Aqueous medium reactions

Fragmentation of 143 is not limited to aqueous media. Reaction of threo-745 with cyclohexylamine, triethylamine, or 2,6-lutidine in acetonitrile also leads to (Z)-144 while the phosphorus appears in various polyphosphates, in the trimetaphosphate trianion (after 110 °C/5 h, before work-up), and in phosphoramidates 95). 

The nucleophilic addition-protonation mechanism is not confined to aqueous media. Reaction of phenylmethanesulfonyl-d2 chloride and triethylamine in the presence of triethylammonium fluoride gave PhCHDS02F132. Experiments with Et3NH + Cl and a mixture of the fluoride and chloride salts suggested that Cl was also capable of trapping the sulfene, but that the fluoride was more reactive toward sulfene by a factor of 4.6. 

Hydrolysis of the fluoro thiopyrophosphite produces difluorophosphinothious and difluorophosphi-nous acids, both of which rapidly isomerise to the tetrahedral forms (9.540). Similar reactions occur with alcohols (9.541). In aqueous media, reaction with silica glass takes place, but with phosphoric add under anhydrous conditions at low temperatures, OP(OPF2)3 is obtainable as a clear liquid (9.542) [33]. 

The best known, and most widely used sulphydryl protecting group is the benzyl group. Benzylation takes place by reacting benzyl chloride in the presence of base with the thiol in aqueous or non-aqueous media (reaction 4 R = H) > . The reaction could take place also with the sodium... 

HNL catalysis in aqueous medium. Reaction in aqueous solution is performed with an appropriate acidic component and alkali cyanide for in situ development of the required HCN. The following procedure is a typical example194. ... 

In a second attempt to extend the scope of Lewis-acid catalysis of Diels-Alder reactions in water, we have used the Mannich reaction to convert a ketone-activated monodentate dienophile into a potentially chelating p-amino ketone. The Mannich reaction seemed ideally suited for the purpose of introducing a second coordination site on a temporary basis. This reaction adds a strongly Lewis-basic amino functionality on a position p to the ketone. Moreover, the Mannich reaction is usually a reversible process, which should allow removal of the auxiliary after the reaction. Furthermore, the reaction is compatible with the use of an aqueous medium. Some Mannich reactions have even been reported to benefit from the use of water ". Finally, Lewis-acid catalysis of Mannich-type reactions in mixtures of organic solvents and water has been reported ". Hence, if both addition of the auxiliary and the subsequent Diels-Alder reaction benefit from Lewis-acid catalysis, the possibility arises of merging these steps into a one-pot procedure. 

First of all, given the well recognised promoting effects of Lewis-acids and of aqueous solvents on Diels-Alder reactions, we wanted to know if these two effects could be combined. If this would be possible, dramatic improvements of rate and endo-exo selectivity were envisaged Studies on the Diels-Alder reaction of a dienophile, specifically designed for this purpose are described in Chapter 2. It is demonstrated that Lewis-acid catalysis in an aqueous medium is indeed feasible and, as anticipated, can result in impressive enhancements of both rate and endo-exo selectivity. However, the influences of the Lewis-acid catalyst and the aqueous medium are not fully additive. It seems as if water diminishes the catalytic potential of Lewis acids just as coordination of a Lewis acid diminishes the beneficial effects of water. Still, overall, the rate of the catalysed reaction... 

As an application of this nucleophilic reactivity, 2-aminothiazole was used to partially convert into amide the polymer obtained from acrylic acid, benzene, and acetic anhydride (271). An aqueous medium is reported to favor the reaction between acetic anhydride and 2-aminothiazole (272). 

Attack on the electrophilic C-2 may occur as in the 2-aminothiazoles series, which probably explains the rearrangements observed in acidic medium (121, 711, 712, 723, 724), in aqueous medium with NaOAc (725), or with aqueous NaHCOj (725) (Scheme 232). That the initial attack probably involves the C-2 atom is substantiated by the fact that this rearrangement occurs under extremely mild conditions for 2-iinino-3-substituted-5-nitro-4-thiazolines (725). As the whole mechanism proposed (see p. 92) is reversible, when imino derivatives are submitted to such rearrangement conditions the rearrangement is expected to occur faster if steric interaction between 3- and 4-substituents exists in the 2-imino isomer. Another reaction may occur in acidic medium phenylimino-2-bipheny]-3,4-4-thiazoline hydrolyzed with hydrochloric acid gives the corresponding 4-thiazoline-2-one and aniline (717). 

The reaction is carried out at low temperature in aqueous medium and then allowed to stand overnight (221). Ammonium thiocarbamate is prepared from a cold saturated solution of ammonium thiocyanate, which is gradually added to dilute sulfuric acid at 25°C. The liberated carbonyl sulfide is passed into a saturated solution of alcoholic ammonia at about 10°C (221). The fairly low yield indicates that the reaction has not been greatly developed. 

Salts are made by reaction of acryhc acid with an appropriate base in aqueous medium. They can serve as monomers and comonomers in water-soluble or water-dispersible polymers for floor pohshes and flocculants. 

Acetals andKetals. Acetals of 1,3-diols are prepared by refluxing the diol with the aldehyde in the presence of an acid catalyst, even in an aqueous medium. The corresponding ketals are more difficult to prepare in aqueous solution, but cycHc ketals of neopentyl glycol, eg, 2-butyl-2-ethyl-5,5-dimethyl-l,3-dioxane (3), can be prepared if the water of reaction is removed azeotropicaHy (34). 

