Sequestering agents

Gluconic acid and other hydroxy acids act similarly. Sequestering agents are used extensively, e.g. for preventing deleterious catalytic effects of traces of Fe or Cu and in analysis. 

Many stabilizer systems have been tailored to a particular industry need or for particular areas where dilution water quaUty is poor. These grades are heavily stabilized and may contain organic sequestering agents, ie, staimate, phosphates, and nitrate ions, so that the weak solutions produced by dilution from hard water retain acceptable stabihty. The nitrate is not a stabilizer, but it inhibits corrosion of aluminum storage tanks by chloride ion. 

The chlorination of toluene in the absence of catalysts that promote nuclear substitution occurs preferentially in the side chain. The reaction is promoted by free-radical initiators such as ultraviolet light or peroxides. Chlorination takes place in a stepwise manner and can be controlled to give good yields of the intermediate chlorination products. Small amounts of sequestering agents are sometimes used to remove trace amounts of heavy-metal ions that cause ring chlorination. 

Direct reaction of formaldehyde cyanohydrin and ethylenediamine in the presence of a sulfuric acid catalyst gives ethylenediarninetetraacetonitrile [5766-67-6], hydrolysis of which leads to ethylenediarninetetraacetic acid [60-00-4] (EDTA), a widely used sequestering agent (26). 

Much of the work that led to elucidating the role of budders as calcium sequestering agents in detergency was done in connection with redeposition studies (34). 

Because of the need for basic initiators, cyanoacrylate adhesives do not perform well on acidic surfaces, such as wood. However, the addition of sequestering agents, such as crown ethers [30], 10, or calixarenes [31], 11, and others [32] to the adhesive improves the reactivity of the adhesive on less active surfaces. 

It is assumed that the sequestering agents can complex with trace amounts of... 

As a sequestering agent, it attaches to calcium ions in water, which keeps them from interfering with detergents and soaps. 

The sequestering agent tetrasodium pyrophosphate (TSPP) removes calcium and magnesium from the saliva, so they can t deposit on teeth as insoluble deposits called tartar (calcified plaque). In this respect it acts as a water-softening agent. However, it won t remove tartar that already exists. 

Scarlet GN, 119. See also FD C Red 4 scopalomine, 178 SD-40, 56, 70, 174 SD alcohol 40-B. See ethanol SDIC. See sodium dichloroisocyanurate seaweed extract. See agar, carrageenan sequestering agents, 19,49-54,242. See also water softeners serine, 123... 

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