Triethanolamin

Here the ethylene oxide undergoes parallel reactions, whereas the monoethanolamine undergoes a series reaction to diethanolamine and triethanolamine. 

Two principal secondary reactions occur, to diethanolamine and triethanolamine ... 

The secondary reactions are parallel with respect to ethylene oxide but series with respect to monoethanolamine. Monoethanolamine is more valuable than both the di- and triethanolamine. As a first step in the flowsheet synthesis, make an initial choice of reactor which will maximize the production of monoethanolamine relative to di- and triethanolamine. 

Solution We wish to avoid as much as possible the production of di- and triethanolamine, which are formed by series reactions with respect to monoethanolamine. In a continuous well-mixed reactor, part of the monoethanolamine formed in the primary reaction could stay for extended periods, thus increasing its chances of being converted to di- and triethanolamine. The ideal batch or plug-flow arrangement is preferred, to carefully control the residence time in the reactor. 

The use of an excess of ammonia is home out in practice. A mole ratio of ammonia to ethylene oxide of 10 1 3delds 75 percent monoethanolamine, 21 percent diethanolamine, and 4 percent triethanolamine. Using equimolar proportions under the same reaction conditions, the respective proportions become 12, 23, and 65 percent. 

Another possibility to improve selectivity is to reduce the concentration of monoethanolamine in the reactor by using more than one reactor with intermediate separation of the monoethanolamine. Considering the boiling points of the components given in Table 2.3, then separation by distillation is apparently possible. Unfortunately, repeated distillation operations are likely to be very expensive. Also, there is a market to sell both di- and triethanolamine, even though their value is lower than that of monoethanolamine. Thus, in this case, repeated reaction and separation are probably not justified, and the choice is a single plug-flow reactor. 

The 5-nitrosallcylaldehyde reagent is prepared as follows. Add 0-5 g. of 5-nitrosalicylaldehyde (m.p. 124-125°) to 15 ml. of pure triethanolamine and 25 ml. of water shake until dissolved. Then introduce 0-5 g. of crystallised nickel chloride dissolved in a few ml. of water, and dilute to 100 ml. with water. If the triethanolamine contains some ethanolamine (thus causing a precipitate), it may be necessary to add a further 0 - 5 g. of the aldehyde and to filter off the resulting precipitate. The reagent is stable for long periods. 

Direct Titrations. The most convenient and simplest manner is the measured addition of a standard chelon solution to the sample solution (brought to the proper conditions of pH, buffer, etc.) until the metal ion is stoichiometrically chelated. Auxiliary complexing agents such as citrate, tartrate, or triethanolamine are added, if necessary, to prevent the precipitation of metal hydroxides or basic salts at the optimum pH for titration. Eor example, tartrate is added in the direct titration of lead. If a pH range of 9 to 10 is suitable, a buffer of ammonia and ammonium chloride is often added in relatively concentrated form, both to adjust the pH and to supply ammonia as an auxiliary complexing agent for those metal ions which form ammine complexes. A few metals, notably iron(III), bismuth, and thorium, are titrated in acid solution. 

Br , citrate, CE, CN , E, NH3, SCN , S20 , thiourea, thioglycolic acid, diethyldithiocarba-mate, thiosemicarbazide, bis(2-hydroxyethyl)dithiocarbamate Acetate, acetylacetone, BE4, citrate, C20 , EDTA, E , formate, 8-hydroxyquinoline-5-sul-fonic acid, mannitol, 2,3-mercaptopropanol, OH , salicylate, sulfosalicylate, tartrate, triethanolamine, tiron... 

Br , citrate, CE, 2,3-dimercaptopropanol, dithizone, EDTA, E, OH , NagP30io, SCN , tartrate, thiosulfate, thiourea, triethanolamine BE4, citrate, V,V-dihydroxyethylglycine, EDTA, E , polyphosphates, tartrate Citrate, CN , 2,3-dimercaptopropanol, dimercaptosuccinic acid, dithizone, EDTA, glycine, E, malonate, NH3, 1,10-phenanthroline, SCN , 820 , tartrate Citrate, V,V-dihydroxyethylglycine, EDTA, E , PO , reducing agents (ascorbic acid), tartrate, tiron... 

Acetone, (reduction with) ascorbic acid, citrate, CE, CN , 2,3-dimercaptopropan-I-oI, EDTA, formate, E, 8CN , 80 , tartrate, thiosemicarbazide, thiourea, triethanolamine CE, EDTA, F , 8CN , tartrate, thiourea, triethanolamine Citrate, CN , 8CN , tartrate, thiourea Citrate, EDTA, F , oxalate, tartrate, tiron... 

Citrate, C20 , cycIohexane-I,2-diaminetetraacetic acid, V,V-dihydroxyethyIgIycine, EDTA, F , glycol, hexametaphosphate, OH , P20 , triethanolamine Citrate, CN , C20 , 2,3-dimercaptopropanol, EDTA, F , NagP30io, oxidation to MnOy, P20 , reduction to Mn(II) with NH2OH HCI or hydrazine, sulfosalicylate, tartrate, triethanolamine, triphosphate, tiron... 

NagPgOio, NH3, 1,10-phenanthroline, SCN , sulfosalicylate, thioglycolic acid, triethanolamine, tartrate... 

Tl Citrate, CE, CN , EDTA, HCHO, hydrazine, NH2OH HCl, oxalate, tartrate, triethanolamine... 

U Citrate, (NH4)2C03, C20 , EDTA, F , H2O2, hydrazine + triethanolamine, phosphate(3—),... 

H2O2, PO , P20 , pyrogallol, quinalizarinesulfonic acid, salicylate, SOJ + H2O2, sulfosalicylate, tartrate, triethanolamine... 

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