Insoluble residues

When the ij hours boiling is complete, preheat a Buchner funnel and flask by pouring some boiling water through the funnel with the filter-paper already in position, and then quickly filter the boiling solution. Transfer the filtrate to a beaker to cool, and then wash the insoluble residue of diphenylurea on the filter twice with hot water, and drain thoroughly. Cool the filtrate in ice-water the monophenylurea separates as colourless needles. Filter at the pump and drain well. Recrystallise the crude product from boiling water, as in the previous preparation. Yield of monophenylurea, 2 5-3 g. m.p. 147°. 

The insoluble residue of diphenylurea from the original filtration is chemically almost pure. It may be recrystallised from hot rectified spirit or ethanol, a process which will be necessary if the material contains fragments of porcelain. When using either of these solvents, however, the hot solution should be filtered at the pump using a small Buchner funnel and flask which again have been preheated by the filtration of some of the hot solvent, as the solution when cooled rapidly deposits the diphenylurea. iSym-Diphenylurea (or carbanilide) is thus obtained as fine colourless crystals, m.p. 237° yield, 1-1 5 S ... 

The pH of a freshly prepared 0.4% solution of stannous fluoride is between 2.8 and 3.5. Initially clear aqueous solutions become cloudy on standing owing to hydrolysis and oxidation. The insoluble residue is a mixture containing stannous and stannic species, fluoride, oxide, oxyfluorides, and hydrates. 

Psyllium Seed Gum. PsyUium seed gum [8036-16-9] is derived from plants of the genus Plantago several species of which are used as commercial sources. However, most current production is from Plantago ovata grown in India. The gum is located in the coat which is removed by cracking. The gum is then extracted with boiling water and separated from the insoluble residue by filtration. It consists of mixtures of both neutral and acidic polysaccharides, the composition of which is species dependent (66). 

The reaction of finely ground ores and an excess of carbon at high temperatures produces a mixture of metal carbides. The reaction of pyrochlore and carbon starts at 950°C and proceeds vigorously. After being heated to 1800—2000°C, the cooled friable mixture is acid-leached leaving an insoluble residue of carbides of niobium, tantalum, and titanium. These may be dissolved in HF or may be chlorinated or burned to oxides for further processing. 

In addition to the normal problems of completely dissolving particles of water-thickening polymers, xanthan gum contains insoluble residues which decrease polymer injectivity. Various methods of reducing insolubles content and improving xanthan solution injectivity are available (80—87). None appears economically viable. Oxygen scavengers (88) and bactericides (77,89) are commonly used to stabili2e injected polyacrylamide and xanthan gum solutions (90—102). 

The green Hquor, ie, the solution obtained on dissolving the smelt, contains an insoluble residue called dregs, which give a dark green appearance. 

Apart from added stabilizers, commercial grades of trichloroethylene should not contain mote than the following amounts of impurities water 100 ppm acidity, ie, HCl, 5 ppm insoluble residue, 10 ppm. Free chlorine should not be detectable. Test methods have been estabUshed by ASTM to determine the following characteristics of trichloroethylene acid acceptance, acidity or alkalinity, color, corrosivity on metals, nonvolatile-matter content. 

Acid Detergent Fiber. The ground sample is heated for 1 h under reflux in a solution of 2% cetyltrimethyl ammonium bromide [57-09-0] in IN sulfuric acid [7664-93-9]. The acid hydrolyzes and dissolves the nonceUulosic polysaccharides. The insoluble residue, relatively free of hemiceUuloses and containing aU the ceUulose and lignin, is filtered, dried, and corrected for ash to give the ADF value. 

CeUulose may be extracted from the ADF with 72% sulfuric acid (w/w) at 4°C for 24 h leaving an insoluble residue of lignin. The loss in mass of the ADF estimates the ceUulose component. Alternatively, ceUulose may be estimated by hydrolysis of the ADF and determination of glucose. 

Noscapine [128-62-1] (45) is the second most abundant alkaloid found in opium. Unlike most opium alkaloids, however, it has an isoquinoline rather than a phenanthrene ting system. Noscapine was first isolated in 1817 but its antitussive activity was not demonstrated pharmacologically until 1952 (63). Clinical studies have confirmed its effectiveness. It is not a narcotic and has a wide margin of safety when given orally. Death could be produced in rats only with doses > 800 mg/kg (64). Noscapine is isolated from the water-insoluble residue remaining after processing opium for the manufacture of morphine. 

The purple color end point is not sharp, but as soon as the red hue of the mixture has distinctly changed toward purple, this point is considered reached. A variation of 5-10 cc. either way has little effect, but a large excess gives a large alkali-insoluble residue. 

After the addition of the last of the /)-nitroaniline, the stream of phosgene is continued for five minutes and then shut off. The flame under the flask is then turned up and the ethyl acetate distilled. Care must be taken at the end not to overheat the residue. The brown residue (Note 5) is treated with 800 cc. of hot dry carbon tetrachloride, and the insoluble residue (the di-substituted urea) is removed by filtration. 