The (A/-alkylated) lactam of 8-aminonaphthalenecarboxylic acid (47) also is a valuable dye iatemiediate, eg, for cyclometbine-type dyes used for dyeiag polyacrylonitrile fibers and other synthetics. 1,8-Naphtholactams are prepared in high yield and purity by the reaction of naphtholactones with RNH2 (R = H, Cl—4 alkyl, cycloalkyl, or optionally substituted aryl) in aqueous medium, usually in the presence of bisulfite at 150°C over a period of 15 h (143). 

Ethyleneurea Resins. One of the most widely used resins during the 1950s and 1960s was based on dimethylolethyleneurea [136-84-5] (l,3-bis(hydroxymethyl)-2-imidazohdinone) commonly known as ethyleneurea resin. This resin [28906-87-8] is most convenientiy prepared from urea, ethylenediamine, and formaldehyde. 2-Imidazohdinone [120-93-4] (ethyleneurea) is first prepared by the reaction of excess ethylenediamine [107-15-3] wiih. urea (38) in an aqueous medium at about 116°C. 

Some companies have used the Merseburg process to manufacture ammonium sulfate from gypsum, but the process is only economically attractive where sulfur is unavailable or very expensive (32), and is thus not used in the United States. Ammonium carbonate, formed by the reaction of ammonia and carbon dioxide in an aqueous medium, reacts with suspended, finely ground gypsum. Insoluble calcium carbonate and an ammonium sulfate solution are formed. 

Manufacture. The majority of boric acid is produced by the reaction of inorganic borates with sulfuric acid in an aqueous medium. Sodium borates are the principal raw material in the United States. European manufacturers have generally used partially refined calcium borates, mainly colemanite from Turkey. Turkey uses both colemanite and tincal to make boric acid. 

With Unsaturated Compounds. The reaction of unsaturated organic compounds with carbon monoxide and molecules containing an active hydrogen atom leads to a variety of interesting organic products. The hydroformylation reaction is the most important member of this class of reactions. When the hydroformylation reaction of ethylene takes place in an aqueous medium, diethyl ketone [96-22-0] is obtained as the principal product instead of propionaldehyde [123-38-6] (59). Ethylene, carbon monoxide, and water also yield propionic acid [79-09-4] under mild conditions (448—468 K and 3—7 MPa or 30—70 atm) using cobalt or rhodium catalysts containing bromide or iodide (60,61). 

Additions. The addition reactions of ammonia and amines to the cyanamide nitrile group have been thoroughly studied (15). For optimum conditions, the reaction should be carried out ia an aqueous medium at about 140°C. Gradual addition of the cyanamide to the amine salt minimises dimerization. 

The reaction of substituted chloronitrobenzenes with arylamines to form substituted diphenyl amines is typified by 4-rutrodiphenylamine-2-sulfoiiic acid where 4-chloronitrobenzene-3-sulfonic acid (PN salt) is condensed with aniline ia an aqueous medium at 120°C and 200 kPa (2 atm) ia the presence of alkaline buffer at low pH to avoid the competing hydrolysis of the PN salt. 

Laurylmethylamine has been prepared by the reaction of lauryl alcohol with methylamine under pressure in the presence of catalysts at high temperature, by heating lauryl chloride with methylamine in alcoholic or aqueous medium under pressure, and by the reaction of lauryl halides with aqueous methylamine. Cetylmethylamine has been prepared by the catalytic debenzyla-tion of benzylcetylmethylamine. ... 

The reaction may also be carried out in aqueous medium with an increase in the time of reaction to 4 hours. By this method the submitters obtained a 78% yield on a large-scale run. When only a single run is to be made, this procedure may be preferred as a matter of economy. 

Reaction times can be shonened and yields improved through the use of high pressure [40] (equation 28) Reactions may also be conducted in aqueous medium under ultraviolet irradiation [41] (equation 29)... 

Unlike 1,2-diaminoethane, 1,2-phenylenediamine does not add to 1-dialky-laminobut-l-en-3-ynes in the presence of sulfuric acid (84DIS). An attempt to carry out the reaction in an aqueous medium under the conditions of hydroxyl-amine addition resulted in the isolation of 4-dialkylaminobut-3-en-2-one (84DIS). 

Since in an aqueous medium the cyclization-completing stage involves the reaction of a cationoid intermediate with a binucleophile Y such as YNH2 (81UK1252), the end product structure is largely determined by the relative activity of C-1 and C-3 electrophilic centers in this intermediate. 

An important reaction in the chemistry of naphthalenes is the Bucherer reaction,i.e. the conversion of naphthols 1 to naphthylamines 2 as well as the reverse reaction. The reaction is carried out in aqueous medium in the presence of catalytic amounts of a sulfite or bisulfite. Apart from very few exceptions it does not apply to benzene derivatives, which limits the scope of that reaction. 

Another group of uniform latex particles were prepared by the dispersion polymerization of acrolein in an aqueous medium by Margel and coworkers [96], A typical polymerization was conducted in the aqueous alkaline medium having a pH of 10.5, which was obtained by the aqueous NaOH solution. Polyglutaraldehyde-NaHS03 conjugate was synthesized by the reaction of... 

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