Carbonate ions reactions

Hydroxide ion lies below phenol m Table 1 7 hydrogen carbonate ion lies above phe nol The practical consequence of the reactions shown is that NaOH is a strong enough base to convert phenol to phenoxide ion but NaHCOs is not... 

Many important biochemical reactions involve Lewis acid Lewis base chemistry Carbon dioxide is rapidly converted to hydrogen carbonate ion m the presence of the enzyme carbonic anhydrase... 

The nucleophilic portion of the reagent (Y m HY) becomes bonded to the p carbon For reactions carried out under conditions m which the attacking species is the anion Y an enolate ion precedes the enol... 

Weak to moderate chemiluminescence has been reported from a large number of other Hquid-phase oxidation reactions (1,128,136). The Hst includes reactions of carbenes with oxygen (137), phenanthrene quinone with oxygen in alkaline ethanol (138), coumarin derivatives with hydrogen peroxide in acetic acid (139), nitriles with alkaline hydrogen peroxide (140), and reactions that produce electron-accepting radicals such as HO in the presence of carbonate ions (141). In the latter, exemplified by the reaction of h on(II) with H2O2 and KHCO, the carbonate radical anion is probably a key intermediate and may account for many observations of weak chemiluminescence in oxidation reactions. 

The lime or lime—soda process results in the precipitation of calcium as calcium carbonate and magnesium as magnesium hydroxide. The solubiUties of these compounds are shown in Figure 4 as functions of pH. When lime is used alone, only the carbonate hardness is reduced. The carbonate hardness is present as calcium or magnesium bicarbonate. The additional use of soda ash can reduce the noncarbonate hardness by providing additional carbonate ion. The reactions involved in the various steps of the process are Hsted below ... 

Carbonylation, or the Koch reaction, can be represented by the same equation as for hydrocarboxylation. The catalyst is H2SO4. A mixture of C-19 dicarboxyhc acids results due to extensive isomerization of the double bond. Methyl-branched isomers are formed by rearrangement of the intermediate carbonium ions. Reaction of oleic acid with carbon monoxide at 4.6 MPa (45 atm) using 97% sulfuric acid gives an 83% yield of the C-19 dicarboxyhc acid (82). Further optimization of the reaction has been reported along with physical data of the various C-19 dibasic acids produced. The mixture of C-19 acids was found to contain approximately 25% secondary carboxyl and 75% tertiary carboxyl groups. As expected, the tertiary carboxyl was found to be very difficult to esterify (80,83). 

Verify that the position of equilibrium for the reaction between phenol and hydroxide ion lies to the right by comparing the pK of the acid on the left to the acid on the right. Which acid is stronger Do the same for the reaction of phenol with hydrogen carbonate ion. 

When a Br nsted base functions catalytically by sharing an electron pair with a proton, it is acting as a general base catalyst, but when it shares the electron with an atom other than the proton it is (by definition) acting as a nucleophile. This other atom (electrophilic site) is usually carbon, but in organic chemistry it might also be, for example, phosphorus or silicon, whereas in inorganic chemistry it could be the central metal ion in a coordination complex. Here we consider nucleophilic reactions at unsaturated carbon, primarily at carbonyl carbon. Nucleophilic reactions of carboxylic acid derivatives have been well studied. These acyl transfer reactions can be represented by... 

The Pf and M,. tests are designed to establish the concentration of hydroxyl, bicarbonate, and carbonate ions in the aqueous phase of the mud. At a pH of 8.3, the conversion of hydroxides to water and carbonates to bicarbonates is essentially complete. The bicarbonates originally present in solution do not enter the reactions. 

