Water-ethylene glycol catalyst

Supported liquid-phase (water-ethylene glycol) catalyst containing Pd complexes was used for hydrogenation of stilbene in toluene [57]. It was found that zeolite CaY acted, in the presence of Bronsted acid sites, either as a reagent for reducing stilbenes to 1,2-diarylethanes or as a catalyst for isomerizing cis-stilbenes to the more stable trans form [58]. In contrast, the Lewis add sites generated by the activation process yield radical cations from stilbenes, but these did not yield any stable products. 

Figure 5.28 Schematic of the experimental set-up. Water/ethylene glycol/SDS reservoir (a) high-pressure liquid pumps (b) catalyst/ substrate HPLC injection valve with 200 pi sample loop (c) hydrogen supply, equipped with mass flow controller (d) micro mixer (e) heating jacket (f) tubular glass or quartz reactor (g) back-pressure regulator (h) [64],...

Silica gels and controlled-pore glass, which were covered with thin films of polar phases such as water, ethylene glycol or ionic liquids, were used as polar solid supports. These systems are limited to very polar, usually ionic catalysts and non-polar reaction media in order to prevent catalyst leaching. This in turn, can be limiting to the range of substrates. Existing catalytic processes in common liquid-liquid biphasic systems can be easily transferred to supported liquid-phase conditions. At the same time the interfacial area between the... 

Poly (ethylene glycol)s are made by reaction of ethylene oxide with water, ethylene glycol, or diethylene or triethylene glycol using sodium or potassium hydroxide catalyst. 

CH2C1 CH2C1. Colourless liquid with an odour like that of chloroform b.p. 84 C. It is an excellent solvent for fats and waxes. Was first known as oil of Dutch chemists . Manufactured by the vapour- or liquid-phase reaction of ethene and chlorine in the presence of a catalyst. It reacts with anhydrous ethano-ales to give ethylene glycol diethanoate and with ammonia to give elhylenediamine, these reactions being employed for the manufacture of these chemicals. It burns only with difficulty and is not decomposed by boiling water. 

Ethylene glycol esterification of BHET is driven to completion by heating and removal of the water formed. PET is also formed using the same chemistry starting with dimethyl terephthalate [120-61-6] and ethylene glycol to form BHET also using an antimony oxide catalyst. 

Diol Components. Ethylene glycol (ethane 1,2-diol) is made from ethylene by direct air oxidation to ethylene oxide and ring opening with water to give 1,2-diol (40) (see Glycols). Butane-1,4-diol is stiU made by the Reppe process acetylene reacts with formaldehyde in the presence of catalyst to give 2-butyne-l,4-diol which is hydrogenated to butanediol (see Acetylene-DERIVED chemicals). The ethynylation step depends on a special cuprous... 

With Formaldehyde. The sulfuric acid cataly2ed reaction of formaldehyde [50-00-0] with carbon monoxide and water to glycoHc acid [79-14-1] at 473 K and 70 MPa (700 atm) pressure was the first step in an early process to manufacture ethylene glycol [107-21-1]. A patent (58) has described the use of Hquid hydrogen fluoride as catalyst, enabling the reaction to be carried out at 298 K and 7 MPa (70 atm) (eq. 18). 

The reaction is carried out over a supported metallic silver catalyst at 250—300°C and 1—2 MPa (10—20 bar). A few parts per million (ppm) of 1,2-dichloroethane are added to the ethylene to inhibit further oxidation to carbon dioxide and water. This results ia chlorine generation, which deactivates the surface of the catalyst. Chem Systems of the United States has developed a process that produces ethylene glycol monoacetate as an iatermediate, which on thermal decomposition yields ethylene oxide [75-21-8]. 

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. 

Scheme 3b). It is instructive at this point to reiterate that the furan nucleus can be used in synthesis as a progenitor for a 1,4-dicarbonyl. Whereas the action of aqueous acid on a furan is known to provide direct access to a 1,4-dicarbonyl compound, exposure of a furan to an alcohol and an acid catalyst should result in the formation of a 1,4-diketal. Indeed, when a solution of intermediate 15 in benzene is treated with excess ethylene glycol, a catalytic amount of / ara-toluenesulfonic acid, and a trace of hydroquinone at reflux, bisethylene ketal 14 is formed in a yield of 71 %. The azeotropic removal of water provides a driving force for the ketalization reaction, and the presence of a trace of hydroquinone suppresses the formation of polymeric material. Through a Finkelstein reaction,14 the action of sodium iodide on primary bromide 14 results in the formation of primary iodide 23, a substance which is then treated, in crude form, with triphenylphosphine to give crystalline phosphonium iodide 24 in a yield of 93 % from 14.

PET is the polyester of terephthalic acid and ethylene glycol. Polyesters are prepared by either direct esterification or transesterification reactions. In the direct esterification process, terephthalic acid is reacted with ethylene glycol to produce PET and water as a by-product. Transesterification involves the reaction of dimethyl terephthalate (DMT) with ethylene glycol in the presence of a catalyst (usually a metal carboxylate) to form bis(hydroxyethyl)terephthalate (BHET) and methyl alcohol as a by-product. In the second step of transesterification, BHET... 

Conversion to acetals is a very general method for protecting aldehydes and ketones against nucleophilic addition or reduction.245 Ethylene glycol, which gives a cyclic dioxolane derivative, is frequently employed for this purpose. The dioxolanes are usually prepared by heating a carbonyl compound with ethylene glycol in the presence of an acid catalyst, with provision for azeotropic removal of water. 

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