Ammonium chloride catalysis

Copolymers of diallyl dimethyl ammonium chloride [7398-69-8] with acrylamide have been used in electroconductive coatings (155). Copolymers with acrylamide made in activated aqueous persulfate solution have flocculating activity increasing with molecular weight (156). DADM ammonium chloride can be grafted with cellulose from concentrated aqueous solution catalysis is by ammonium persulfate (157). Diallyl didodecylammonium bromide [96499-24-0] has been used for preparation of polymerized vesicles (158). 

Reactions of the Side Chain. Benzyl chloride is hydrolyzed slowly by boiling water and more rapidly at elevated temperature and pressure in the presence of alkaHes (11). Reaction with aqueous sodium cyanide, preferably in the presence of a quaternary ammonium chloride, produces phenylacetonitrile [140-29-4] in high yield (12). The presence of a lower molecular-weight alcohol gives faster rates and higher yields. In the presence of suitable catalysts benzyl chloride reacts with carbon monoxide to produce phenylacetic acid [103-82-2] (13—15). With different catalyst systems in the presence of calcium hydroxide, double carbonylation to phenylpymvic acid [156-06-9] occurs (16). Benzyl esters are formed by heating benzyl chloride with the sodium salts of acids benzyl ethers by reaction with sodium alkoxides. The ease of ether formation is improved by the use of phase-transfer catalysts (17) (see Catalysis, phase-thansfer). 

A fascinating area is micellar autocatalysis reactions in which surfactant micelles catalyse the reaction by which the surfactant itself is synthesized. Thus synthesis of dimethyldoceylamino oxide (reaction between dimethyl dodecyl amine and H2O2) benefits from this strategy. Here an aqueous phase can be used and an organic solvent can be avoided. Synthesis of mesoporous molecular sieves benefit through micellar catalysis and silicate polymerization rates have been increased by a factor 2000 in the presence of cetyltrimethyl ammonium chloride (Rathman, 1996). 

The silylated tin compound 199, obtained from tributyltin hydride and N-bis(trimethylsilyl)propargylamine (198) in the presence of a trace of AIBN (2,2/-azobisisobutyronitrile), is a versatile reagent for the preparation of allylic amines. Treatment with aryl bromides ArBr (Ar = Ph, 4-MeOCgH4, 4-O2NC6H4 etc.) under Pd(PPh3)4 catalysis yields the silylated amines 200, which are hydrolysed by acids to the free amines 201. 199 is converted into the lithium compound 202, which is transformed into 203 by aqueous ammonium chloride and into 204 by the action of alkyl halides RX (R = Me, Et or allyl) (equation 76)204. 

Furthermore, the use of a Lewis acid promoter leads to increased stereoselectivities (Table 19, entry C)252,254. Compared to the aprotic reaction, where allyl silane was used instead of allyl bromide and indium chloride, an almost complete reversal of the diastereos-electivity was found. It was demonstrated recently that the Lewis acid catalysed allylation reaction can be carried out efficiently without any organic solvent in saturated ammonium chloride solution255. Finally, Lewis acid catalysed Mannich reactions can be carried out conveniently in mixtures of organic solvents and water. However, the exact role of the Lewis acid catalyst has not been clarified (Table 19, entry D)253. The same reaction can be carried out in pure water with catalysis by indium trichloride256. 

Attempted catalysis. A number of experiments were carried out to test the possible catalytic activity of substances such as potassium carbonate, cupric carbonate, ammonium chloride, ammonium sulfate, potassium silicate, boron phosphate, and silica gel, but in no case was there any indication that the reaction could be catalyzed. 

One of the oldest techniques for overcoming these problems is the use of biphasic water/organic solvent systems using phase-transfer methods. In 1951, Jarrouse found that the reaction of water-soluble sodium cyanide with water-insoluble, but organic solvent-soluble 1-chlorooctane is dramatically enhanced by adding a catalytic amount of tetra-n-butylammonium chloride [878], This technique was further developed by Makosza et al. [879], Starks et al. [880], and others, and has become known as liquid-liquid phase-transfer catalysis (PTC) for reviews, see references [656-658, 879-882], The mechanism of this method is shown in Fig. 5-18 for the nucleophilic displacement reaction of a haloalkane with sodium cyanide in the presence of a quaternary ammonium chloride as FT catalyst. 

Catalysis B and D were obfained from a commercial plant for cafalysf production. The production methods were similar to catalyst C but more simple. Catalyst E was obtained in the same manner as catalyst A, except that cetylpyridinium chloride was replaced by cetyltrimethyl ammonium chloride. 

