Benzene ester

Polyvinyl alcohol Formamide, water Ether, alcohols, petrol, benzene, esters, ketones, hydrocarbons... 

The hydrolysis of steroid hydrogen sulphates, important to biochemists in view of the excretion of many steroid hormone metabolites as water soluble salts of hydrogen sulphates, has been studied in some detail [20,21]. It had been known for some years that ether extraction of the steroid hydrogen sulphate from acidified solutions is accompanied by hydrolysis of the sulphate in the ether phase, with liberation of the steroid alcohol. This hydrolysis was shown to follow first-order kinetics, but to be dependent in a remarkable way on the solvent. Ethers are the most effective solvents, followed by others of low polarity including benzene, esters and ketones, while water and alcohols have a strong retarding effect on hydrolysis. Neither acids nor bases produce significant catalysis, and the presence of did not result in incorporation of isotopic... 

The voltammetric behavior of disubstituted alkyl pyridine and benzene esters 121 and several of their dithioic 5,5 -diesters 122 analogs have recently been reported... 

The mobile phase competes with the sample components for adsorption sites on the stationary phase and thereby decreases the number of adsorption sites which are available for the solutes (i.e. sample components). Consequently, use of increasingly polar mobile phases decreases the retention times of solutes. Several solvents used in LSC in order of increasing polarity are Fluoroalkanes, petroleum ether, carbon tetrachloride, cyclohexane, toluene, benzene, esters, chloroform, ethyl ether, dichloroethane, methyl ethyl ketone, acetonitrile, alcohols, water, pyridine, organic acids. 

Apart from exceptional heat resistance, this compound has high resistance to aliphatic and aromatic hydrocarbons, including carbon tetrachloride and benzene, esters of aromatic acids, and higher ethers (aromatic and aliphatic), and also to phosphoric acid. It is not suitable, however, for low molecular weight aliphatic esters, ketones, and amines including anhydrous... 

Figure 7.11 Adsorption of the basic PMMA on the acid silica (Si02) surface from solutions of various solvents of varying acidic and basic characters. The figure illustrates the importance of the Lewis acid-base concept on polymer adsorption. LB solvents (e.g. benzene, esters, ethers, ketones, etc.) can adsorb on the surface instead of PMMA. In contrast, acid solvents can adsorb on PMMA, prohibiting its adsorption on the surface. Thus, adsorption is often maximum when it occurs from inert solvents. Reprinted from Jonsson et al. (2001), with permission from John Wiley Sons, Ltd...

C2H4N2O3, NH2CONHCOOH. Unknown in the free state as it breaks down immediately to urea and COi- The NH4, Ba, Ca, K and Na salts are known and are prepared by treating ethyl allophanate with the appropriate hydroxide. The esters with alcohols and phenols are crystalline solids, sparingly soluble in water and alcohol. They are formed by passing cyanic acid into alcohols or a solution of an alcohol or phenol in benzene. The amide of allophanic acid is biuret. Alcohols are sometimes isolated and identified by means of their allophanates. 

To about ro ml. of the ester add about 0 5 g. of 3,5-dim trobenzoic acid and 0 25 ml. of cone. H3SO4. Heat the mixture gently under reflux for 5 minutes. Add very carefully about 10 ml. of water, make alkaline with NaOH and filter at the pump. Recrystallise the solid 3,5-dinitrobenzoate from benzene and take the m.p. (M.ps., pp. 536-530.)... 

Reference has already been made to the choice of solvent for introducing the mixture to the column. Generally speaking, adsorption takes place most readily from non-polar solvents, such as petroleum ether or benzene, and least from highly polar solvents such as alcohols, esters and pyridine. Frequently the solvent for introducing the mixture to the column and the developer are so chosen that the same solvent serves the dual purpose. 

It is interesting to note that under the influence of aluminium alkoxides (in alcohol or, better, in benzene solution) aldehydes produce the ester (Tischenko reaction) ... 

By refluxing a mixture of the acid (1 mol), alcohol (3-4 mols), dry benzene (375 ml.) and concentrated sulphuric acid (58-60 g.). The ester as formed passes into the benzene layer. Upon the addition of water, separating the benzene layer, and distilling the latter (after washing and dr3dng), benzene and alcohol pass over first, followed by the ester, for example ... 

The benzene - alcohol method is useful for the esterification of valuable monobasic acids, but the b.p. of the ester must be at least 50° higher than that of benzene, for example ... 

