Base combined with acids

Table 1 Hsts many of acetamide s important physical properties. Acetamide, CH2CONH2, dissolves easily ia water, exhibiting amphoteric behavior. It is slow to hydroly2e unless an acid or base is present. The autodissociation constant is about 3.2 x 10 at 94°C. It combines with acids, eg, HBr, HCl, HNO, to form soHd complexes. The chemistry of metal salts ia acetamide melts has been researched with a view to developing electroplating methods. The hterature of acetamide melts and complexes, their electrochemistry and spectroscopy, has been critically reviewed (9).

The base is extracted with ether, dried with potassium carbonate, the ether removed by distillation and the residue fractionated. The 4-(5 -diethylaminopentyl-2 -amino)-7-chloro-quinoline (BP 212° to 2l4°C/0.2 mm) is obtained. On cooling the compound solidifies crystalline. It melts, recrystallized from benzene, at BB°C. The base combines with phosphoric acid to yield a diphosphate salt. 

The diazohydroxide, which is formed from the diazonium hydroxide by isomerisation, is said to he the pseudo-base of the latter (Hantzsch), because although it is itself not a base (hut rather an acid) it nevertheless combines with acid to form. he diazonium salt. 

Wool and silk are protein-like substances and hence are amphoteric. Accordingly, they can combine with acids as well as with bases. For this reason wool and silk can be dyed directly by dyes in virtue of their auxochromic groups. 

Biguanides usually behave as mono- and di-acid bases, combining with H+ ions to form the conjugate acid, but may also act as acids. The acid dissociation constants of many biguanides have been measured, and are collected in Tables 1 and 2. 

The third method of separating optically active substances by combining them with optically active bases or acids had not been employed with any success until E. Fischer took up this question, the study of the optically active amino acids being his first work upon the chemical constitution of the proteins. The non-success of this method was in all probability due to the small affinity which the simple amino acids themselves have for combining with acids and bases even the attempts to separate the monoaminodicarboxylic acids, which are fairly strong acids, were not successful. 

Cytosine, thymine, and uracil are pyrimidines along with adenine and guanine they account for the five nucleic acid bases. Pyrimidines are heterocyclic single-ringed compounds based on the structure of pyrimidine. Cytosine, thymine, and uracil, like adenine and guanine, form nucleosides and nucleotides in RNA and DNA. When the bases combine with ribose, a ribo-nucleoside forms and when it attaches to deoxyribose, a deoxyribosenucleoside is formed. Names of the nucleoside are summarized in Table 29.1. These in turn combine with phospho-ryl groups, in a process called phosphorylation, to form their respective nucleotides that form nucleic acids. The nucleotides can be tri, di, and mono phosphate nucleotides similar to the way in which adenine forms ATP, ADP, and AMP. 

If one moves pn a step farther, binoxide of iln presente ltselfj a substance already more pronounced in its chemical character than charcoal. Still It is inclined to combine equally as well with bases as with acids, showing a transition character. Now, if pumice be soaked In a solution of bichloride of tin, and then dipped into a solution of carbonate of soda, the pumice acquires all the properties of animal charcoal. Very porous pumice, finely-divided silica, cotton fibre—all these show Bigne of chemical power depending on their extant of surface and it may well be supposed that this chemical power would he more prominent, could they be obtained in the fluid state. Silicic add, which is as inert as charcoal at the ordinary temperature, drives out the powerfal sulphuric acid from its combinations at a temperature nearer Its own melting point. 

What happens when you neutralize an acid with a base or a base with an acid The hydrogen atoms (H+ ions) of the acid combine with the hydroxyl groups (OH— ions) of the base to form water, and the metal atoms of the base combine with what remains of the acid to form a salt. Or simply ... 

Iodoso-compounds behave as diacid bases, e.g., C6H5I(OH)2, which combine with acids to form salts (Preparation 466). Reducing agents or... 

Antacids attempt to chemically neutralize stomach acids. These drugs typically contain a base such as carbonate or hydroxide combined with aluminum, magnesium, or calcium.34 The base combines with excess hydrogen ions (H+) in the stomach to increase intra-gastric pH. The basic strategy of this chemical neutralization is illustrated in Figure 27-1. 

For the reduction of water-soluble sulfur dyes, glucose and hydroxyacetone are also used [70], Glucose-based combinations with hydrosulfite, formamidine-sulfinic acid, and hydroxyacetone (binary reducing-agent systems) have gained acceptance for ecological, technical, and applicatory reasons [71], Mixtures of... 

