Dilute alcoholic solutions

The first improvement of the Bucherer-Bergs reaction was the Bucherer-Lieb variation using the diluted alcoholic solution as described at the end of section 7.2.2. The Bucherer-Lieb variation is possibly the most popular process for synthesizing hydantoins. Another notable variation is the Henze modification using fusing acetamide as the solvent in place of water, benzene or 50% alcohol. Recently, ultrasound-promoted hydantoin synthesis has been reported to accelerate the reaction. 

A mixture of 60 g (0.408 mol) of isatin, 200 mL of 34% potassium hydroxide in diluted alcohol solution, 88 g (1.22 mol) of ethyl methyl ketone and 375 mL of water were stirred and heated under reflux for 72 hours. About 125 mL of liquid was removed by distillation the residue was made slightly acidic and filtered. The filtrate was made strongly acidic to precipitate the reaction product, which was collected by filtration, washed, dried, weighed 70 g (85% yield). 

Benzyl chloride reacts with thiourea in dilute alcoholic solution to give S-benzyl-i5o-thiuronium chloride ... 

Pardon us if you have not taken a course in separation processes yet, but you do not need to know what a distillation column is to read the example. In a simple-minded way, we can think of making moonshine. We have to boil a dilute alcohol solution at the bottom and we need a condenser at the top to catch the distillate. This is how we have the V and L manipulated variables. Furthermore, the transfer functions are what we obtain from doing an experiment, not from any theoretical derivation. 

TetrahydroxyhexeneS. The hexynetetrol obtained above was reduced to the corresponding hexenetetrol by hydrogenation over Bourguel s catalyst. In a typical experiment the hexynetetrol, alone, or in aqueous or dilute alcoholic solution, was placed in a filter flask of at least three times the volume of the solution to be reduced, together with perhaps 1 ml. of Bourguel s... 

The S S menbranes were immersed in dilute alcohol solutions during shipment and storage. The alcohol could be replaced by water, but the menbrane could not be allowed to -dry or it would shrink in an irreversible manner to become a useless membrane. Recalling the unsuccessful tests of Section II we heated the S S membranes under water to temperatures in the order of 80 -... 

A plant for the fermentation of sulfite waste liquor in America was built at Mechanicsville, New York, by the West Virginia Pulp and Paper Company in 1914. The alcohol stills and some of the other equipment were imported from Germany and were considered the most modern at that time. In comparison to present American stills, these were very inefficient because they were wasteful of steam and did not recover all the alcohol. This plant reused the yeast from a previous fermentation for succeeding fermentations. The plant produced about 221,000 gallons of alcohol per year in 1919. In later years, because of the inefficiency of the alcohol stills with dilute alcohol solutions, molasses was added to the sulfite waste liquor to increase the alcohol content. The plant operated until 1939, when it was closed because of obsolescence. 

According to Claude Bernard the action of anesthetics is very general. They react not only with animals but also with plants. Bose has found that plants anesthetized with ether go through a preliminary period of increased irritability or stimulation. A dilute alcohol solution acted as a stimulant, whereas a concentrated alcohol solution acted as a depressant. Nichols applied chloroform to the wall of an intemode of Nitella by means of a capillary pipette. An area of non-motile protoplasm was produced at the point of application of the anesthetic. This area of non-motile protoplasm resumed its movements later, so the process appears to be a reversible one. Nichols considers the effect to be due to gelation, thus providing us with a case of reversible coagulation in plants accompanied by anesthesia of the part affected. 

Olano, A. 1978. Treatment of forms of lactose with dilute alcoholic solution of sodium hydroxide. J. Dairy Sci. 61, 1622-1623. 

A few drops of a very dilute alcoholic solution may be used as an internal indicator. 

Addition of extraneous tanning materials (see chapter on Tanning Substances) is indicated by the fact that a very dilute alcoholic solution, obtained in the cold and filtered, is coloured more or less intense black rather than green by ferric chloride. 