Furfuryl acetate. Reflux a mixture of 39 2 g. (34-8 ml.) of redistilled furfuryl alcohol, 48 g. of glacial acetic acid, 150 ml. of benzene and 20 g. of Zeo-Karb 225/H in a 500 ml. bolt-head flask, using the apparatus described under iaoPropyl Lactate. After 3 hours, when the rate of collection of water in the water separator is extremely slow, allow to cool, separate the resin by suction filtration, and wash it with three 15 ml. portions of benzene. Remove the benzene, etc., from the combined filtrate and washings under reduced pressure (water pump) and then collect the crude ester at 74-90°/10 mm. a small sohd residue remains in the flask. Redistil the crude ester from a Claisen flask with fractionating side arm pure furfuryl acetate passes over at 79-80°/17 mm. The yield is 14 -5 g. 

Ethyl maleate of almost equal purity may be obtained by refluxing a mixture of 20 g. of pure maleic a.oid, 37 g. (47 ml.) of absolute ethyl alcohol, 05 ml. of sodium-dried benzene and 4 ml. of concentrated sulphuric acid for 12 hours. The ester is isolated as described for Diethyl Adipate (Section 111,100). The yield of diethyl maleate, b.p. 219-220°, is 26 g. 

This preparation illustrates the Reformatsky reaction, which consists in the interaction of a carbonyl compound, an a-halogen ester (e.g., ethyl bromo-acetate) and zinc In the presence of ether or benzene, followed by hydrolysis. 

Cool the flask in ice, acidify with 10 ml. of cold 1 1-hydro-chloric acid and distil under reduced pressure (water pump) until most of the alcohol is removed. Add water to the residue, extract several times with ether, wash the combined ethereal extracts with N ammonia solution until a test portion gives no precipitate upon acidification. Extract the combined alkahne solutions once with a fresh portion of ether, and add the aqueous solution to an excess of dilute hydrochloric acid the final mixture should still be acidic to Congo red. Collect the crystalhne half-ester by filtration at the pump, wash it with water and dry at 100°. The yield is 14-5 g., m.p. 122-125°. Recrystallise by dissolving in about 40 ml. of warm benzene and adding an equal volume of petroleum ether (b.p. 40- 60°) 13 -5 g. of the colourless half-ester, m.p. 125-126°, are obtained. 

Ethyl phenylethylmalonate. In a dry 500 ml. round-bottomed flask, fitted with a reflux condenser and guard tube, prepare a solution of sodium ethoxide from 7 0 g. of clean sodium and 150 ml. of super dry ethyl alcohol in the usual manner add 1 5 ml. of pure ethyl acetate (dried over anhydrous calcium sulphate) to the solution at 60° and maintain this temperature for 30 minutes. Meanwhile equip a 1 litre threenecked flask with a dropping funnel, a mercury-sealed mechanical stirrer and a double surface reflux condenser the apparatus must be perfectly dry and guard tubes should be inserted in the funnel and condenser respectively. Place a mixture of 74 g. of ethyl phenylmalonate and 60 g. of ethyl iodide in the flask. Heat the apparatus in a bath at 80° and add the sodium ethoxide solution, with stirring, at such a rate that a drop of the reaction mixture when mixed with a drop of phenolphthalein indieator is never more than faintly pink. The addition occupies 2-2 -5 hoius continue the stirring for a fiuther 1 hour at 80°. Allow the flask to cool, equip it for distillation under reduced pressure (water pump) and distil off the alcohol. Add 100 ml. of water to the residue in the flask and extract the ester with three 100 ml. portions of benzene. Dry the combined extracts with anhydrous magnesium sulphate, distil off the benzene at atmospheric pressure and the residue under diminished pressure. C ollect the ethyl phenylethylmalonate at 159-160°/8 mm. The yield is 72 g. 

The formation of acyloins (a-hydroxyketones of the general formula RCH(OH)COR, where R is an aliphatic residue) proceeds best by reaction between finely-divided sodium (2 atoms) and esters of aliphatic acids (1 mol) in anhydrous ether or in anhydrous benzene with exclusion of oxygen salts of enediols are produced, which are converted by hydrolysis into acyloins. The yield of acetoin from ethyl acetate is low (ca. 23 per cent, in ether) owing to the accompanying acetoacetic ester condensation the latter reaction is favoured when the ester is used as the solvent. Ethyl propionate and ethyl ji-butyrate give yields of 52 per cent, of propionoin and 72 per cent, of butyroin respectively in ether. 

Kinetic studies of nitration using dilute solutions of dinitrogen pentoxide in organic solvents, chiefly carbon tetrachloride, have provided evidence for the operation, under certain circumstances of the molecular species as the electrophile. The reactions of benzene and toluene were inconveniently fast, and therefore a series of halogenobenzenes and aromatic esters was examined. 

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