PhPO(OH)2]. Dissolved in a minimum amount of methanol, filtering off an insoluble residue of inorganic phosphate, then ppted by adding an equal volume of diethyl ether. Washed with diethyl ether and dried [Tsuboi Biochim Biophys Acta 8 173 7952]. 

Phosphorus pentabromide [7789-69-7] M 430.6, m <100 , b 106 (dec). Dissolved in pure nitrobenzene at 60°, filtering off any insoluble residue on to sintered glass, then crystallised by cooling. Washed with dry Et20 and removed the ether in a current of dry N2. (All manipulations should be performed in a dry-box.) [Harris and Payne J Chem Soc 3732 1958]. Fumes in moist air because of hydrolysis. HARMFUL VAPOURS. 

Cmchonine, C19H22ON2. This alkaloid is usually present in cinchona and cuprea barks. One of the best sources is Cinchona micrantha bark. It occurs in the crude quinine sulphate mother liquors. The mixed alkaloids recovered from these may be extracted with ether to remove quinidine and cinchonidine and the insoluble residue boiled with successive small quantities of alcohol, from which cinchonine crystallises on cooling. The crude alkaloid is neutralised with dilute sulphuric acid and the sulphate recrystallised from boiling water. Cinchonine so prepared contains quinidine, from which it may be freed by crystallisation from boiling alcohol until it ceases to exhibit fluorescence in dilute sulphuric acid. It will then still contain 10 to 15 per cent, of dihydrocinchonine, which may be removed by reprecipitation as the cuprichloride, B. 2HC1. CuClj, or by the simpler mercuric acetate process of Thron and Dirscherl. ... 

Column is clogged due to the presence of protein aggregates and/or insoluble residuals from biological samples... 

The metals react with most non-metals especially if heated, but resist alkali attack and are less reactive towards acids than might be expected. Concentrated HCl probably reacts most rapidly, but even here insoluble residues remain in the cases of Th (black). Pa (white) and U (black). Those of Th and U have the approximate compositions HThO(OH) and UH(OH)2. Concentrated HNO3 passivates Th, U and Pu, but the addition of F ions avoids this and provides the best general method for dissolving these metals. 

A mixture of a-naphthol 41 (15.0 g, 0.1 mol), phenylhydrazine 42 (11.0 g, 0.1 mol) and sodium bisulfite solution (36 %, 250 g) was heated at reflux for 15 h. A further 4 g of phenylhydrazine was added and heating continued for 15 h, after which time the majority of the a-naphthol was consumed. After cooling, the mixture was extracted with ether. The oily, ether and aqueous insoluble residue was warmed with cone. HCl until a dark crystalline mass developed. After cooling, the mixture was extracted with ether. The organic extract was dried and concentrated to afford a crystalline residue which was purified by recrystallisation from ethanol to afford the product 43 as a white crystalline solid, mp 225 °C. A reaction yield is not given. 

The alkali-insoluble residue comprising ethyl p-cyclohexyloxybenzoate is hydrolyzed by refluxing with 10% sodium hydroxide solution for about 3 hours. The alkaline reaction mixture is acidified with hydrochloric acid whereupon p-cyclohexyloxybenzoic acid precipitates. The precipitate is separated by filtration, washed with water and dried. It melts at about 178° to 180°C. Yield about 7%. 

According to U.S. Patent 3,225,030, 1,500 grams of dried ground plant of Vinca rosea were Intimately mixed with 1,000 ml of a 2% tartaric acid solution, and the mixture was extracted with three 9-liter portions of benzene. The benzene extracts were combined and were concentrated in vacuo to about 1,500 ml. The concentrate was mixed with 1 liter of 2% tartaric acid and the mixture was steam-distilled under reduced pressure until all of the benzene had distilled over. The insoluble residue was dissolved in hot methanol, a second 1-liter portion of 2% tartaric acid solution was added, and the mixture was steam-distilled under reduced pressure until all of the methanol had distilled. 

Filtration Separation of solution from insoluble residue ... 

A stirred mixture of methyl 1 //-azepine-l-carboxylate (24, R = Me 0.75 g, 5 mmol) and nonacar-bonyliron(O) (1.82 g, 5 mmol) in hexane (30 mL) under N, was healed under reflux for 20 min. The solution was cooled and then filtered through Celite to remove a small quantity of dark, insoluble residue. The filtrate was evaporated to yield the crude product, which was recrystallized (hexane) yield 1 g (69%) mp 116-116.5 C. 

A7M aqueous solution of LiOII-H20 is added to a 0.35 M solution of the sultam 11 in THF and vigorously stirred at 65 "C for 3 — 5d. Evaporation in vacuo, trituration of the residue with CH2CI2 and evaporation of the dried extracts gave sultam R NH. Acidification of the CH2C12 insoluble residue with 2N aq HC1, saturation with NaCl, extraction with CU2C12 and evaporation of the dried (MgS04) extracts gave the crude carboxylic acid 12 which is purified by distillation. 

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