Temperature magnesium compounds

Anhydrous diethyl ether is the customary solvent used when preparing organo magnesium compounds Sometimes the reaction does not begin readily but once started It IS exothermic and maintains the temperature of the reaction mixture at the boiling point of diethyl ether (35°C)... 

The viscous magnesium compound formed is cautiously decomposed with dilute acetic acid (75 cc. in 300 cc. of water), the flask being cooled under the tap. Two clear layers are formed, and after separation, the aqueous layer is extracted with 100 cc. of ether, the combined ethereal solution is washed with water and dried with sodium sulfate, and the ether is distilled on the steam bath. The residue is distilled vmder reduced pressure. After a small fore-run the temperature rapidly rises to 130 at 10 mm. when the pure tricarbethoxymethane begins to distil. The yield of material collected over a five-degree interval is 204-215 g. (88-93 per cent of the theoretical amount). The product solidifies at 25°. The melting point of the pure substance is 28-29°. 

The hardness test sometimes is performed on the mud as well as the mud filtrate. The mud hardness indicates the amount of calcium suspended in the mud as well as the calcium in solution. This test usually is made on gypsum-treated muds to indicate the amount of excess CaSO present in suspension. To perform the hardness test on mud, a small sample of mud is first diluted to 50 times its original volume with distilled water so that any undissolved calcium or magnesium compounds can go into solution. The mixture then is filtered through hardened filter paper to obtain a clear filtrate. The total hardness of this filtrate then is obtained using the same procedure used for the filtrate from the low-temperature low-pressure API filter press apparatus. 

Seyferth prepared a-halogenoalkyl-lithium and -magnesium compounds by treating the appropriate gem-dihalides with butyllithium or with Grignard reagents at low temperature, and then used the products to prepare acyclic and cyclic a-halogenoalkyltin compounds (57-60). Typical examples are shown in the following equations. 

Although the interconversion of the ally lie isomers remains rapid at temperatures as low as —80 °C, the Schlenk equilibrium is slowed sufficiently to enable signals due to both the allyl Grignard and bis(allyl)magnesium compounds to be observed at such temperatures in their H NMR spectra. The NMR parameters for the bis(allyl)magnesium compounds are not very different from those of the Grignards, suggesting that they possess essentially... 

Wet mixes are usually dried before calcination. Calcination is performed continuously in rotary or tunnel kilns, or batchwise in directly fired drum or box furnaces. The temperature at which the mixed metal oxide pigments are formed can be reduced by adding mineralizing agents [3.75]. In the case of chromium rutile pigments, addition of magnesium compounds [3.81] or lithium compounds [3.80] before calcination improves thermal stability in plastics. 

The methyl aryl tellurium arenesulfonimides were obtained as the monohydrates. Prolonged boiling of their benzene solutions over anhydrous magnesium sulfate or drying over phosphorus pentoxide under reduced pressure did not remove the water. At higher temperatures the compounds decomposed2. 

Thermal stability. The degree to which a compound resists dissociation or other chemical alteration at elevated temperatures. Magnesium oxide is stable up to its melting point (2800° C.) and beyond, and hence is considered to have high thermal stability calcium bicarbonate decomposes at 100° to carbon dioxide, water, and calcium carbonate, and hence is thermally unstable. As used in the text, the term indicates chemical integrity up to a designated temperature. 

Magnesium oxide of high surface area can be produced by the thermal decomposition of various magnesium compounds. In the early work of Gregg and Packer (1955), a maximum specific area of about 200 m2g 1 was obtained by the calcination of Mg (OH) 2 at 380°C. This temperature was a little below the temperature required for the complete decomposition of the Mg(OH)2 under these experimental conditions. 

Alkylthiazoles react with ethylmagnesium bromide to give thiazolyl-magnesium compounds, as demonstrated for 4- and 5-methylthiazoles, 4-ethylthiazole. and 4,5-dimethyl thiazole. The resulting addition compounds do not decompose at high temperature and pressure to yield alkylthiazoles as do the addition compounds obtained with pyridine. 

The progress of the reaction with methylmethacrylate depends somewhat on initiator, temperature and solvent. Investigations have been carried out using fluorenyllithium [167, 168, 170], phenylmagnesium bromide [171, 172], butyllithium [173] and 1,1-diphenylhexyllithium [174] in toluene solution with or without the presence of ethers. Product analysis shows that two basic reactions occur with the monomer both with magnesium compounds [171, 175] and with butyllithium [176], viz. 

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