One of the features that makes the hydrobora ( ion reaction so useful is the regiochemistry that results when an unsymmetrical alkene is hydroborated. For example, hydroboration/oxidation of 1-methylcyclopentene yields trans-2-methylcydopentanol. Boron and hydrogen both add to the alkene from the same face of the double bond—that is, with syn stereochemistry, the opposite of anti—with boron attaching to the less highly substituted carbon. During the oxidation step, the boron is replaced by an -OH with the same stereochemistry, resulting in an overall syn non-Markovnikov addition of water. This stereochemical result is particularly useful because it is complementary to the Markovnikov regiochemistry observed for oxymercuration. 

As pointed out in Section 13.5, anions that are the conjugate bases of weak acids act themselves as weak bases in water They accept a proton from a water molecule, leaving an Oil ion that makes the solution basic. The reactions of the fluoride and carbonate ions are typical ... 

The similarities among the hydroxides are obvious. Let s compare sodium carbonate and ammonia. Sodium carbonate, Na2C03, dissolves in water to give a solution with the properties that identify a base. Quantitative studies of the solubilities of carbonates show that carbonate ion, C03-2, can react with water. The reactions are... 

Reaction (25) indicates that the presence of carbonate ion in water increases the hydroxide ion, OH-, concentration. This is a constituent that is present in the solutions of NaOH, KOH, MgCOH), and Ca(OH)j. 

The combination of reaction (18) and (16) shows how carbon dioxide enhances the solubility of calcium carbonate by removing carbonate ion to form bicarbonate ion,... 

Titration of carbonate ion with a strong acid. A solution of sodium carbonate may be titrated to the hydrogencarbonate stage (i.e. with one mole of hydrogen ions), when the net reaction is ... 

There are two additional pulse radiolysis investigations of Pu(VI) reactions that are of importance. These are the rate of reaction of e (aq) with Pu(VI) adsorbed on Si02 colloids and the rate of the reaction between Pu(V) and the carbonate ion radical... 

The complexation of Pu(IV) with carbonate ions is investigated by solubility measurements of 238Pu02 in neutral to alkaline solutions containing sodium carbonate and bicarbonate. The total concentration of carbonate ions and pH are varied at the constant ionic strength (I = 1.0), in which the initial pH values are adjusted by altering the ratio of carbonate to bicarbonate ions. The oxidation state of dissolved species in equilibrium solutions are determined by absorption spectrophotometry and differential pulse polarography. The most stable oxidation state of Pu in carbonate solutions is found to be Pu(IV), which is present as hydroxocarbonate or carbonate species. The formation constants of these complexes are calculated on the basis of solubility data which are determined to be a function of two variable parameters the carbonate concentration and pH. The hydrolysis reactions of Pu(IV) in the present experimental system assessed by using the literature data are taken into account for calculation of the carbonate complexation. 

With growing interest in the chemical behaviour of actinide ions in the environment (1), the complexation of these ions with carbonate anions has been recently attracting particular attention (2-10) due to the ubiquitous presence of carbonate ions in nature (11, 12) and their pronounced tendency to form complexes with heavy metal ions (7, 10-14). In spite of the carbonate complexation of actinides being considered important chemical reactions for understanding the chemistry of actinides in natural fluids, not many experiments have been devoted up to now to the quantitative study of the subject, though numerous qualitative observations are discussed in the literature. Although there are a few papers reporting the formation constants of carbonate complexes... 

Hydrolysis reactions. As the system under investigation contains not only carbonate ions but also hydroxide ions of considerable concentration, it is quite plausible that the reactions of hydrolysis and carbonate complex formation compete with each other. Since the hydrolysis reaction is not investigated separately in this experiment, the magnitude of this reaction as a function of pH is evaluated on the basis of the formation constants available in the literature (18), which are reproduced... 

The existence of such a process can be indirectly evidenced by the irregular change of decrement observed in free carbonate (also bicarbonate) concentrations near pH = 10 as illustrated in Figure 3. This may be ascribed to the consumption of free carbonate ions for the formation of the plutonium hydroxocarbonate precipitate. The reactions involved in this process are interpreted as follows ... 

