Manufacturing processes amphoterics

Lead Monoxide. Lead monoxide (litharge), PbO, occurs as a reddish alpha form, which is stable up to 489°C where it transforms to a yellow beta form (massicot). The latter is stable at high temperatures. The solubihty of a-PbO ia water is 0.0504 g/L at 25°C the solubihty of the p-PbO is 0.1065 g/L at 25°C (40). Lead monoxide is amphoteric and dissolves ia both acids and alkahes. In alkahes, it forms the plumbite ion PbO - The monoxide is produced commercially by the reaction of molten lead with air or oxygen ia a furnace. Black or gray oxide is manufactured by the Barton process, by the oxidation of atomized molten lead ia air, as well as by the ball mill process, ia which metallic lead balls of high purity are tumbled ia the mill to form partially oxidized lead particles. 

In a pilot plant or manufacturing facility, controls can be put into place in order to effect fine adjustment of processes. Processes requiring point-type conditions can be accommodated and must be controlled. For instance, the yield of 3-hydroxy-4-methoxypyrimidine (1, Figure 2.1) is sharply decreased by crystallization under conditions more acidic or more basic than pH 5.3, probably due to the amphoteric nature of this compound [3]. Reproducible yields were obtained on scale because the isolation conditions could be tightly controlled. 

The free-radical addition of TFE to pentafluoroethyl iodide yields a mixture of perfluoroalkyl iodides with even-numbered fluorinated carbon chains. This is the process used to commercially manufacture the initial raw material for the fluorotelomer -based family of fluorinated substances (Fig. 3) [2, 17]. Telomeri-zation may also be used to make terminal iso- or methyl branched and/or odd number fluorinated carbon perfluoroalkyl iodides as well [2]. The process of TFE telomerization can be manipulated by controlling the process variables, reactant ratios, catalysts, etc. to obtain the desired mixture of perfluoroalkyl iodides, which can be further purified by distillation. While perfluoroalkyl iodides can be directly hydrolyzed to perfluoroalkyl carboxylate salts [29, 30], the addition of ethylene gives a more versatile synthesis intermediate, fluorotelomer iodides. These primary alkyl iodides can be transformed to alcohols, sulfonyl chlorides, olefins, thiols, (meth)acrylates, and from these into many types of fluorinated surfactants [3] (Fig. 3). The fluorotelomer-based fluorinated surfactants range includes noiuonics, anionics, cationics, amphoterics, and polymeric amphophiles. 

A number of granted patents exist that cover preferred processes for manufacture of several classes of amphoterics, and cover advantageous surfactant blends. 

Carboxyamphoteric surfactants based on fatty alkyl imidazolines ( imidazolinium surfactants) make up a large part of the amphoteric surfactants. The very divergent interpretation of their chemical structure is partly attributable to little-developed analytical procedures in the past, but is also a consequence of special processing methods by different manufacturers. Materials of this surfactant class are based on the imidazolines obtained by the condensation of fatty acids, or their esters, with AEEA. In Figures 12.4 and 12.5, a summary of the synthesis of amphoteric surfactants based on imidazolines [4,8] is presented. 

Fatty amines and their derivatives represent the most important nitrogen compounds of fatty acids. They possess great ionization constants compared with other alkyl derivatives of ammonia. They are cationic, basic, biologically active, and strongly adsorbed on many surfaces due to their high adsorption potential. They are indispensable in many surface-related physicochemical processes. They are the starting materials for the manufacture of quaternary ammonium compounds and various cationic and amphoteric substances. 

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