Amines and formaldehyde

Similarly, aminomethyl sulphides (from amines, formaldehyde and mercaptans) react with organolithium compounds to afford amines (equation 40)n°4H... 

This MCR chemistry began in 1850 when the Strecker reaction S-3CR of ammonia, aldehydes, and hydrogen cyanide was introduced. Since 1912 the Mannich reaction M-3CR of secondary amines, formaldehyde, and (3-protonated ketones is used. 

Three-component aminomethylation from amine, formaldehyde and a compound with an acidic methylene moiety. 

Russian chemists have reported the synthesis of A-alkyl-3,4-dinitropyrroles from the cy-clization of primary amines, formaldehyde and the potassium salt of 2,3,3-trinitropropanol. ... 

It should be noted that although these potential substitutes avoid the use of NTA, the process of synthesis using amine, formaldehyde, and cyanide also leads to trace amounts of NTA being formed that have to be removed for some applications. With NTA reclassification in Europe now official, the use of these new variants in applications where historically NTA has been used is accelerating. 

Triazene formation can be avoided ab initio by using the JV-(sulfomethyl) derivative instead of the free amine and subsequently hydrolysing off the sulfomethyl group 372 these derivatives are easily obtained from the amine, formaldehyde, and sodium hydrogen sulfite 371... 

The reaction between ammonia (or a primary or secondary amine), formaldehyde and phosphorous acid is only one particular case of the Kabachnik-Medved -Fields reaction, consisting of the aminomethylation of a phosphorus species possessing a reactive P(0)H group, and so is of the Mannich type. The involvement of ammonia leads only to 226 and the intermediate aminomethylphosphonic 227 (R = H) and aminobis(methylene)bisphos-phonic acid 228 (R = H) are not isolable although they are detectable by NMR spectroscopy the sequence can be stopped at the earlier stages if a primary or secondary amine is used The use of a,co-diaminoalkanes leads to complexones of type 229 . Ethanolamine affords the related bis(phosphonic acid) 230 and diethanolamine yields 231 under similar conditions acidolysis of the linear compounds brings about their cyclization... 

Aminomethylation of 7-hydroxycoumarin (110) with a secondary amine, formaldehyde, and acidic alumina gave 111 in 62-100% yields within 1.5 min upon irradiation by MW (Scheme 22) (00SC69). 

The Mannich reaction involving the aminomethylation of electron-rich compounds without any solvent in the presence of acidic alumina under MWI gave good to excellent yields (00SC69). Thus, a mixture of 6-hydroxyquinoline (352) with a secondary amine, formaldehyde, and acidic alumina was irradiated 3 times, each time for 30 s and with 5 min intervals to give the aminomethylated products 353 in 46-98% yields (Scheme 71). 

Typical effective organic pickling inhibitors for steel are quinolinethiodide, o- and p-tolylthiourea, propyl sulfide, diamyl amine, formaldehyde, and p-thiocresol. 

Other routes construct the heterocycle in a one-pot reaction (routes B, C). 1-Substituted imidazoles are formed when an aqueous solution of glyoxal is treated with alkyl amine, formaldehyde, and ammonium salt (route B). The reaction proceeds in acidic media [26]. When 2equiv of the primary amine... 

It will be noted that formation of the dipolar species 89 requires two hydroxide ions, so it is not too surprising that the reaction takes a totally different course in dilute base. Here the products are tetramethyl-oxamide (73), bis(dimethylamino)methane (75), cation 76, dimethyl-amine, formaldehyde, and 1 With the exception of the last two, these products were also obtained in the reaction of dication 50 with aqueous sodium peroxide (see section III.B.5), and their formation may be rationahzed in the same manner. The identification of formaldehyde and 1 in this experiment supports Urry and Sheeto s interpretation of the peroxide reaction. Both products were proposed in this scheme, but both were shown to be oxidized rapidly by aqueous sodium peroxide. 

Mannich Reaction. The IV-methylindole can realize nucleophilic addition on an iminium ion under classical Mannich conditions. The iminium ion can be formed by combining a secondary amine, formaldehyde, and some acid. The Mannich adduct can he isolated in 94% yield (eq 11). ... 

In the above reaction one molecular proportion of sodium ethoxide is employed this is Michael s original method for conducting the reaction, which is reversible and particularly so under these conditions, and in certain circumstances may lead to apparently abnormal results. With smaller amounts of sodium alkoxide (1/5 mol or so the so-called catal3rtic method) or in the presence of secondary amines, the equilibrium is usually more on the side of the adduct, and good yields of adducts are frequently obtained. An example of the Michael addition of the latter type is to be found in the formation of ethyl propane-1 1 3 3 tetracarboxylate (II) from formaldehyde and ethyl malonate in the presence of diethylamine. Ethyl methylene-malonate (I) is formed intermediately by the simple Knoevenagel reaction and this Is followed by the Michael addition. Acid hydrolysis of (II) gives glutaric acid (III). 

Carbocations stabilized by functional groups can also effect 3-alkylalion of indoles. From a synthetic point of view the most important are jV.jV-dialkyl-methyleneiminium ions which can be generated under Mannich conditions from formaldehyde and secondary amines[13]. The products, 3-(A/,A-dialkyl-aminornethyl)indoles, are useful synthetic intermediates (see Chapter 12). 