Balakrishnan, T., S. Hari Babu, and T. K. Shabeer, Triphase Catalysis 11. Alkylation of Phenylacetone with 1-Bromobutane Catalyzed by Aqueous NaOH and Polystyrene-Supported Benzyl-trethyl Ammonium Chloride, l.Pofy. ScL, Part A Poly. Cheat, 31, 317(1993). 

Phase-transfer catalysis. A Polish group reported that the Wittig-Horner reaction with a-phosphoryl sulfoxides, sulfones, and sulfides could be conducted in a two-phase system (aqueous NaOH-methylene chloride) with benzyltriethyl-ammonium chloride as catalyst. Later work showed that a catalyst was not necessary because these sulfur compounds themselves can function as catalysts for phase-transfer reactions. Thus (1) is an effective catalyst for alkylation of ketones by alkyl halides in the presence of 50% aqueous NaOH. Related, but somewhat less active, catalysts are sulfones such as (2), a-disulfoxides (3), and bisphosphonates (4). 

Recently, two methods were published that have attracted some interest, because no metal salts are necessary as oxidation reagents. Shi and Xu (1990) found that substituted (trifluoromethyl)-diazoalkanes (CF3CRN2, R = alkyl or aryl) are obtained by refluxing trifluoromethyl ketones and 2,4,6-tri(isopropyl)benzenesulfonyl hydrazone in a methanolic solution of KOH. Kumar (1991) synthesized a-diazocar-bonyl compounds under tri-phase phase-transfer catalysis using a polystyrene-supported (tributyl)(methyl)-ammonium chloride catalyst, methanesulfonyl chloride, NaN3, and methylsulfonyl azide in 1,2-dichloroethane and a carbonyl-activated substrate (69-94% yield). 

Nevertheless, phase-transfer catalysis is an advantageous method for diazo transfer reactions, as mentioned previously for cyclic a-diazo ketones (Lombardo and Mander, 1980) and shown also by Starks (1971) and Ledon (1974). Di( er -butyl) malonate reacts with 4-toluenesulfonyl azide in methylene chloride and in the presence of a small amount (2 mol- o) of methyl(trioctyl)ammonium chloride as phase-transfer catalyst. After workup with aqueous NaOH A tert-hviiy ) diazomalonate is obtained in 59-63% yield, whereas without phase-transfer catalysis the yield is only 47 % after a reaction time of 4 weeks The procedure is described in Organic Syntheses (Ledon, 1988). Diazo transfer to malonates and vinylogous malonates has also been investigated by Davies et al. (1985). 

The best known example of heterogeneous catalysis in such systems is the preparation of [Co(NH3)6]Cl3. The air oxidation of a reaction mixture of aqueous cobalt(n) chloride, excess ammonia, and ammonium chloride, followed by acidification with excess hydrochloric acid, yields largely [Co(NH3)5Cl]Cl2, reaction (24). Under the same conditions, in the presence... 

A successful quantitative analysis of the reaction between aquated nickel(ii) ions and azo(2-pyridine)4 -N,N-dimethylaniline (46) in sodium lauryl sulphate leads to conclusions that catalysis occurs at the micellar surface and is due entirely to concentration of the reactants (Figure 4). Addition of sodium chloride (sodium ions are claimed to be completely displaced by nickel ions at the micelle surface) decreases the reaction rate marginally but tetraethyh ammonium chloride has a much more pronounced inhibitory effect. The reaction characteristics were found to be strongly dependent on the source of sodium lauryl sulphate. There is significant catalysis below the c.m.c. if both... 

V-Substituted glycosylamines having aliphatic amines and substituted anilines as aglycons are prepared simply by reaction of the amine and aldose, or acetylated aldose, in aqueous or alcoholic solution (5, 10, H, 26a, 32). The preparation of V-p-tolyl- or V-phenyl-D-fructosylamine requires acid catalysis, better results being obtained by the use of the amine hydrochloride as the catalyst than of ammonium chloride (23). Acid catalysis may also be necessary for ketoses and to condense certain weak amines and urea with aldoses (33) but often may be unnecessary and even undesirable (34)-... 

With a more powerful nucleophile such as potassium thioacetate, the reaction is much easier proceeding even with a dilute aqueous solution of the nucleophile under phase transfer conditions. Best results are obtained under solid-liquid phase transfer catalysis with essentially complete conversion obtained with both tetrabutyl ammonium chloride and 18-crown-6. A critical evaluation of this and further data reported by Nishikubo and coworkers (Ref. 19, 20) leads to the following general conclusions ... 

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