction order of 0.5 relative to the catalyst for Ti(OBu)4, tin(II) oxalate and lead(II) oxide. As we have already mentioned in connection with other examples, it appears that the activation enthalpies of the esterifications carried out in the presence of Ti, Sn and Pb derivatives are very close to those reported by Hartman et al.207,208 for the acid-catalyzed esterification of benzoic and substituted benzoic acids with cyclohexanol. These enthalpies also approach those reported by Matsuzaki and Mitani268 for the esterification of benzoic acids with 1,2-ethanediol in the absence of a catalyst. On the other hand, when activation entropies are considered, a difference exists between the esterification of benzoic acid with 1,2-ethanediol catalyzed by Ti, Sn and Pb derivatives and the non-catalyzed reaction268. Thus, activation enthalpies are nearly the same for metal ion-catalyzed and non-catalyzed reactions whereas the activation entropy of the metal ion-catalyzed reaction is much lower than that of the non-catalyzed reaction. 

Fig. 12.4. Successive models of the transition state for Sharpless epoxidation. (a) the hexacoordinate Ti core with uncoordinated alkene (b) Ti with methylhydroperoxide, allyl alcohol, and ethanediol as ligands (c) monomeric catalytic center incorporating t-butylhydroperoxide as oxidant (d) monomeric catalytic center with formyl groups added (e) dimeric transition state with chiral tartrate model (E = CH = O). Reproduced from J. Am. Chem. Soc., 117, 11327 (1995), by permission of the American Chemical Society. 

Preparation of diols Acid-catalysed epoxides are easily cleaved by water. Water reacts as the nucleophile, and this is referred to as a hydrolysis. For example, hydrolysis of ethylene oxide in the presence of acid-catalyst produces 1,2-ethanediol (ethylene glycol). 

Ethanediol (ethylene glycol) [5g] Commercial products are pure enough for most purposes. In order to remove water of 2000 ppm, the ethanediol is dehydrated with sodium sulfate anhydride and distilled twice at reduced pressure in a dry nitrogen atmosphere in order to avoid oxidation to aldehyde. 

Oxidation of 2-methoxyethanol or 1,2-ethanediol by [0s04], in the presence of a porphyrin, is used to prepare [Osn(P)(CO)(X)] complexes [P is a porphyrinato(2-) ligand] (139). Recently, more convenient preparations of porphyrinato complexes were developed using the reactions of LOs3(CO)i2] with the appropriate porphyrin (Section II,C,4,d) (38, 40, 140,141). Electrochemical studies show that both the Os(III) and Os(III)/porphyrin-cation-radical complexes are moderately stable... 

Polymers usually are prepared by two different types of polymerization reactions — addition and condensation. In addition polymerization all of the atoms of the monomer molecules become part of the polymer in condensation polymerization some of the atoms of the monomer are split off in the reaction as water, alcohol, ammonia, or carbon dioxide, and so on. Some polymers can be formed either by addition or condensation reactions. An example is polyethylene glycol, which, in principle, can form either by dehydration of 1,2-ethanediol (ethylene glycol), which is condensation, or by addition polymerization of oxacyclopropane (ethylene oxide) 1... 

C. Wandrey, and U. Kragl, Enzymic resolution of 1-phenyl-1,2-ethanediol by enantioselective oxidation overcoming product inhibition by continuous extraction, Biotechnol. Bioeng. 1996, 51, 544-550. 

Three cyclic initiators from dibutyltin oxide and 1,2-ethanediol, 2-mer-captoethanol, and 1,2-dimercaptoethane as indicated in Fig. 43 were prepared. Polymerizations of L-lactide and racemic D,L-lactide were conducted... 

Set up the equations required for solution of Example 15.13 by the method of equilibrium constants. Verify that your equations yield the same equilibrium compositions as given in the example. 1541 Ethylene oxide as a vapor and water as liquid, both at 25°C and 10133 kPa, react to form an aqueous solution of ethylene glycol (1,2-ethanediol) at the same conditions ... 

The ligand was then used to form a variety of transition metal carbene complexes [207] (see Figure 3.72). Interestingly, more than one method for the formation of transition metal carbene complexes was successfully employed presence of an inorganic base (IC COj) to deprotonate the imidazolium salt and the silver(I) oxide method with subsequent carbene transfer to rhodium(I), iridium(I) and copperfi), respectively. The silver(I) and copper(I) carbene complexes were used for the cyclopropanation of styrene and indene with 1,1-ethanediol diacetate (EDA) giving very poor conversion with silver (< 5%) and qnantitative yields with copper. The diastereomeric ratio (endolexo) was more favonrable with silver than with copper giving almost a pnre diastereomer for the silver catalysed reaction of indene. 

Periodic acid is a versatile oxidant since, depending on pH, the redox potential for the periodate-iodate couple varies from 0.7 V in aqueous basic media to 1.6 V in aqueous acidic media.Based on this observation, Villemin and Ricard devised an oxidative cleavage of glycols, in which mcjo-l,2-diphenyl-1,2-ethanediol was oxidized by periodic acid on alumina to benzaldehyde in 82% yield in aqueous ethanol (90% ethanol) at room temperature in 26 h. The same supported oxidant converted aromatics into quinones. In the presence of transition metal complexes (Mn ), a-arylalkenes suffer oxidative cleavage to aldehydes. For example, tran.r-stilbene gives benzaldehyde at room temperature. 

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