Alkalis strong

The head element nitrogen does not react. White phosphorus, however, reacts when warmed with a concentrated solution of a strong alkali to form phosphine, a reaction which can be regarded as a disproportionation reaction of phosphorus ... 

Phosphine can be prepared by the reaction of a strong alkali with white phosphorus potassium, sodium and barium hydroxides may be used ... 

Oxygen does not read with alkalis. Sulphur dissolves slowly in strong alkalis to give a mixture of sulphite [sulphate(IV)] and sulphide initially ... 

Addition of alkali gives a green gelatinous precipitate of chromium(III) hydroxide, soluble in a large excess of strong alkali. 

The azlactones may be hydrolysed by strong alkali to a-keto acids, for example ... 

There is also the possibility of removing the 2-oxo group by ring cleavage and subsequent recyclization. Lumazine can be hydrolyzed by strong alkali to 2-aminopyrazine-3-carboxylic acid (153) which is converted first into the amide (154) and then cyclized by ethyl orthoformate into pteridine-4-one (155 equation 47) (51JCS474). 

It should be noted that the highest possible absorption rates will occur under conditions in which the hquid-phase resistance is negligible and the equilibrium back pressure of the gas over the solvent is zero. Such situations would exist, for instance, for NH3 absorption into an acid solution, for SO9 absorption into an alkali solution, for vaporization of water into air, and for H9S absorption from a dilute-gas stream into a strong alkali solution, provided there is a large excess of reagent in solution to consume all the dissolved gas. This is known as the gas-phase mass-transfer limited condition, wrien both the hquid-phase resistance and the back pressure of the gas equal zero. Even when the reaction is sufficiently reversible to allow a small back pres-... 

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. 

Strong alkali or heating with dilute acids may lead to hydrolysis of the nitrile, and should be avoided. 

These can be purified by extracting acidic and basic impurities with aqueous base or acid, respectively. However, they are somewhat sensitive to strong alkali which slowly cleaves the disulfide bond. TTie lower-melting members can be fractionally distilled under vacuum. The high members can be recrystallised from alcohol, toluene or glacial acetic acid. 

Ignoring alkaline service. Just because strong alkalies do not cause severe overall corrosion in carbon steel or stainless steel, don t overlook stress coito-sion, cracking, or effects on other materials. 

The principal applications of these plastics arose from their very good chemical resistance, as they are resistant to mineral acids, strong alkalis and most common solvents. They were, however, not recommended for use in conjunction with oxidising acids such as fuming nitric acid, fuming sulphuric acid or chlorosulphonic acid, with fluorine or with some chlorinated solvents, particularly at elevated temperatures. 

Both acids and alkalis will adversely affect the material. Strong alkalis and acids will cause decomposition. The water absorption is high and consequently casein is easily stained. As a corollary to this it may be dyed without difficulty. Acidic and basic water-soluble dyes are normally used. Typical properties of casein plastics are given in Table 30.2. 

Hot oleum (>50°C), strong alkalis, fluoride solutions, sulphur trioxide Strong alkalis, especially >54°C, distilled water >82°C, hydrofluoric acid, acid fluorides, hot concentrated phosphoric acid, lithium compounds >1 77°C, severe shock or impact applications Strong oxidizers, very strong solvents... 

Decomposition of trichloroethylene can occur upon contact with naked flames, red-hot surfaces, hot elements of electric heaters, or intense UV light with the generation of acidic and highly-toxic products. The presence of reactive contaminants, e.g. acids, strong alkalis, highly-reactive metals, may also result in decomposition to similar products. 

In addition to the health hazards mentioned above, it is important be aware of the potential for explosions due to the Cannizzarro reaction ([77], pp. 36-37). When strong alkali is mixed with formaldehyde solutions, the Cannizzarro reaction will result in a rapid and spontaneous reaction even at relatively low temperatures. Depending on conditions, an induction period may be seen. The main organic products of this reaction are methanol and formic acid (salt form). In addition, significant amounts of hydrogen are evolved. The potential for explosions in closed containers is high, and even open containers will often erupt. 

