Salt-free production

Salt is a by-product. Due to the stability of the amide group, the free acid can be formed and separated from the reaction mixture to give a salt-free product. The stability of the amide group also allows sarcosinates to be used in a wider range of chemical environments than isethionates (see below). Sarcosinates are stable under moderately acidic conditions but will degrade at low pH or with elevated temperature. The surfactants are moderately soluble at high pH and the sodium salts are supplied as a 30% solution. 

A process based on the ammoximation of cyclohexanone and on the catalyzed rearrangement of the oxime went on stream in Japan in 2003 it allows the salt-free production of s-caprolactam, at lower investment and operating costs than by conventional routes. 

An alternative route to sulfobetaines is the reaction of a tertiary amine with 1,3-propanesultone (Figure 15.9). This route leads to salt-free products. Since propane-sultone is a highly carcinogenic chemical, the products must be checked carefully for residual sultone content. The production of these propylsulfobetaines is limited to a few specialized producers. 

The apparatus shown in Figure 2.11 could be used, for example, to prepare fresh water from seawater, which can be considered a solution of sodium chloride in water. The seawater to be purified is placed in a round-bottomed distillation flask heated with an electrically powered heating mantle. The seawater is boiled and pure water vapor in the gaseous state flows into the condenser, where it is cooled and condensed back to a purified salt-free product in the receiving flask. When most of the seawater has been evaporated, the distillation flask and its contents are cooled and part of the sodium chloride separates out as crystals that can be removed. 

A commercially available acid zeolite has also been reported to be an efficient catalyst in the completely salt-free production of ureas. Reaction of aromatic amines with ethyl acetoacetate 1105 in the presence of HY zeolite HSZ-360 (1 g of zeolite/ 20 mmol of amine) under solvent-free conditions gives symmetrical diarylureas 1107 in good yields (58-77%) and with excellent selectivity (93-96%) through a straightforward procedure (route A). Acetone, ethanol, and traces of acetoacetani-hdes are the sole by-products [793]. 

The commercial method of preparation of trimethylbutylphenol [65, 66] or its calcium salt [67] has been reported. The process involves reacting slightly over 3.0 moles of formaldehyde with 1.0 mole of sodium phenate at low temperature. The salt-free product is obtained by neutralization with phosphoric acid and decantation from the salt solution. The product is mainly free of resinous material and has found use in laminates, adhesives [68], and foundry sand moWs [69]. 

Wittig reactions (Equation 3) in non-polar media can be initiated by solid-liquid phase transfer of potassium carbonate or t-butoxide with 18-crown-6. Typical salt-free product distributions (Z-disubstituted alkene predominant) are observed with non-stabilized ylidcs in THF, but they are surprisingly reversed in dichloro-methane solution. -Alkenes usually predominate in both solvents when stabilized ylides are involved. Two-phase Wittig-Horner syntheses of ajS-unsaturated sulphides etc. (Equation 5) are also crown-catalysed, as is the Darzens-type process (Equation 14). ... 

A production plant for salt-free ethyleneimine synthesis by catalytic dehydration of monoethanol amine [141-45-5] in the gas phase has started operation at the Japanese company Nippon Shokubai (366). 

Because monocalcium phosphate is incongmently soluble, it is typically contaminated with various amounts (6—10%) of dicalcium phosphate and free phosphoric acid resulting from in-process disproportionation of the monocalcium salt. Free phosphoric acid may render the product hygroscopic, and absorbed water plus acid catalyzes further decomposition to additional free acid and dicalcium phosphate. For this reason, industrial monocalcium phosphate may contain some dicalcium phosphate resulting from excess lime addition and then aged to ensure the removal of residual free phosphoric acid. 

EDA reacts with formaldehyde and sodium cyanide under the appropriate alkaline conditions to yield the tetrasodium salt of ethylenediaminetetraacetic acid (24). By-product ammonia is removed at elevated temperatures under a partial vacuum. The free acid or its mono-, di-, or trisodium salts can be produced by the appropriate neutrali2ation using a strong mineral acid. This same reaction with other amines is used to produce polyamino acetic acids and their salts. These products are used widely as chelating agents. 

Many of the surfactants made from ethyleneamines contain the imidazoline stmcture or are prepared through an imidazoline intermediate. Various 2-alkyl-imidazolines and their salts prepared mainly from EDA or monoethoxylated EDA are reported to have good foaming properties (292—295). Ethyleneamine-based imida zolines are also important intermediates for surfactants used in shampoos by virtue of their mildness and good foaming characteristics. 2- Alkyl imidazolines made from DETA or monoethoxylated EDA and fatty acids or their methyl esters are the principal commercial intermediates (296—298). They are converted into shampoo surfactants commonly by reaction with one or two moles of sodium chloroacetate to yield amphoteric surfactants (299—301). The ease with which the imidazoline intermediates are hydrolyzed leads to arnidoamine-type stmctures when these derivatives are prepared under aqueous alkaline conditions. However, reaction of the imidazoline under anhydrous conditions with acryflc acid [79-10-7] to make salt-free, amphoteric products, leaves the imidazoline stmcture essentially intact. Certain polyamine derivatives also function as water-in-oil or od-in-water emulsifiers. These include the products of a reaction between DETA, TETA, or TEPA and fatty acids (302) or oxidized hydrocarbon wax (303). The amidoamine made from lauric acid [143-07-7] and DETA mono- and bis(2-ethylhexyl) phosphate is a very effective water-in-od emulsifier (304). 