The Mannich reaction can be realized with formaldehyde and secondary amines. 

Other reactions that show preference for the acidic N-3—H group include Mannich aminomethylation by treatment with formaldehyde and an amine (38) to yield compound (8), reaction with ethyleneimine (39) to give (9), and Michael-type additions (40) such as the one with acrylonitrile to give (10) ... 

Primary nitroparaffins react with two moles of formaldehyde and two moles of amines to yield 2-nitro-l,3-propanediamines. With excess formaldehyde, Mannich bases from primary nitroparaffins and primary amines can react further to give nitro-substituted cycHc derivatives, such as tetrahydro-l,3-oxa2iaes or hexahydropyrimidines (38,39). Pyrolysis of salts of Mannich bases, particularly of the boron trifluoride complex (40), yields nitro olefins by loss of the amine moiety. Closely related to the Mannich reaction is the formation of sodium 2-nitrobutane-1-sulfonate [76794-27-9] by warming 1-nitropropane with formaldehyde and sodium sulfite (41). 

Special resoles are obtained with amine catalysts, which affect chemical and physical properties because amine is incorporated into the resin. For example, the reaction of phenol, formaldehyde, and dimethylamine is essentially quantitative (28). 

Alkyl dimethyl and dialkylmethyl tertiary amines are commercially available. These amines are prepared by reductive methylation of primary and secondary amines using formaldehyde and nickel catalysts (1,3,47,48). The asymmetrical tertiary amines are used as reactive intermediates for preparing many commercial products. 

Primary aromatic amines react with aldehydes to form Schiff bases. Schiff bases formed from the reaction of lower aUphatic aldehydes, such as formaldehyde and acetaldehyde, with primary aromatic amines are often unstable and polymerize readily. Aniline reacts with formaldehyde in aqueous acid solutions to yield mixtures of a crystalline trimer of the Schiff base, methylenedianilines, and polymers. Reaction of aniline hydrochloride and formaldehyde also yields polymeric products and under certain conditions, the predominant product is 4,4 -methylenedianiline [101 -77-9] (26), an important intermediate for 4,4 -methylenebis(phenyhsocyanate) [101-68-8], or MDI (see Amines, aromatic amines, l thylenedianiline). 

A wide selection of amino resin compositions is commercially available. They are all alkylated to some extent in order to provide compatibiUty with the other film formers, and formulation stabiUty. They vary not only in the type of amine (melamine, urea, ben2oguanamine, and glycolutil) used, but also in the concentration of combined formaldehyde, and the type and concentration of alkylation alcohol (/ -butanol, isobutyl alcohol, methanol). 

Formaldehyde may react with the active hydrogens on both the urea and amine groups and therefore the polymer is probably highly branched. The amount of formaldehyde (2—4 mol per 1 mol urea), the amount and kind of polyamine (10—15%), and resin concentration are variable and hundreds of patents have been issued throughout the world. Generally, the urea, formaldehyde, polyamine, and water react at 80—100°C. The reaction may be carried out in two steps with an initial methylolation at alkaline pH, followed by condensation to the desired degree at acidic pH, or the entire reaction may be carried out under acidic conditions (63). The product is generally a symp with 25—35% soHds and is stable for up to three months. 

Primary and secondary amines are usually converted to tertiary amines using formaldehyde and hydrogen in the presence of a catalyst (eqs. 5 and 6). This process, known as reductive alkylation (222), is attractive commercially. The desired amines are produced in high yields and without significant by-product formation. Quatemization by reaction of an appropriate alkylating reagent then follows. 

Methylene chloride is one of the more stable of the chlorinated hydrocarbon solvents. Its initial thermal degradation temperature is 120°C in dry air (1). This temperature decreases as the moisture content increases. The reaction produces mainly HCl with trace amounts of phosgene. Decomposition under these conditions can be inhibited by the addition of small quantities (0.0001—1.0%) of phenoHc compounds, eg, phenol, hydroquinone, -cresol, resorcinol, thymol, and 1-naphthol (2). Stabilization may also be effected by the addition of small amounts of amines (3) or a mixture of nitromethane and 1,4-dioxane. The latter diminishes attack on aluminum and inhibits kon-catalyzed reactions of methylene chloride (4). The addition of small amounts of epoxides can also inhibit aluminum reactions catalyzed by iron (5). On prolonged contact with water, methylene chloride hydrolyzes very slowly, forming HCl as the primary product. On prolonged heating with water in a sealed vessel at 140—170°C, methylene chloride yields formaldehyde and hydrochloric acid as shown by the following equation (6). 

Tricholine Citrate Concentrate. This compound [546-63-4] is a clear, faindy yellow to light-green sympy aqueous Hquid containing 65.0 2.0% trich oline citrate. It is usually has a slight amine odor. It should have a pH of 9.0—10.0 and should contain not more than 0.2% trimethyl amine, 0.5% ethylene glycol, 10 ppm of formaldehyde, and 0.1% residue on ignition. Its limit for heavy metals is 20 ppm and it should contain mote than 0.2% chlorides or sulfates. 

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