Sequestrants acid

ETHYLENEDINITRILOTETRAACETIC ACID HAMP-ENE ACID HAVIDOTE METAQUEST A NERVANAID B ACID NULLAPON BE ACID PER.MA KLEER 50 ACID QUESTEX4H SEQ 100 SEQUESTRENE AA SEQUESTRIC ACID SEQUESTROL TETRINEACID TITRIPLEX TRICON BW TRILON BW VERSENE ACID VINKEIL 100 WARKEELATEACID... 

SEQUESTRIC ACID (60-00-4) Incompatible with sulfuric acid, bases, ammonia, aliphatic amines, alkanolamines, isocyanates, alkylene oxides, epichlorohydrin. 

Concentrations above 0.3% form a gel with borate which is reversible upon the subsequent addition of mannitol (a sequestrant for borate) or of acid. Usefiil combinations are formed with carrageenan (63) and xanthan gum (64) and agar. In many appHcations, it is used in combination with these gums at considerable cost savings. 

Phosphonic acid is an intermediate in the production of alkylphosphonates that are used as herbicides and as water treatment chemicals for sequestration, scale inhibition, deflocculation, and ion-control agents in oil weUs, cooling tower waters, and boiler feed waters. For example, aqueous phosphonic acid reacts with formaldehyde and ammonium chloride in the presence of hydrochloric acid to yield aminotri(methylenephosphonic acid) [6419-19-8]. 

Organophosphoms compounds, primarily phosphonic acids, are used as sequestrants, scale inhibitors, deflocculants, or ion-control agents in oil wells, cooling-tower waters, and boiler-feed waters. Organophosphates are also used as plasticizers and flame retardants in plastics and elastomers, which accounted for 22% of PCl consumed. Phosphites, in conjunction with Hquid mixed metals, such as calcium—zinc and barium—cadmium heat stabilizers, function as antioxidants and stabilizer adjutants. In 1992, such phosphoms-based chemicals amounted to slightly more than 6% of all such plastic additives and represented 8500 t of phosphoms. Because PVC production is expected to increase, the use of phosphoms additive should increase 3% aimually through 1999. 

Bile Acid Sequestrants. The bile acid binding resins, colestipol [26658424] and cholestyramine, ate also effective in controlling semm cholesterol levels (150). Cholestyramine, a polymer having mol wt > ICf, is an anion-exchange resin. It is not absorbed in the gastrointestinal tract, is not affected by digestive enzymes, and is taken orally after being suspended in water (151). 

Deprotonation of enols of P-diketones, not considered unusual at moderate pH because of their acidity, is faciUtated at lower pH by chelate formation. Chelation can lead to the dissociation of a proton from as weak an acid as an aUphatic amino alcohol in aqueous alkaU. Coordination of the O atom of triethanolamine to Fe(III) is an example of this effect and results in the sequestration of iron in 1 to 18% sodium hydroxide solution (Fig. 7). Even more striking is the loss of a proton from the amino group of a gold chelate of ethylenediamine in aqueous solution (17). 

Many reactions catalyzed by the addition of simple metal ions involve chelation of the metal. The familiar autocatalysis of the oxidation of oxalate by permanganate results from the chelation of the oxalate and Mn (III) from the permanganate. Oxidation of ascorbic acid [50-81-7] C HgO, is catalyzed by copper (12). The stabilization of preparations containing ascorbic acid by the addition of a chelant appears to be negative catalysis of the oxidation but results from the sequestration of the copper. Many such inhibitions are the result of sequestration. Catalysis by chelation of metal ions with a reactant is usually accomphshed by polarization of the molecule, faciUtation of electron transfer by the metal, or orientation of reactants. 

Electrodeposition of Metals. Citric acid and its salts are used as sequestrants to control deposition rates in both electroplating and electroless plating of metals (153—171). The addition of citric acid to an electroless nickel plating bath results in a smooth, hard, nonporous metal finish. 

Phospha.tes, Pentasodium triphosphate [7758-29-4] sodium tripolyphosphate, STPP, Na P O Q, is the most widely used and most effective builder in heavy-duty fabric washing compositions (see also Phosphoric acid and phosphates). It is a strong sequestrant for calcium and magnesium, with a p c of ca 6, and provides exceUent suspending action for soils. Because of its high sequestration power, it also finds extensive appHcation in automatic-dishwashing detergents. Sodium tripolyphosphate forms stable hydrates and thus aids in the manufacture of crisp spray-dried laundry powders. 

