Diethyl carbonate purification

Both the hydrazine hydrate and diethyl carbonate were British Drug Houses Ltd. or Matheson Laboratory reagent grade and were used without further purification. 

Utilization of dialkyl carbonates such as a DMC and diethyl carbonate (DEC) allows operation under much milder conditions, with reduced steps and waste. Taking industrial feasibihty into account, the use of dialkyl carbonates as carbonate sources is reasonable, as the alcohol by-products are easily separated, enabhng simple purification of the desired GC. Urea also has been employed as an easy-to-use source. 

The standard composition of an electrolyte in LlBs is a mixture of cycUc carbonates (such as ethylene carbonate (EC) and propylene carbonate (PC)) and chain carbonates (such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC abbreviated as MEC below), and diethyl carbonate (DEC)), to which about 1 mol/L of a lithium salt (such as lithium hexafluorophosphate (LiPF )) is added. Ube Industries, Ltd. discovered that if small amounts of impurities exist in the electrolyte, decomposition current generated from the impurities begins to flow, which leads to the formation of undesirable thick SET This spurred the development of a pioneering high-grade purification process for the base electrolyte in 1997 [16]. High purity is a key feature of functional electrolytes developed by Ube Industries, Ltd. and enables production of transparent and chemically stable electrolytes, in contrast to the conventional electrolytes which were less stable and brown owing to its low purity (Fig. 3.1). 

The present method offers several advantages over earlier methods. The use of carbon tetrachloride instead of diethyl ether as solvent avoids the intrusion of certain radical-chain reactions with solvent which are observed with bromine and to a lesser degree with chlorine. In addition, the potassium bromide has a reduced solubility in carbon tetrachloride compared to diethyl ether, thus providing additional driving force for the reaction and ease of purification of product. The selection of bro-... 

Sodium methoxide, 3-methyl-4-nitroanisole, diethyl oxalate, 30% hydrogen peroxide, 97% sodium hydride, methyl acetoacetate, sodium sulfate, 10% palladium on activated carbon, ammonium formate, and 2-nitrophenylacetic acid were purchased from Aldrich Chemical Company, Inc., and were used without further purification. 

The contents of the flask should not be heated to a temperature higher than 90° during removal of the excess oxalate or some decomposition of the product may result. The recovered diethyl oxalate contains small amounts of ethanol and ethyl carbonate. It can readily be purified by fractional distillation however, it is quite suitable for reuse in repeat preparations without purification. 

Lanthanum nitrate, analysis of anhydrous, 5 41 Lead (IV) acetate, 1 47 Lead(II) 0,0 -diethyl dithiophos-phate, 6 142 Lead (IV) oxide, 1 45 Lead(II) thiocyanate, 1 85 Lithium amide, 2 135 Lithium carbonate, formation of, from lithium hydroperoxide 1-hydrate, 5 3 purification of, 1 1 Lithium chloride, anhydrous, 6 154 Lithium hydroperoxide 1-hydrate, 5 1... 

Tolmetin, an anti-inflammatory drug, and its metabolites were chromatographed after esterification of the carboxyl group with diazomethane [564], The extraction was performed with diethyl ether and was followed by purification and analysis on 3% of OV-17. The determination of pethidine in plasma [565] involves extraction, purification of the extract by partition chromatography and derivatization, which is performed by treatment with trichloroethyl formate in the presence of anhydrous sodium carbonate. The detection limit with an ECD was reported to be 5 pg. 

Twenty-one grams (0.225 mol) of phenol is dissolved in 150 ml. of dioxane, and 5.1 g. (0.222 mol) of sodium is added. The mixture is boiled under reflux in a 500-ml. round-bottomed flask until all the sodium is dissolved. Ten grams (0.0215 mol) of octachlorocyclotetraphosphaza-tetraene is added slowly to the cold solution and the mixture is boiled for 3 hours. The cold mixture is diluted with 300 ml. of diethyl ether, then placed in a separatory funnel and washed with 120 ml. of water. It is then washed successively with dilute aqueous solutions of hydrochloric acid (5%) and sodium hydrogen carbonate (5%), and again with water. The solution is dried over sodium sulfate and the solvents are evaporated. The crude product solidifies slowly and melts at about 56°. The yield is 17 g. (85%). Purification is effected by one recrystallization from a benzene-petroleum ether mixture m.p. 85 to 86°. Anal. Calcd. C, 62.3 H, 4.3 N, 6.1. Found C, 62.0 H, 4.3 N, 6.0. 