The PVF is made by acidic reaction between poly(vinyl alcohol) (PVA) and formaldehyde. The poly(vinyl alcohol) is, in turn, made by hydrolysis of poly(vinyl acetate) or transesterification of poly(vinyl acetate). Thus, residual alcohol and ester functionality is usually present. Cure reportedly occurs through reaction of phenolic polymer hydroxyls with the residual hydroxyls of the PVA [199]. The ester residues are observed to reduce bond strength in PVF-based systems [199]. This does not necessarily extend to PVF-P adhesives. PVF is stable in strong alkali, so participation of the acetals in curing is probably unimportant in most situations involving resoles. PVF is physically compatible with many phenolic resins. 

Furnace mortars are used over a very wide range of conditions. They are resistant to nonoxidizing acids, alkalis, and solvents up to 190°C. Carbon fillers should be used for conditions involving strong alkalis and compounds containing fluorine. 

The plienolic/asbestos laminates (used up to 200°C) have excellent resistance to most mineral and organic acids but are attacked by strong oxidizing agents such as nitric and concentrated sulfuric acids and strong alkalis such as sodium and potassium hydroxide. Tanks, scrubbers, columns, pumps, pipes, etc., are fabricated from plienolic/asbestos laminates. 

Epoxy resin paints, inferior to chlorinated rubber for resistance to strong acids, are excellent for dilute acids and strong alkalis. They produce a harder, more abrasion-resistant coating than does chlorinated rubber and are much better for resistance to fats, oils and many organic solvents. Table 3.50 gives data on the chemical resistance of epoxy resin coatings to different materials. 

By the action of strong alkalis the carbinol form (VIII) is converted into dihydroberberine (IX) and oxyberberine (X). 

Hydrolysis of the intermediate epoxy acetate is generally carried out with strong alkali if base-sensitive groups are present, milder conditions (e.g., potassium bicarbonate, potassium carbonate) can be employed. If commercial peracetic acid (which contains sulfuric acid) is used for epoxidation, the intermediate epoxy acetate cannot be isolated, but is hydrolyzed in situ by the acid to the desired ketol. Acid hydrolysis will also retain 3-acetates, if present. ... 

The synthetic capabilities of this compound arc not yet exhausted. Acetoacetic ester and its alk d derivatives undergo decomposition in two wajs, accoidiiig to whether dilute alkalis and acids or, on the other hand, strong alkalis are employed. 

The kinetics of alkaline hydrolysis of an ester can be followed by the pH-stat method, in which the pH is held constant by adding a solution of strong alkali to the reacting ester solution. The volume of alkali added in order to keep the pH constant is recorded as a function-time. Find the volume function needed to determine the rate constant that is, given the volume-time data for this type of experiment, what plot or calculation will yield the rate constant ... 

Clilorine dissolves rapidly in strong alkali solutions to produce hypo-elilorite solutions. Under eertain eonditions these solutions are prone to deeompose with e.xplosive foree. 

When a jo /r-A-alkylcarbolinium salt, unsubstituted at the ind-N atom, is treated with strong alkali, a yellow to deep orange, strongly basic solid separates. Although such products almost invariably give poor microanalytical values they can be shown to be derived from the quaternary hydroxide by loss of a molecule of water—hence the name anhydro-bases or anhydronium bases.All four carbolines form anhydro-bases e.g., j9 /r-A-methyl-j8-carbolinium iodide (419) gives 420. Most of the evidence bearing on the structures of these bases has been summarized, and discussion will therefore be limited to a few of the recent aspects of the chemistry of these compounds. 

Greater para than ortho deactivation is seen in the hydrolysis (HCl in AcOH, 100°, 1 hr) of the nitro group in 5,6-diphenyl-2-nitro-3-pyrazinone (218) but not in 6-phenyl- or 3,6-diphenyl-2-nitro-5-pyrazinone (219). Similarly, acid hydrolysis of a 2-bfomo substituent in 3-pyrazinone, but not in 5-pyrazinone, is readily accomplished. All flve of these pyrazinones are stable in strong alkali or alkoxide as a result of complete anionization. Decreased reactivity of... 

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