Sequestrants. These protect SBR latex from ions through complex formation. EDTA (ethylenediamine tetraacetic acid) is the most common. 

Ligands bite at one or more points. Chelants bite at two or more points, so all ligands are not necessarily chelants. Chelants forming water-soluble complexes with metal ions are called sequestrants (but not all sequestrants are chelants). The most commonly employed BW chelant, ethylenediaminetetraacetic acid (EDTA) produces coordination complexes with four points of attachment and is termed a tetraden-tate ligand. 

Aminotri(methylenephosphonic acid) [ATMP or AMP] is the least expensive phosphonate. It is a good, general-purpose, cost-effective scale inhibitor an effective chelant and the most thermally stable of all the common phosphonates. It is satisfactory up to at least 700 psia. However, if fed as a concentrate AIMP may easily form insoluble calcium phosphonate and it may also affect copper. ATMP has a sequestration value of 870 mg CaC03/g product at a pH level of 11 and for iron, a sequestration value of 150 mg Fe/g product at a pH level of 10. The pentasodium salt has a MW of 409. Examples include Dequest 2000/2006, Mayoquest 1230, Phos -2, Briquest 301-50A, Unihib 305, and Codex 8503. 

Phosphonobutane-l,2,4-tricarboxylic acid (PBTC) is the most expensive of the commonly used phosphonates. However it is excellent at providing calcium carbonate control under highly stressed operating conditions. It is most resistant to the problem of calcium phosphonate precipitation and, from an environmental position, has the lowest phosphorus content of the common phosphonates. The acid material has a MW of 270. PBTC has a sequestration value of 280 mg CaC03/g product at a pH level of 11. It is very stable and can operate under very high pH conditions. However, it may also attack copper. Examples include Bayhibit AM, Mayoquest 2100, Phos -9, and Codex 551. 

Diethylenetriaminepenta (methylene phosphonic acid) [DETPMP] is the most effective sequestrant for barium sulfate. DETPMP has a sequestration value of 820 mg CaC03/g product at pH 11. The hexa-sodium salt has MW of 705. Examples include Dequest 2066 and Mayoquest 1860. 

Cliolestyramine (Questran) and colestipol (Colestid) are examples of bile acid sequestrants. Bile, which is manufactured and secreted by the liver and stored in the gallbladder, emulsifies fat and lipids as these products pass through the intestine Once emulsified, fats and lipids are readily absorbed in the intestine These drug bind to bile acids to form an insoluble substance that cannot be absorbed by the intestine, so it is secreted in the feces. With increased loss of bile acids, the liver uses cholesterol to manufacture more bile This is followed by a decrease in cholesterol levels. 

The bile acid sequestrants are used as adjunctive therapy for the reduction of elevated serum cholesterol in patients with hypercholesterolemia who do not have an... 

A common problem associated with the administration of the bile acid sequestrants is constipation. Constipation may be severe and may occasionally result in fecal impaction. Hemorrhoids may be aggravated. Additional adverse reactions include vitamin A and D deficiencies, bleeding tendencies (including gastrointestinal bleeding) caused by a depletion of vitamin K, nausea, abdominal pain, and distention. 

The bile acid sequestrants are contraindicated in patients with known hypersensitivity to the drugs. Bile acid sequestrants are also contraindicated in those with complete biliary obstruction. These drags are used cautiously in patients with a history of liver or kidney disease Bile acid sequestrants are used cautiously during pregnancy (Pregnancy Category C) and lactation (decreased absorption of vitamins may affect the infant). 

The HMG-CoA reductase inhibitors have an additive effect when used with the bile acid sequestrants, which may provide an added benefit in treating hypercholesterolemia that does not respond to a single-drug regimen. There is an increased risk of myopathy (disorders of the striated muscle) when the HMG-CoA reductase inhibitors are administered with erythromycin, niacin, or cyclosporin a When the HMG-CoA reductase inhibitors are administered with oral anticoagulants, there is an increased anticoagulant effect. 

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