D. (RM+ -DiphenylphosphinyM -methoxy-hl -binaphthyl (5). A 250-mL round-bottomed flask is charged with crude 4, 5.55 g (40.2 mmol) of potassium carbonate (K2C03), and 66 mL of acetone. To this mixture is added 2.5 ml. (40.2 mmol) of methyl iodide (Mel) (Note 17). The reaction mixture is refluxed for 3 hr. After the reaction is cooled to room temperature it is filtered through a Celite pad (Note 18), and the filter cake is washed with diethyl ether (EtgO). The filtrate is concentrated under reduced pressure to give 6.88 g of 5 as a brown powder (Note 19). This crude material is carried on to the next step without purification, assuming 100% yield. 

Ultra-violet and visible spectrophotometry can be effectively used for the control of purification and specification of purity of compounds. If a compound is transparent in the near ultra-violet and the visible regions, the purification is continued until the absorbancy is reduced to a minimum (e < 1). Traces of impurities present in pure transparent organic compounds can be readily detected and estimated, provided the impurities themselves have fairly intense, absorption bands. Before a liquid is used as a spectroscopic solvent, it should be tested for spectrophotometric purity. For example, commercial absolute alcohol usually contains benzene as impurity. The absence of benzene in the Alcohol should be confirmed spectrophoto-metrically by using sufficiently large cells (4 or 10 cm cells), before using the alcohol as a solvent. The presence of carbon disulphide in carbon tetrachloride may be detected by the presence of the disulphide absorption tend at 318 mytt. The detection of the characteristic benzenoid absorption in the spectra of many organic compounds (e.g. diethyl ether, cyclohexene) showed that the bands attributed to these compounds earlier were only due to the contamination by benzene1. 

Purification of carbon nanotubes has been performed in multimode [31] and monomode [32] systems. Prato purified HIPCO carbon nanotubes in a multimode oven. Common impurities are amorphous carbon and iron particles. The raw material was soaked in diethyl ether to obtain a more compact material. After evaporation of the solvent the flask was subjected to microwave heating (80 W) and an immediate weight loss occurred (5 s). This process was then repeated. Results from iron analysis were 16% (iv/iv) for the first run and 9% wjw) after the second heating cyde. It is clear in this instance that the microwave heating is selectively directed to the iron particles. It can be seen from Fig. 5.12 that, although the quality of the tubes remained similar to the original material, most of the iron spots had disappeared. 

Material Low ammonia type centrifuged NR latex from Cikumpai Rubber Plantation, PTP XII, Bandung, West Java, was used (Table 1). Carbon tetrachloride and normal butyl acrylate were used as sensitizer. Calcium nitrat was used as coagulant, and zinc diethyl Nocract 300 as antioxidant All the chemical were technical grade without further purification. 

Potassium ethoxide was prepared from 1.95 g potassium and 9.2 mL absolute ethanol in 150 mL anhydrous ether. To this mixture 14.6 g diethyl oxalate was added. After 15 min, a solution of 13.5 g ethyl (3Lmethoxy-2-biphenylyl)-acetate in 50 mL dry ether was added, and the mixture was refluxed for 51 h. The reaction mixture was cooled and extracted with 5% sodium hydroxide solution. The aqueous layer was saturated with carbon dioxide, and the precipitated oil was taken up in ether. Evaporation of the ether solution afforded 10.6 g crude diethyl Q -keto-Q -(3-methoxy-2-biphenylyl)-succinate, which was used in subsequent experiments without purification. From the alkali-insoluble fraction, 4.2 g ethyl (3 -methoxy-2-biphenylyl)-acetate was recovered. 

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