Mild alkalis

Other sources of hazard arise from the handling of such chemicals as concentrated acids, alkalis, metallic sodium and bromine, and in working with such extremely poisonous substances as sodium and potassium cyanides. The special precautions to be observed will be indicated, where necessary, in the experiments in which the substances are employed, and will also be supplied by the demonstrator. The exercise of obvious precautions and cautious handling will in most cases reduce the danger to almost negligible proportions. Thus, if concentrated sulphuric acid should be accidentally spilled, it should be immediately washed with a liberal quantity of water or of a solution of a mild alkali. 

Polypropylene has a chemical resistance about the same as that of polyethylene, but it can be used at 120°C (250°F). Polycarbonate is a relatively high-temperature plastic. It can be used up to 150°C (300°F). Resistance to mineral acids is good. Strong alkalies slowly decompose it, but mild alkalies do not. It is partially soluble in aromatic solvents and soluble in chlorinated hydrocarbons. Polyphenylene oxide has good resistance to ahphatic solvents, acids, and bases but poor resistance to esters, ketones, and aromatic or chlorinated solvents. 

The 20-acetylamino-17a,20-epoxide formed by reaction with peracid is also relatively stable to mild alkali, again permitting hydrolysis of a 3y5-acetoxy function. 

If the compound itself is desired, the salt is dissolved in water and the solution saturated with a mild alkali such as potassium carbonate. The product is then extracted with chloroform, dried, and after removal of the chloroform, distilled. 

NITRILE OXIDES. Nitrile oxides are a well known class of compds represented by R.C N- 0, and are usually prepd by treating hydroxamic acid chlorides with a mild alkali, thus eliminating HQ (Ref 2). Wieland (Refs 1 3) was responsible for the first isolation of free nitrile oxides. These compds are somewhat unstable, showing a marked tendency to dimerize to (he corresponding furoxanes (1,3-dipolar addition) (Refs 2 3). The nitrile oxides add to a considerable number of carbenes, as benzonitrUe oxide (for example) to a large number of olefins in ether at 20° (Ref 3)... 

To prepare the mild-alkali-extract, dry watermelon cell walls were suspended in a solution of 0.1 N NaOH, and allowed to react with stirring at room temperature for 15 minutes. A pH of 13, as indicated by pH paper, was kept constant during this period by addition of 0.1 N NaOH. To ensure complete reaction, the treatment was continued overnight at 4 °C. The soluble portion was separated by centrifugation at 10,000 RPM for 20 minutes in a Sorval GSA rotor. The insoluble portion was washed twice with water. The supernatants were combined and, after neutralization to pH 7.0 with acetic acid, dialyzed against distilled water and freeze dried. 

Xyl residues were removed from mild-alkali-extract and EPG-digestion-resistant fragments by treatment with anhydrous HF at -12 C using the procedure described by Mort et al. [7]. 

The mild-alkali-extract was digested to completion with excess EPG at room temperature for at least 48 hours. Figure 1 shows the separation of the products on a Dionex PAl ion-exchange column. The limit digest of pectic acid (nonesterified HG) by this enzyme is mono-. 

Mole percent of sugars in watermelon cell walls and in the mild-alkali-extract of watermelon cell walls... 

When scouring synthetic fibres that are to be dyed with disperse dyes, nonionic scouring agents are best avoided unless they are formulated to have a high cloud point and are known not to adversely affect the dispersion properties of the dyes. Conversely, when scouring acrylic fibres, anionic surfactants should be avoided [156] because they are liable to interfere with the subsequent application of basic dyes. These fibres are usually scoured with an ethoxylated alcohol, either alone or with a mild alkali such as sodium carbonate or a phosphate. 

Endo H, peptide N-glycanase F and mild alkali treatment... 

Epimerization of etoposide The anticancer agent etoposide contains a five-membered lactone function that is significantly strained because it is trans-fused. This material is readily converted into a relatively strain-free cw-fused system by treating with very mild alkali, e.g. traces of detergent, and produces an epimer (see Section 3.4.4) called picroetoposide. This isomer has no significant biological activity. 

Cleavage of ficine (4) to yield the parent flavonoid has been achieved, using pyrolysis or mild alkali in methanol (5). Vochysine (7) has been cleaved in the presence of alcohol to give the parent flavan (7). The nitrogenous part of the molecule cannot be detected after cleavage as it breaks down under alkaline conditions. 

Slaked Quicklime + mild alkali = limestone + caustic alkali. 

From these he concluded that mild alkali = caustic alkali + fixed air. 

The chemists or alchemists gradually acquired a knowledge of the various salts produced by the action of acids on nitrum and of the transformations of the various salts from one form to another, by the action of acids on the different salts—e.g. sulphuric acid on sodium chloride. The carbonates of the alkalies were called mild alkalies to distinguish them from the caustic alkalies. It was known quite early that the caustic alkalies are obtained by the action of quicklime on the mild alkalies for example, the Latin Geber 7 and Albertus Magnus of the thirteenth century knew that the ash of plants furnished a caustic alkali when treated with quicklime and water. The process is essentially that employed to-day. 

In an important paper entitled Experiments upon magnesia alba) quicklime, and other alcaline substances, published in 1755,1 J. Black first made clear the relations between caustic alkali and mild alkali that is, between the alkali hydroxides and alkali carbonates. These relations were not understood by the early chemists. They believed the mild alkalies and alkaline earths—that is, the carbonates of the alkalies and alkaline earths—to be elementary substances that the causticity of lime was due to the union of fire-matter or phlogiston with elemental chalk and the conversion of mild alkali into caustic alkali, with the simultaneous regeneration of chalk, by boiling the former with caustic lime, was due simply to the transfer of the phlogiston or fire-matter from the lime to the mild alkali. Otherwise expressed Quicklime=Chalk-f Fire-matter. J. Black proved this hypothesis to be untenable. H. L. Duhamel du Monceau 2 had shown nine years earlier in a memoir Diverses experiences sur la chaux, that limestone loses weight when calcined and regains it little by little on exposure to air. 

It is well to remember that at the time Black undertook his investigations, the prevalent belief was that the alkaline carbonates, or mild alkalies, were simple bodies, that when they were combined with phlogiston, they yielded the caustic alkalies. So when limestone was heated and yielded... 

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