Depolymerizing modification of starch usually involves the use of enzymes, acid- (and less frequently base-) catalyzed hydrolysis, and thermolysis alone and thermolysis combined with acid-catalyzed hydrolysis (see a recent survey in this Series2). Despite several studies, the physical treatment of starch has not yet resulted in major practical applications. The aim of this Chapter is to review physical methods as tools for the treatment of starch which deliver amounts of energy suitable for depolymerizing starch to target products. It should be noted that the duration of such processes does not need to exceed that for conventional, namely enzymic, chemical, and thermal modifications. Moreover, a potential advantage of nonconventional physical treatments is the fact that they generate no waste products. 

In a basic solution, the principle is similar. The conjugate acid of the weak base combines with excess hydroxide ion to drive the reaction toward the weak base. The same factors govern the process the amount of the conjugate acid and the Kb of the base. 

Base-catalysed H/D exchange experiments for a series of haloforms [80] (Table 4.10) demonstrate that carbanion formation is stabilised by halogen in the order 1 > Br > Cl > F. When these results are combined with acidity measurements which show that CF3H (pKa 31) is little more acidic than methane (pKa 40) [81], we can conclude that, in these systems, fluorine attached to a carbanion centre is stabilising with respect to hydrogen but destabilising compared with the effects of other halogens. Similar conclusions can be drawn from pKa measurements of a number of halobis(trifluoromethyl) methanes [82]. 

Amphoteric Hydroxides. A hydroxide, such as zinc hydroxide, which can combine with acids to form salts and also with bases to form salts is called an amphoteric hydroxide. The amphoteric properties of a metal hydroxide are determined by the stability of the hydroxide complex of the metal. 

The cinchona tree, from the bark of which these alkaloids are obtained, was originally found only on the eastern slope of the Andes in South America. The cultivation of this species, and other species of the same genus, was introduced into Java, India, Ceylon, Jamaica and Australia. At present the production of bark in Java is greater than in any other country. As early as 1639 the cinchona bark was introduced into Europe but it was not until 1792 that an impure alkaloid was isolated and a little later given the name quina. In 1820 this impure alkaloid was separated into two compounds named quinine and cinchonine. The bark contains about 3 per cent quinine combined with acids, tannic and quinic, from which it is set free by the action of lime. The free base is then extracted with petroleum ether or... 

In case (i) the current is expected to depend on pH in the shape of a dissociation curve in case (ii) the current would increase linearly with hydrogen ion concentration finally, for (iii), steadily increasing current, dependent on the buffer composition, would be observed. In practice either several dissociations or combinations of these factors are involved. The observed pH-dependence may show a U-shape or bell-shape, or a maximum. Sometimes the above-mentioned reactions are combined with acid-base reactions involving the electroactive form, of the type mentioned in the preceding paragraph. 

Examples of reactions in which acid-base catalysed dehydration was combined with acid-base equilibria either preceding or subsequent to the dehydration process are quoted for the waves of pyridine aldehydes (Tirouflet and Laviron, 1959 Volke, 1958 ManouSek and Zuman, 1964) and of glyoxalic acid (Kuta, 1959). Different dehydration rates were found for pyridinium ions and free pyridine derivatives, as well as for the free glyoxalic acid and its anion. For numerous aldehydic substances the effect of hydration has been observed but a quantitative treatment has not yet been applied. 

More forceful use of water-based decontamination technologies, alone or in combination with acidic interventions, may greatly contribute to enhanced meat safety, by modulation of resistance of E. coli 0157 H7 and other pathogens to acid. Water-based decontamination may also be rotated with acidic interventions (Samelis et al., 2002a). 

An independent method for demonstrating the involvement of carboxyl groups is based on the lower solid curve of the insert of Fig. 8 (a similar curve is shown in Fig. 7), which shows the difference between the instantaneous data (3-second) and the equilibrium (22-hour) data. Thus it should represent a product of two functions of pH ) the fraction of the total protein at equilibrium in which 36 groups have been liberated, and (2) the fraction of the new groups which combine with acid at the same... 

Recently published data on the cleavage of horse-radish peroxidase (Maehly, 1952, 1953), although indicating other complexities, bear sufficient resemblance to the situation described above for ferrihemoglobin, to raise a strong presumption that cleavage is accompanied by the liberation of prototropic groups unavailable for combination with acid and base in the native enzyme. No direct titration data are available for comparison. 

Base In chemistry, the nonadd part of a salt a substance that combines with acids to form salts a substance that dissociates to give hydroxide ions in aqueous solutions a substance whose molecule or ion can combine with a proton (hydrogen ion) a substance capable of donating a pair of electrons (to an acid) for the formation of a coordinate covalent bond. [EU]... 

It is a colorless, mobile liqmd. having a peculiar, very penetrating odor. It boils at 115 (239 R). It mixes with water in all proportiona It is strongly alkaline, and combines with acids as does NH,. like all the bases of this series, it is very stable, and withstands the action of such oxidizing agents as fuming HNO, and chromic acid. It forms crystaUine... 

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