Benzonitriles formation

The reactions of chlorobenzene and benzaldehyde with ammonia over metal Y zeolites have been studied by a pulse technique. For aniline formation from the reaction of chlorobenzene and ammonia, the transition metal forms of Y zeolites show good activity, but alkali and alkaline earth metal forms do not. For CuY, the main products are aniline and benzene. The order of catalytic activity of the metal ions isCu> Ni > Zn> Cr> Co > Cd > Mn > Mg, Ca, Na 0. This order has no relation to the order of electrostatic potential or ionic radius, but is closely related to the order of electronegativity or ammine complex formation constant of metal cations. For benzonitrile formation from benzaldehyde and ammonia, every cation form of Y zeolite shows high activity. 

C. Note that the chronoamperometric it1/2/CA value is constant throughout the accessible time range. These data indicate that the rate of benzonitrile formation is controlled only by the diffusion rate of /7-chlorobenzonitrile, a... 

Fully conjugated 1,2,3,5-thiatriazoles have been described in the form of the mesoionic aminides 9 <1988ACB63>, as thiatriazolium salts 10 <1990J(P2)1619> and as compounds with hexavalent sulfur 11 <1997CJC1188>. The parent 1,2,3,5-thiatriazoles of type 12 are described as elusive intermediates in the reaction of amidrazones with thionyl chloride leading to benzonitrile formation <2004H01J833>. 

Catalytic activities and selectivities were determined separatdy in a fixed-bed U-tube quartz-glass reactor (8 mm i. d.) under similar conditions. Toluene conversion and benzonitrile formation were followed by on-line GC using a FID detector. The carbon oxides were measured by non dispersive infi-ared photometry. 

A narrow wire (a) heated in the vapor of an organic compound such as benzonitrile causes decomposition of the nitrile and the formation of whiskery growths on the surface of the wire (b). The sizes of the growths are exaggerated for purposes of illustration and are, in fact, very small in relation to the diameter of the wire. 

Attempts have been made to catalyze the arrangement of 3-oxaquadricyclane to oxepins with transition-metal complexes.1 32 1 35 When dimethyl 2,4-dimethyl-3-oxaquadricyclane-l,5-dicarboxylate is treated with bis(benzonitrile)dichloroplatinum(II) or dicarbonylrhodium chloride dimer, an oxepin with a substitution pattern different from that following thermolysis is obtained as the main product. Instead of dimethyl 2,7-dimethyloxepin-4,5-dicarboxylate, the product of the thermal isomerization, dimethyl 2,5-dimethyloxepin-3,4-dicarboxylate (12), is formed due to the cleavage of a C O bond. This transition metal catalyzed cleavage accounts also for the formation of a 6-hydroxyfulvene [(cyclopentadienylidene)methanol] derivative (10-15%) and a substituted phenol (2-6%) as minor products.135 The proportion of reaction products is dependent on solvent, catalyst, and temperature. 

The azuleno[l, 8-rc/]azepine 35 is formed as a byproduct from the reaction of excess benzonitrile with 7-isopropyl-l,4-dimethylazulene (guaiazulene, 34) in the presence of a strong base.111 The mode of formation of this unexpected fully conjugated 14jt system has been discussed. 

The reaction between benzylidenetriphenylphosphorane and benzonitrile has been reinvestigated and the primary product (82) isolated. Stable ylides react similarly with activated nitriles, e.g. cyanogen and trifluoro-acetonitrile, but cyanomethylenetriphenylphosphorane with methyl cyano-formate gave largely the vinyl ether (83), the product of a normal olefin synthesis on the carbonyl of the ester group. 

Unfortunately, appearance energy measnrements become more complicated with larger substrates, where the cations are more prone to rearrangement during ionization. Eor example, numerous attempts have been made to measnre the energy for formation of o-benzyne cation, CgH4+ by using benzonitrile as a precursor (Eq. 5.6). 

The formation of a DPP molecule was first reported in 1974 as a minor product in low yield from the reaction of benzonitrile with ethyl bro-moacetate and zinc. A fascinating study by research chemists at Ciba Geigy into the mechanistic pathways involved in the formation of the molecules led to the development of an efficient one-pot synthetic procedure to yield DPP pigments from readily available starting materials, as illustrated in Scheme 4.10. The reaction involves the treatment of diethyl succinate (1 mol) with an aromatic cyanide (2 mol) in the presence of a strong base. The reaction proceeds through the intermediate 88, which may be isolated and used to synthesise unsymmetrical derivatives. 