The oxidation products are almost insoluble and lead to the formation of protective films. They promote aeration cells if these products do not cover the metal surface uniformly. Ions of soluble salts play an important role in these cells. In the schematic diagram in Fig. 4-1 it is assumed that from the start the two corrosion partial reactions are taking place at two entirely separate locations. This process must quickly come to a complete standstill if soluble salts are absent, because otherwise the ions produced according to Eqs. (2-21) and (2-17) would form a local space charge. Corrosion in salt-free water is only possible if the two partial reactions are not spatially separated, but occur at the same place with equivalent current densities. The reaction products then react according to Eq. (4-2) and in the subsequent reactions (4-3a) and (4-3b) to form protective films. Similar behavior occurs in salt-free sandy soils. 

Some laxatives (e.g., bulk-forming agents) contain significant amounts of sodium or sugar and may be unsuitable for salt-restricted or diabetic patients. When low-sodium or sugar-free products are not used, monitor serum concentrations of sodium and glucose as needed with chronic use. 

The pigment is then laked according to the procedure described for [3-naphthol pigments (Sec. 2.7.1.1). Aluminum lakes are an exception. A soluble aluminum salt is first converted to aluminum oxide hydrate, which is washed to remove salt. The moist product is then combined with the dye solution, while a more soluble aluminum salt is added simultaneously. The insoluble pigment is finally washed salt-free and dried. 

Reactions.—Aldehydes. The stereochemistry of the alkene produced from ylides generated by using 18-crown-6 complexes of potassium carbonate or butoxide, depends upon the solvent used. In THF typical salt free distributions are obtained whereas in dichloromethane reversal of product distributions is observed.17 A simplified method (Scheme 4) for preparing para-substituted styrenes in high... 

Reactions of allylic electrophiles with stabilized carbon nucleophiles were shown by Helmchen and coworkers to occur in the presence of iridium-phosphoramidite catalysts containing LI (Scheme 10) [66,69], but alkylations of linear allylic acetates with salts of dimethylmalonate occurred with variable yield, branched-to-linear selectivity, and enantioselectivity. Although selectivities were improved by the addition of lithium chloride, enantioselectivities still ranged from 82-94%, and branched selectivities from 55-91%. Reactions catalyzed by complexes of phosphoramidite ligands derived from primary amines resulted in the formation of alkylation products with higher branched-to-linear ratios but lower enantioselectivities. These selectivities were improved by the development of metalacyclic iridium catalysts discussed in the next section and salt-free reaction conditions described later in this chapter. 

N-Boc-N-(but-2-enoyl)amine is an excellent pronucleophile for the Ir-catalyzed allylic amination under salt-free conditions (cf. Table 9.3, entries 15-18). The products were subjected to RCM with good results, even upon application of the Grubbs I catalyst (Scheme 9.29) [27bj. The resultant N-Boc protected a,P-unsaturated y-lactams are valuable chiral intermediates with appUcations in natural products synthesis and medicinal chemistry. 

Tellurophosphoranes, obtained through a transylidation reaction between tellurenyl halides and phosphoranes, react with aldehydes to give the expected vinylic tellurides as an E Z isomeric mixture (method a). One other methodology involves the treatment of equimolar amounts of phenyl tellurenyl bromide and phosphonium salts with t-BuOK followed by an aldehyde (method b). Under these lithium-salt-free conditions, (Z)-vinylic tellurides are the main products. ... 

In Hght of the hahde effects, the role of the copper afkoxide and the lithium halide, derived from the transmetaUation, was probed by preparing the copper afkoxide under salt-free conditions (Tab. 10.10) [24, 51, 52]. Initially, mesityl copper, from which the metal hahde salts are removed during preparation [53], was chosen to provide the copper(I) afkoxide. Interestingly, only a trace of product was observed in the absence of hthium... 

Over the years it has been shown that complexes prepared from organophosphorous ligands in combination with peroxotungstic acid or its quaternary ammonium salts exhibit efficient catalytic properties. In order to make an efficient recycling of the catalyst possible and get tungsten-free products and effluents, some of these catalysts were immobilized onto polystyrene, poly benzimidazole and polymethacrylate copolymers modified by the introduction of the phosphorous(V)-containing ligands. 

Free product, suspended solids, and highly turbid waste streams lower UV reactor efficiency. The CAV-OX process does not treat metals. It may, however, oxidize metallic ions or reduce metallic salts while destroying organic contaminants. The disadvantages of the CAV-OX process include high energy consumption, not cost effective at high contaminant concentrations, and the process mechanisms are not well documented. 

---