Sodium hydrogen carbonate, NaHC03 (sodium bicarbonate), is commonly called bicarbonate of soda or baking soda. The rising action of baking soda in batter depends on the reaction of a weak acid, HA, with the hydrogen carbonate ions ... 

Among special chemical methods that facilitate the Diels-Alder reaction can be included the temporary metal connection strategy [101] that is illustrated in Table 4.27. Si, Mg and A1 are used as temporary connectors of diene and dienophile moieties. The cycloaddition occurs easily due to its intramolecular nature and because the dienophilic component of reagent is now formally a vinyl carbon ion (i.e. a vinyl carbanion in 154 with M = AlEt ). Thus the metal-tethered 154, prepared from lithium alkoxide of 153 with the suitable metal vinyl halide, gives, by heating, the cycloadducts 156 and 157, through the... 

Alkyl halides can be hydrolyzed to alcohols. Hydroxide ion is usually required, except that especially active substrates such as allylic or benzylic types can be hydrolyzed by water. Ordinary halides can also be hydrolyzed by water, if the solvent is HMPA or A-methyl-2-pyrrolidinone." In contrast to most nucleophilic substitutions at saturated carbons, this reaction can be performed on tertiary substrates without significant interference from elimination side reactions. Tertiary alkyl a-halocarbonyl compounds can be converted to the corresponding alcohol with silver oxide in aqueous acetonitrile." The reaction is not frequently used for synthetic purposes, because alkyl halides are usually obtained from alcohols. 

It is well established that sulfur compounds even in low parts per million concentrations in fuel gas are detrimental to MCFCs. The principal sulfur compound that has an adverse effect on cell performance is H2S. A nickel anode at anodic potentials reacts with H2S to form nickel sulfide. Chemisorption on Ni surfaces occurs, which can block active electrochemical sites. The tolerance of MCFCs to sulfur compounds is strongly dependent on temperature, pressure, gas composition, cell components, and system operation (i.e., recycle, venting, and gas cleanup). Nickel anode at anodic potentials reacts with H2S to form nickel sulfide. Moreover, oxidation of H2S in a combustion reaction, when recycling system is used, causes subsequent reaction with carbonate ions in the electrolyte [1]. Some researchers have tried to overcome this problem with additional device such as sulfur removal reactor. If the anode itself has a high tolerance to sulfur, the additional device is not required, hence, cutting the capital cost for MCFC plant. To enhance the anode performance on sulfur tolerance, ceria coating on anode is proposed. The main reason is that ceria can react with H2S [2,3] to protect Ni anode. 

In aerated pulps, carbonate ions are present these partake in the replacement reaction as shown below ... 

The feasibility of the above reaction ensues from the data on the solubility products of lead sulfate and lead carbonate salts. Evidence abounds that both sulfate and carbonate ions are present. 

In the human body, carbon dioxide provides the buffer. This is called the carbonic acid-hydrogen carbonate ion buffer system. This buffer system maintains the body s blood pH within acceptable levels. The main threat to the bloods pH is excess hydrogen ions produced by various chemical reactions in the body. When hydrogen ions are produced, hydrogen carbonate ions in the blood pick them up and convert them to carbonic acid ... 

When calcium carbonate goes into solution, it releases basic carbonate ions (COf ), which react with hydrogen ions to form carbon dioxide (which will normally remain in solution at deep-well-injection pressures) and water. Removal of hydrogen ions raises the pH of the solution. However, aqueous carbon dioxide serves to buffer the solution (i.e., re-forms carbonic acid in reaction with water to add H+ ions to solution). Consequently, the buffering capacity of the solution must be exceeded before complete neutralization will take place. Nitric acid can react with certain alcohols and ketones under increased pressure to increase the pH of the solution, and this reaction was proposed by Goolsby41 to explain the lower-than-expected level of calcium ions in backflowed waste at the Monsanto waste injection facility in Florida. 

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