Benzene with formaldehyde

In the present paper we have studied four acid catalyzed reaotions involving carbonyl compounds alkylation of benzene with formaldehyde, esterification of phenylacetic acid, Friedel-Crafts acylation by phenylpropanoyl chloride, and the cross aldolic condensation of acetophenone with benzaldehyde in the presence of three Hp zeolites with different framework Si-to-Al... 

A variety of solid acids has been studied in the alkylation of benzene with formaldehyde to produce diphenylmethane264 [Eq. (5.99)]. Aciplex-Si02 exhibited... 

Calixarenes (from the Latin ca/ x) may be understood as artificial receptor analogues of the natural cyclodextrins (96,97). In its prototypical form they feature a macrocycHc metacyclophane framework bearing protonizable hydroxy groups made from condensation of -substituted phenols with formaldehyde (Fig. 15b). Dependent on the ring size, benzene derivatives are the substrates most commonly included into the calix cavity (98), but other interesting substrates such as C q have also been accommodated (Fig. 8c) (45). 

Platinum-group metals (qv) form complexes with chelating polymers with various 8-mercaptoquinoline [491-33-8] derivatives (83) (see Chelating agents). Hydroxy-substituted quinolines have been incorporated in phenol—formaldehyde resins (84). Stannic chloride catalyzes the condensation of bis(chloromethyl)benzene with quinoline (85). 

Chloromethylation (Blanc-QueletReaction). Benzene reacts with formaldehyde and hydrochloric acid ia the presence of ziac chloride to yield chloromethylbenzene [100-44-7], C HyCl (benzyl chloride) (29), a chemical iatermediate. 

The introduction of a chloromethyl group on aromatic compounds (e.g. benzene 1) by reaction with formaldehyde 2 and gaseous hydrogen chloride in the presence of a catalyst is called the Blanc reaction ... 

There are a number of variations of the Friedel-Crafts reactions that are useful in synthesis. The introduction of chloromethyl substituents is brought about by reaction with formaldehyde in concentrated hydrochloric acid and halide salts, especially zinc chloride.62 The reaction proceeds with benzene and activated derivatives. The reactive electrophile is probably the chloromethylium ion. 

Isomeric l,3-diaza-6-thiaadamantane 6,6-dioxide (232) is prepared by cyclocondensation of 3-benzenesulfonyl-9-thia-3,7-diazabicyclo[3.3.1]nonane-9,9-dioxide (233) with formaldehyde, where 233 is derived from /V-benzene-sulfonyl-2,6-dimethylthiomorpholine (234).2 54... 

The nitroso-group in the p-position has a remarkable influence in making possible the hydrolytic removal of the dimethylamino group from the benzene ring. The reaction is used technically for the preparation of secondary amines. (Trimethylamine is obtained by heating ammonium chloride with formaldehyde.)... 

Photolytic. A photooxidation rate constant of 6 x 10 " cm /molecule-sec at room temperature was reported for the vapor-phase reaction of benzene with OH radicals in air (Atkinson, 1985). The reported rate constant and half-life for the reaction of benzene and OH radicals in the atmosphere are 8.2 x 10 M/sec and 6.8 d, respectively (Mill, 1982). Major photooxidation products in air include nitrobenzene, nitrophenol, phenol, glyoxal, butanedial, formaldehyde, carbon dioxide, and carbon monoxide (Nojima et al., 1975 Finlayson-Pitts and Pitts, 1986). 

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. 

Cyclotriveratrylene/1180-60-5] (34) is a cyclocondensation product of veratrole with formaldehyde. It possesses a stable trigonal crown conformation and forms crystalline inclusion compounds with benzene, chlorobenzene, toluene, thiophene, decalin, chloroform, acetone, carbon disulfide, acetic acid, and butyric acid (101). Their structures consist of columns of cyclotriveratrylene molecules that are not amenable to close packing and provide channels into which the guests are accommodated. A number of modified host structures, derived from prototype (34) have been prepared. The hexaphenol analogue cyclotricatechylene also yields well-defined channel inclusions (101). They involve mosdy polar guests and the structures are held by hydrogen bonding. 

The dioxazepine (lc) was formed when funtumine (Id) was treated with formaldehyde and ethane-1,2-diol in benzene. Under similar conditions, epi-holafebrine (3e) furnished the dioxazepine (3f).5... 

Octaethylporphyrin can also be obtained from 2 by a more conventional approach.3 The a-ester group is removed by saponification and decarboxylation, and the resulting 3,4-diethylpyrrole is condensed in benzene with aqueous formaldehyde in the presence of TsOH with removal of water and then oxidized with air (yield 75%).3... 

Oxazolidines are commonly prepared from /3-amino alcohols and carbonyl compounds (equation 173). The condensation is conveniently conducted in boiling benzene with continuous removal of water. Treatment of 2-aminoethanol with formaldehyde yields the parent compound (67BSF571). An interesting reaction is the formation of the enantiomerically pure oxazolidine (307) from (-)-ephedrine and the alkynic sulfone PhS02C=CMe (79JCS(P1)1430). 

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