In the first study of hydrolysis of Fe(OEt)3 carried out by Thiessen et al. [1577], the precipitate of cubic crystals Fe203 4H20 was obtained after refluxing of diluted alcoholic solution of iron ethoxide for a few hours. Hydrolysis of iron ethoxide by excess of water results in amorphous precipitate, which on thermal treatment at first gives y-Fe203 and then a-Fe203 (in contrast to the precipitates of (X-FeOOH, which precipitate from aqueous solutions) [1776]. 

The most unstable form of the amorphous variety is colloidal silver, prepared by reduction of an ammoniacal or dilute alcoholic solution of silver nitrate with sodium citrate, sodium potassium tartrate, dextrin, tannin, or formaldehyde, with subsequent addition of ferrous sulphate.13 If forms a chocolate, pale-lilac, blue, or green mass, and dissolves in water to a deep-red solution. The colour depends partly on the mode of... 

The presence of 2-methy-3-furanthiol (II), an odoriferous compound evocative of cooked meat, has been reported in red Bordeaux (Bouchilloux et al. 1998b Kotseridis et al. 2000) and de Rioja wines (Aznar et al. 2001). Concentrations of this compound in wine vary from 25 to 140ng/L, with the highest values in Champagnes. As the perception threshold of 2-methyl-3-furanethiol in model dilute alcohol solution is 4 ng/L, this thiol certainly contributes to the toasty aroma in wines. 

More recently, Le Berre et al. (2007) observed reduced volatility of whisky lactone in hydroalcoholic solution compared to that in water, but not for isoamyl acetate. The same authors found a synergic effect of the woody note on the fruity odour in the aqueous solution, which disappeared with the addition of ethanol. They also observed that the woody note (for the highest woody odour concentrations) was masked by the fruity odour, in both aqueous and dilute alcohol solutions. 

Benzylarsinic acid, CgHs.CHa.AsO(OH)2.2— When benzyl iodide, arsenious oxide, and potassium hydroxide react in dilute alcohol solution, the following changes take place ... 

Platinum bis-S-chlorovinylbis-jSjS jS"- trichlorotrivinylarsine, [(CHCl=CH)3As]jPt(CH=CHCl)si.—This product results from the interaction of a dilute alcoholic solution of chloroplatinic acid and an alcoholic solution of the tertiary arsine. It crystallises from alcohol in very pale yellow needles, and from benzene in pale yellow plates, M.pt. 198° C. with decomposition. 

Acetoxymercuri-2 4-dichloroaniline 1 is prepared in the usual manner from 2 4-dichloroaniline and mercuric acetate in dilute alcoholic solution. It melts at 170° to 171° C., forms a hydroxide and chloride, M.pt. 280° C. and 198° C, respectively. The acetyl derivative, M.pt. 288° yields 2 4 6-trichloroacetanilide. In this case a mer-curi-bis compound is obtained by the action of sodium hydrogen sulphate on the acetate. It is Q-mercuri-his- 4<-dichloroaniUne, M.pt. 1GS° C. 

This product is a yellow powder, formed by prolonged boiling of a dilute alcoholic solution of mercuric acetate with sodium p-nitrophenoxide. It yields a double salt with pyridine, which is a scarlet powder decomposing at 190° C. into its constituents. The mercury must be ortho to the hydroxyl group, since 2 6-dibromo-p-nitrophenol does not yield a corresponding derivative. The anhydride does not react with potassium iodide or hydrogen sulphide, but with iodine it gives mercuric iodide and o-iodo-p-nitrophenol. 

It is clear from these tables that the figures have no theoretical significance, because actually thymolphthalein and phenolphthal-ein are much more sensitive to hydroxyl ions than is indicated above. The true sensitivity can be determined only by using buffer solutions. It should be remembered, furthermore, that alcohol not only changes the color intensity but the color as well. Phenolphthalein in aqueous alkaline solution is cherry red, assumes a violet tint in dilute alcoholic solution, and is bluish violet in concentrated alcohol. Furthermore the color intensity of an alkaline phenolphthalein solution is much less in alcohol than in water. ... 

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