Ethylene glycol by oxidative

Ethylene oxide in the presence of H O can be converted to ethylene glycol by oxidation. In the process, the ring in ethylene oxide is attacked by water. Which of the following best describes the role of water ... 

C HioOj, (H0CH2CH2)20. A colourless and almost odourless liquid b.p. 244 C. Readily absorbs moisture from the atmosphere. It is obtained as a by-product in the manufacture of ethylene glycol by the hydra-lion of ethylene oxide. Manufactured by heat-... 

Ethylene glycol was originally commercially produced in the United States from ethylene chlorohydrin [107-07-3J, which was manufactured from ethylene and hypochlorous acid (eq. 8) (see Chlorohydrins). Chlorohydrin can be converted direcdy to ethylene glycol by hydrolysis with a base, generally caustic or caustic/bicarbonate mix (eq. 9). An alternative production method is converting chlorohydrin to ethylene oxide (eq. 10) with subsequent hydrolysis (eq. 11). 

Ethylene Glycol Process. Oxahc acid is also prepared by the nitric acid oxidation of ethylene glycol (15—21), and the process is basically the same as in the case of carbohydrates except for the absence of the hydrolyzer (see Eig. 1). In this process, ethylene glycol is oxidized in a mixture of... 

About 60% of the ethylene oxide produced is converted to ethylene glycol by reaction of ethylene oxide ia the presence of excess water and an acidic catalyst at 50—70°C. This is followed by hydrolysis at relatively high temperatures (140—230°C) and 2—4 MPa (20—40 bar) (see Glycols, ethylene glycol). When the water concentration is lowered, poly(ethylene glycol) is obtained. 

With Water. Wurtz was the first to obtain ethylene glycol by heating ethylene oxide and water in a sealed tube (1). Later, it was noted that by-products, namely diethjlene and triethylene glycol, were also formed in this reaction (50). This was the first synthesis of polymeric compounds of well-defined stmcture. Hydration is slow at ambient temperatures and neutral conditions, but is much faster with either acid or base catalysis (Table 8). The type of anion in the catalyzing acid is relatively unimportant (58) (see Glycols). 

Propylene glycol is produced by hydration of propylene oxide in a process similar to that for the production of ethylene glycol by hydration of ethylene oxide. 

The formation and decomposition of Crv in aqueous and non-aqueous media during the oxidation of organic substrates such as oxalic acid and ethylene glycol by potassium dichromate has been recognized for some time. No study resulted in the isolation of a stable, well-characterized chromium(V) complex until 1978 when potassium bis(2-hydroxy-2-methylbutyrato)oxochromate(V) monohydrate was prepared from chromium trioxide and the tertiary a-hydroxy acid in dilute perchloric acid according to equation (91). The Crv, which is... 

Kaverzneva, Ivanov and Salov [69] found that isopropyl alcohol, under the influence of dinitrogen tetroxide at normal temperature, is transformed into acetone. Ethylene glycol is oxidized rapidly by it to oxalic and glycolic acids. 

Although the Bonnemann method is very interesting by allowing to vary and to control easily the composition and the nanostructure of the catalyst and is adapted to the preparation of real fuel cell electrodes, it displays also some limitations. For example, bismuth-containing colloids could not be prepared with the Bonnemann method, and even in presence of platinum salts. Moreover, the presence of bismuth hinders the reduction of platinum salts [59], However, platinum-bismuth is a good catalyst for ethylene glycol electro-oxidation in alkaline medium [59-62], Moreover, colloid of tin alone could not be obtained, and the reaction was only possible by coreduction in the presence of a platinum salt. Then, other colloidal methods should be developed keeping in mind the necessity of a similar flexibility as that of the Bonnemann method. 

As an example, platinum-bismuth catalysts with different atomic ratios have been prepared by the water-in-oil method and tested for the ethylene glycol electro-oxidation in alkaline medium [59],... 

The [0s04(0H)2]2 ion has been implicated in the oxidation of ethylene glycol by 0s04 in alkali, and a mechanism proposed for this reaction involving the [0s03(0H)3(0CH2)20H]3 ion.602... 

Some terminal alkenes are oxidized to aldehydes depending on their structure. As described before, acrylonitrile and acrylate are oxidized to acetals of aldehydes in alcohols or ethylene glycol.Selective oxidation of terminal carbons in 4-hydroxy-1-alkenes (18) gave the five-membered hemiacetals (19), which can be converted to y-butyrolactones by PCC oxidation (Scheme 4). Formation of a tricyclic six-membered hemiacetal (62%) from a 5-hydroxy-1-alkene system was used for the synthesis of rosa-ramicin. Formation of aldehydes as a major product from terminal alkenes using (MeCN)2Pd(Cl)(N02) and CuCU in r-butyl alcohol under selected conditions was reported. The vinyl group in the -lactam was oxidized mainly to the aldehyde as shown below (equation 12). ... 

The next higher hydroxy acid is hydroxy acetic acid CH2(OH)— COOH, known also as glycolic acid. It may be prepared (a) from chlor acetic acid, (b) from the cyan-hydrine obtained from formic aldehyde, or (c) hy the oxidation of ethylene glycol, by reactions which have been already discussed. Its relation to ethylene glycol gives it the name of glycolic acid. It may be considered as a direct oxidation product of ethane. 

Plainly, the simplest compound which contains both alcohol and aldehyde groups is the compound derived from ethane by the oxidation of one of the methyl groups to alcohol and the other to aldehyde, or from ethylene glycol by the oxidation of one of the alcohol groups to aldehyde, viz.. 

Oxirane process. A method of making ethylene glycol by catalytic oxidation of ethylene to the diacetate, which is then hydrolyzed to ethylene glycol. 

Of more preparative value are the reactions of nucleophilic radicals, such as HOCHa and RaNCO, which can be easily generated under mild conditions, for example HOCH2 from ethylene glycol by persulfate oxidation with silver nitrate as catalyst. These substitutions are carried out on the pyridine protonic salt, which provides both increased reactivity and selectivity for an a-position the process is known as the Minisci reaction (cf. 3.4.1). It is accelerated by electron-withdrawing substituents on the ring. 

The economic data available on the production of ethylene glycol by the hydration of ethylene oxide are listed in Table 7.7. 

---