Alkaline hydroxide

Most mineral acids react vigorously with thorium metal. Aqueous HCl attacks thorium metal, but dissolution is not complete. From 12 to 25% of the metal typically remains undissolved. A small amount of fluoride or fluorosiUcate is often used to assist in complete dissolution. Nitric acid passivates the surface of thorium metal, but small amounts of fluoride or fluorosiUcate assists in complete dissolution. Dilute HF, HNO, or H2SO4, or concentrated HCIO4 and H PO, slowly dissolve thorium metal, accompanied by constant hydrogen gas evolution. Thorium metal does not dissolve in alkaline hydroxide solutions. 

Ferrous hydroxide in the presence of alkaline hydroxides or carbonates reportedly reduces carbon tetrachloride to methylene chloride (29). 

It was found recently that the cyclization requires the application of 2 moles of alkaline hydroxide in practice, a small excess was used. It was demonstrated that the cyclization is termined wdthin 15 min, and even sooner with a-aryl or 2-A -aIkyl derivatives." ... 

Suggested values of T alkalinity hydroxide alkalinity, and silica vary with the operating pressure, decreasing in inverse proportion to pressure increases above 900 psig (6.21 MPa). 

Perchlorotriphenyl methyl radicals are particularly persistent . Among the factors contributing to the exceptional persistency of this kind of radicals the steric shielding of the a-(tricovalent) carbon is predominant. Only hydrogen or electron can reach the carbon radical. Thus, when perchloro radicals are formed in a DMSO-alkaline hydroxide solution an electron transfer occurs, leading to the perchlorocarbanions. It is assumed that the donor is the DMSO carbanion. 

This oxide catalyses the violent or even explosive decomposition of hydrogen peroxide. This reaction explains the numerous accidents mentioned involving the contact of hydrogen peroxide with rusted iron. Two accidents of this nature dealt with mixtures of hydrogen peroxide with ammonia and an alkaline hydroxide The detonations took place after a period of induction of respectively several hours and four minutes. Iron (III) oxide also catalyses the explosive decomposition of calcium hypochlorite. 

Accidents are often caused by the violent polymerisation of aziridine. To avoid it, this amine needs to be handled or stored in a diluted solution when it is cold, and alkaline hydroxide in the solid state is present. 

Trinitrotoluene leads to explosive mixtures with alkaline hydroxides. If this mixture is made in methanol, it is explosive, even at a temperature of -65°C (see table about trinitrotoluene decomposition temperatures on p.296). 

The hydrolysis of ethyl acetate (B) with an alkaline hydroxide (A] non-aqueous solutions is believed to have the third order rate equation... 

Experiment.-—About 0-1 g. each of benzil and benzoin are dissolved in a test tube in 10 c.c. of alcohol and a few drops of alkaline hydroxide solution are added in the cold. A fine red colour is at once produced and disappears when the liquid is shaken with air. The colour reappears after a short time and can be caused to disappear by renewed shaking these changes may be brought about repeatedly. When, after a fetr more drops of alkali have been added, the colour does not reappear there is no more benzoin left in the solution. Quite pure benzil does not give the colour. 

A. Linares-Solano, D. Lozano-Castello, M.A. Lillo-Rodenas and D. Cazorla-Amoros "Carbon Activation by Alkaline Hydroxides Preparation and Reactions, Porosity and Performance . In Ljubisa R. Radovic, editor. Chemistry and Physics of Carbon CRC Press, Taylor Francis Group, Boca Raton, FL (2008), ISBN 978-1-4200-4298-6. 

In many cell designs, the electrolyte is circulated (mobile electrolyte) so that heat can be removed and water eliminated by evaporation (6). Since KOH has the highest conductance among the alkaline hydroxides, it is the preferred electrolyte. Approximately of the water formed at the anode migrates across the electrolyte and exits in the cathode. 

Cobalt(lI) hydroxide is obtained as a precipitate when an alkaline hydroxide is added to an aqueous solution of cobalt(ll) salt ... 

Mercury(ll) sulfide dissolves in concentrated solutions of alkali or alkaline-earth metal sulfides forming thiosalts, such as Na2[HgS2] XFI2O. Such thio-salts are stable in solution only when alkaline hydroxides are present in excess. These salts also are obtained as bright and deliquescent needles when HgS is heated with sulfur and alkaline hydroxides. 

Hard silvery-white metal hexagonal close-packed crystal structure density 12.41 g/cm3 at 20°C melts at 2,334°C vaporizes at 4,150°C electrical resistivity 7.1 microhm-cm at 0°C hardness (annealed) 200-350 Vickers units Young s modulus 3.0x10 tons/in magnetic susceptibility 0.427 cm /g thermal neutron absorption cross section 2.6 barns insoluble in water, cold or hot acids, and aqua regia can be brought into aqueous phase by fusion of finely divided metal with alkaline hydroxides, peroxides, carbonates and cyanides. 

