Formaldehyde condensation with aromatic

Batch syntheses comparable to those used for MDA produce 3,3 -dimethy1methy1enedi(cyclohexylamine) marketed under the trade name Laromia C-260. The starting aromatic diamiae, 3,3 -dimethy1methy1enediani1ine [838-88-0] is prepared from o-toluidine [95-53-4] condensation with formaldehyde. Similarly 3,3 -dimethyldicyclohexylaniiae [24066-10-2] may be produced (38) from o-toHdine [119-93-7] derived from o-nitrotoluene [88-72-2]. The resultant isomer mixtures are dependent on reduction conditions as ia MDA hydrogeaatioa. 

Aliphatic and aromatic aldehydes condensed with 2-amino-(62BRP898414), 5-amino- (80AJC1147), or 8-amino-l,2,4-triazolo[l,5-cjpyrimidines (68JOC530) to give the related Schiff bases. Treatment of the 2-amino-5-methyl-l,2,4-triazolo[l,5-c]quinazoline 11 with formaldehyde and piperidine in the presence of acetic acid gave the 2-hydroxymethyl-amino-5-(2-piperidinoethyl) derivative 172. Utilization of aromatic aldehydes and piperidine in this reaction gave the 2-arylideneamino-5-styryl derivatives 173 (68CB2106) (Scheme 67). 

The sulphonated aromatic condensation products form a large and varied group, since formaldehyde will condense with many aromatic compounds [330], including sulphonated arylamines, phenols and aliphatic ketones the range of commercially important products is relatively limited, however. One of the oldest is the condensation product of naphthalene-2-sulphonic acid and formaldehyde (10.99), in which the degree of condensation is thought to... 

Compound 7-ethyl-7-methyl-3-phenyl-2,3,4,9-tetrahydropyrimido[l,2-tf][l,3,5]triazine-6,8-dione 71 <2002JHC663> was prepared by the one-pot condensation reaction of 6-amino-3-cthyl-3-mcthyl-5//-pyndinc-2,4-dionc 70 with aromatic amines and formaldehyde (Equation 3). 

The two key isocyanates that are used in the greatest volumes for polyurethane polymers are toluene diisocyanate (TDl) and methylene diphenyl diisocyanate (MDl). Both isocyanates are produced first by nitration of aromatics (toluene and benzene, respectively), followed by hydrogenation of the nitro aromatics to provide aromatic amines. In the case of MDl, the aniline intermediate is then condensed with formaldehyde to produce methylene dianiline (MDA), which is a mixture of monomeric MDA and an oligomeric form that is typical of aniline/formaldehyde condensation products [2]. The subsequent reaction of phosgene with the aromatic amines provides the isocyanate products. Isocyanates can also be prepared by the reaction of aromatic amines with dimethylcarbonate [3, 4]. This technology has been tested at the industrial pilot scale, but is not believed to be practiced commercially at this time. 

Amine-modified polyamides can be prepared by condensation with formaldehyde and aromatic amines at room temperature the pendant groups are reported to act as active centers for grafting of acrylonitrile, acrylamide, methyl methacrylate and N-vinyl pyrrolidone (152). 

Gronowitz found the Pictet-Spengler reaction a convenient route for the preparation of (259 equation 22) (70AK(32)217). Thiophene-3-carbaldehyde was condensed with nitromethane to give w-nitrovinylthiophene. Reduction of the nitro derivative with LAH afforded the /3-(thienyl)ethylamine. The condensation of this amine with formaldehyde to the corresponding imine followed by cyclization with hydrochloric acid proceeded very smoothly and in high yield. The aromatization was achieved with potassium ferricyanide in an alkaline dioxane-water mixture. 

Reaction XXXIH. (a) Condensation of an Aromatic Carboxylic Acid with Formaldehyde. (Lederer-Manasse).—In the presence of mineral acids formaldehyde condenses to di-phenyl derivatives with aromatic acids in much the same way as with phenols (Reaction XIII.), except that in this case it is in the meta position the condensation takes place. 

Two different classes of chemical reactions are singled out, namely the reactions of addition of formaldehyde to the aromatic ring, which introduce a methylol group as a substituent, and the reactions of condensation, which produce components with higher molecular weight. In the presence of an alkaline catalyst, the reactions of addition are strongly oriented in the -orto and -para positions of the aromatic ring, whereas the reactions of condensation occur both between two substituted positions... 

Even imines formed by in situ condensation of aromatic amines with either acetaldehyde or formaldehyde afforded the desired products. The successful radical addition to these rather unstable and polymerizable imines in aqueous medium may be ascribed to the lack of steric hindrance at the C-atom. 

Cyclization of the 4-phenylhydrazono derivatives of 2-thiazolidinone with formaldehyde or aromatic aldehydes gives 2-phenyl-2,3-dihydro-thiazolo[4,3-c]l,2,4-triazol-5-ones (131) [Eq. (39)] subsequent condensation with aldehydes affords the corresponding 7-arylidene derivatives.171... 

Additionally, formaldehyde may condense with two aromatic units to form another diphenylmethane-type condensed structure (59). These condensation reactions have been well established in lignin model studies (32,300,301]. 

A first group of reactions deals with unsaturated substrates, aromatic derivatives included, giving cyclic products, according to Figs. 44 and 46 of Sec. C.4 this is done by condensation with amino derivatives and one equivalent of formaldehyde or by... 

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