Glycol as medium

Diethyleue glycol as medium 18,118 20, 213, 435 Diethylene glyeol diethyl ether... 

N-glycosides 13, 73 —, isolation with salicyl-aldehyde 13,119, 458 Glycol as medium 13, 667... 

Many organic reactions can be conducted very rapidly under microwave irradiation. Microwave-induced organic reaction enhancement chemistry techniques were used for the rapid formation of an ot-benzyloxy-p-lactam (10 in Fig. 4.2) and the hydrogenolysis of its benzyloxy group on a few-gram scale in 1-5 minutes with HC02NH4 and Pd/C in ethylene glycol as the reaction medium in a domestic microwave oven.243... 

In the case of ionic liquids, these general aspects for all fluid-fluid reactions are of particular importance, since mass transfer into an ionic liquid layer is generally slower than into an organic or aqueous medium. This is because ionic liquids usually have much higher viscosities than organic solvents. The least viscous ionic liquids are somewhat similar to ethylene glycol as demonstrated in Table 7.2. However, many ionic liquids used in liquid-liquid biphasic catalysis are significantly more viscous. 

The first microwave-assisted Wolff-Kishner reduction was described by Parquet and Lin in 199763. The transformation of isatin to oxindole was performed on a small scale in a domestic microwave oven in two steps with a total reaction time of 40 s, as compared to 3—4 h if classical heating was utilised (Scheme 4.36). The first step involved the transformation of the carbonyl group into the hydrazone with 55% hydrazine in ethylene glycol and medium power microwave irradiation for 30 s. In the subsequent reduction step, KOH in ethylene glycol was used to substitute the more hazardous sodium ethoxide. The reaction mixture was irradiated for 10 s and the product was obtained in a yield of 32%. 

Ethers, such as tetrahydrofuran and 1,2-dimethoxyethane, have low dielectric constants (7.4 and 7.2, respectively), and the choice of supporting electrolyte is very limited. The ethers are difficult to reduce and are inert toward many metalorganic reagents [243] that are soluble in the ethers. Ethers are thus suitable as medium for the anodic addition of Grignard reagents to olefins [420]. Dimethoxyethane and polyethylene glycol dimethyl ethers have the ability to solvate electrons [421]. Dissociation constants for some acids and the relative strength of some bases in THE has been determined [422]. 

The aim of the present work was to develop a preparation for the vanadyl orthophosphate hemihydrate which makes use of glycols as the organic compounds able to affect its morphology these have been used as additional components, besides isobutanol, in the reducing medium. A further aim of the present work was to understand which are the key aspects in the thermal treatment through the control of which is it possible to transfer morphological features of the precursor to the vanadyl pyrophosphate, and thus to finally affect the catalytic performance. 

An investigation on the kinetic aspects of hydroformylation of 1-hexene using water soluble Rh-TPPTS complex catalyst in a biphasic medium using ethylene glycol as a cosolvent is presented. The effect of reaction parameters such as, partial pressure of CO, partial pressure of hydrogen and olefin concentration on the activity were studied at 353, K. A kinetic model has also been proposed to predict the observed rate data. Condensation of heptanals with ethylene glycol led to the formation of acetal derivatives, which were isolated and characterised. 

The sample holder system used contains six sample apertures. Five samples are maximally placed at the same time in this holder to keep one aperture free for the reference measurement, see Figure 4.9. This whole sample holder system is lifted into a special thermostat bath provided with a liquid nitrogen cooling coil. This cooling possibility extends the lower temperature limit of these measurements from 20°C to about -50°C. The bath is filled with a mixture of water/ethylene glycol (l/l) for measurements between -50°C and 80°C. Silicone oil (100 cS.) is used as medium for measurements between 0eC and 200°C. The sample temperature is measured by a platinum resistance thermometer, placed as close as possible to the sample in the ultrasonic beam. 

Reproduced from Declerck V, Colacino Bantrell X, Martinez J, Lamaty F Poly(ethylene glycol) as reaction medium for mild Mzoroki-Heck reaction In a ball-mill. Chem Commun 2012 48 11778-80. With permission from the Royal Society of Chemistry. 

Low-boiling reduction products such as amines, inch deuteriated amines, and alcohols can be conveniently obtained by using a high-boiling ether, e. g. diethylene glycol diethyl ether, as medium. E. s. L. Friedman and A. T. Jurewicz, J. Org. Chem. 33, 1254 (1968). 

The organic-organic biphasic hydroformylation of hexene-1 in poly(ethylene glycol) as a polar phase, in which higher olefins are somewhat more soluble than in water, resulted in high yield, but the reaction gave rather low n / i ratio (0.75) (57). The ionic-liquid based hydroformylation of octene-1 succeeded with remarkable nii selectivities (19 1) using 7z-butyl-3-methyl-imidazolium (BMIM) trichlorostannate as the reaction medium (58). 

The process of metals electrodissolution in ionic liquids has been apvplied to develop several electropohshing procedures suitable for stainless steel, when a Type in eutectic has been involved containing ethylene glycol as the hydrogen bond donor (Abbott et al., 2004 Abbott et al., 2006) The anodic dissolution occurs in the same manner as in the case of the aqueous phosphoric and sulphuric acids electrolytes but the current efficiency was significantly improved up to about 90% and the ionic medium is much less toxic and corrosive. 

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