With the exception of the alkaline hydroxides NaOH, KOH and possibly the fluorides KF, NaF, the direction of the e.m.p. indicates that all monovalent anions are repelled from the free surface of waters less than the cations Li , Na , K ,Cs . Divalent ions show on the other hand only slight differences. As has already been noted the fact that the surface tension of water is raised by the addition of salts indicates that repulsion of the salt as a whole from the surface must take place. 

The following reactions demonstrate that the electrophilic ester carbonyl groups of (16) predominantly determine the reactivity Heating (16b) for several hours in ethanol saturated with HC1 affords (16a) by transes-terfication. Ester hydrolysis and decarboxylation occur at room temperature in the presence of dilute alkaline hydroxide. Hydrolysis of (16a R = R2 = R3 = Me) to 3-carboxy-2-pyrrolone 21 succeeds in the presence of aqueous methanolic KOH at 60°C. Subsequent HC1 work-up at 0°C furnishes 21 with 82% yield (86UP1). (See Fig. 11.)... 

During the reduction, nitrite ions and polysulphides are produced. The hydrolysis reaction (17) is rather slow, if performed in a medium of alkaline hydroxides alone. It can proceed considerably more rapidly if carried out in the presence of HS ions (18). 

Refs 29 31 ).Brisance by Sand Test 54.4 to 60.4 g sand crushed vs 48g for TNT Chemical reactivity comparable with RDX except that HMX is not easily decompd by alkaline hydroxide, and coned H2S04 liberates a little more than 1/3 of HN03 while with RDX a little more than 2/3 is liberated... 

Reaction XXVII. Condensation of Chloroform with Phenols and simultaneous Hydrolysis of the Product (Reimer-Tiemann). (B., 15, 2585.) —This is a well-known method for the preparation of phenolic-aldehydes. The phenol is treated with chloroform and an alkaline hydroxide, when — CHC12 enters the ortho- and to a lesser extent the para-position to the hydroxyl group hydrolysis to an aldehyde then takes place. 

Dioxetanes.1 The epoxides (1) of allylic hydroperoxides are converted into 1,2-dioxetanes (2) on treatment with this base in aqueous ether. Alkaline hydroxides are unsatisfactory. The main limitation is the availability of the allylic hydroperoxides. 

The chemical composition with respect to Si and metallic impurities (mainly Fe, Ca, Al) is generally determined by wet chemical methods in combination with standard spectroscopic techniques (AAS, AES, XRF) (Table 8) [224-226]. A precondition is the dissolution of the powder. Typical dissolving processes are fusion with sodium carbonate or mixtures of sodium carbonate and boric acid, with alkaline hydroxides [225, 226] and special acid treatments [225]. A more effective analysis based on optical emission spectroscopy allows the direct analysis of impurities in the solid state and requires no dissolution step [227]. 

Practically insoluble in water, ethanol, chloroform, and diethyl ether freely soluble in dilute solutions of alkaline hydroxides and carbonates soluble in dilute hydrochloric acid.1... 

For the purification of this biopolymer no treatment with bases (e.g., sodium or potassium hydroxide) should be carried out. Traces of alkaline hydroxides can accumulate inside the polymer and can induce irritation of the skin. Other possibilities for successful washing and cleaning of BC are described in a patent. The authors have used solutions with an alkaline reaction - but free of bases - and list medical application [158]. 

This trend observed for chemically activated carbon fibers is very different from that obtained for the ACF prepared by physical activation of the same raw carbon fiber with C02 and steam, where the maximum scattering appears at the external zone of the fiber (see Figure 4.19). In the case of NaOH and KOH activation, the results indicate that the activating agents penetrate the fiber, which is a new interesting observation, which points out that alkaline hydroxides penetrate much better than C02 and steam. The different evolution of porosity obtained for the chemically activated carbon fibers compared to the physically activated carbon fibers could be explained considering the important differences between the mechanisms of both the activation methods. 

In anisotropic crystallographic wet chemical etching of silicon, the dependency of the etch rate on crystal orientation is exploited. Even along the main levels of the crystal, for example along the (111) and (110) levels, the etch rate can vary by a factor of 100. Aqueous solutions of alkaline hydroxides such as KOH and NaOH are anisotropic etch solutions for silicon. The etching speed in individual directions will depend on the temperature and the etch solution used. The relation of the etch rate to the crystal s direction is shown in Figure 2.8 for the widely produced wafers made of (10 0)-type silicon [3]. 

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