As with other diazines, addition of benzonitrile oxide to pyridazines results in the formation of angular-fused tricyclic products C1995T11855, 1996T6421>. 

Compound 384 derived from the reaction of two molecules of benzonitrile oxide (341) with one of BCP (3). Its formation can be explained with the cycloaddition of a second molecule of 341 to the isoxazoline Ml to give the isoxazolidine M5, which undergoes a thermal rearrangement to 384 (Scheme 54). 

Evidence for the formation of thiiren by photoelimination of nitrogen from 1,2,3-thiadiazoles has been described,351 and several thiirens, prepared in this way, have been identified in an argon matrix at 8K.352 Phenylthiazirine (422) appears to be an intermediate in the related transformation of 5-phenyl-l,2,3,4-thiatriazole (423) into benzonitrile sulfide (424),353 and further... 

The synthesis of phthalimidines by dicobalt octacarbonyl-catalyzed carbonylation of Schiff bases was first described by Pritchard78 and the scope of the reaction was evaluated by Murahashi et a/.79 Later Rosenthal et al.80-83 subjected a variety of related compounds to carbonylation, and also achieved a phthalimidine synthesis directly from benzonitrile under the conditions of the oxo process.84 An example illustrating the formation of a phthalimidine is shown in Scheme 49 a comprehensive review of the scope and mechanism of reactions of this type is available.85... 

Hynninen and coworkers <99JCS(PT1)2403> used a similar approach to prepare phytochlorin-C6o diad 38 (Scheme 11). The protocol employed the pyrolysis of the natural chlorophyll a molecule 35, followed by transesterification and demetallation to furnish derivative 36. Subsequent oxidation of 36 with OsCU and NaI04 has allowed the synthesis of the formyl derivative 37, which was further used as precursor of the azomethinic ylide intermediate in the 1,3-DC reaction with Cm leading to the formation of diad 38. Photochemical studies revealed that this diad underwent a fast intramolecular photoinduced electron transfer in polar solvents such a benzonitrile <99JACS9378>. 

In particular, the reactions of electrophilically activated benzonitrile A-oxides with 3-methylenephthalimidines with formation of 2-isoxazolines and oximes and the cycloaddition between alkynyl metal(O) Fischer carbenes and nitrones leading to 4-isoxazolines have been investigated by density functional theory methods <06JOC9319 06JOC6178>. 

Analogously, the mesoionic jV-methyl thiazol-5-ones and l,3-dithiol-4-ones afforded A-methyl-4-pyridones and thiapyran-4-ones when reacting with diphenyl cyclopropenone and its thione261. Benzonitrile oxide apparently gives a 1,3-dipolar cycloaddition to the C=0 group of diphenyl cyclopropenone rationalizing the formation of triphenyl-l,3-oxazin-6-one 41626i ... 

As mentioned earlier, 1,2,4-thiadiazoles are generally quite stable to heat due to the aromatic nature of the ring. Irradiation of 3-phenyl-l,2,4-thiadiazole 11, however, resulted in the formation of benzonitrile in 74% yield <2003JOC4855>. 

Formation of mixtures of the above type, which is common with internal olefins, do not occur with many functionalized alkenes. Thus, tertiary cinnamates and cinnamides undergo cycloadditions with benzonitrile oxides to give the 5-Ph and 4-Ph regioisomers in a 25-30 75-70 ratio. This result is in contrast to that obtained when methyl cinnamate was used as the dipolarophile (177). 1,3-Dipolar cycloaddition of nitrile oxides to ethyl o -hydroxycinnamate proceeds regiose-lectively to afford the corresponding ethyl fra s-3-aryl-4,5-dihydro-5-(2-hydro-xyphenyl)-4-isoxazolecarboxylates 36 (178). Reaction of 4-[( )-(2-ethoxycarbo-nylvinyl)] coumarin with acetonitrile oxide gives 37 (R = Me) and 38 in 73% and 3% yields, respectively, while reaction of the same dipolarophile with 4-methoxy-benzonitrile oxide affords only 37 (R = 4-MeOCr>H4) (85%) (179). 

Nucleophilic additions of titanium nucleophiles to nitriles or isonitriles are relatively rare. Eisch et al. recently reported the formation of three-membered ring titanacycles of type 84 and their reactions with benzonitrile and carbon dioxide, respectively (Scheme 34).119,120... 

Very recently, the formation of azabutadienylosmium complexes through transfer of the isopropenyl group of a phosphine ligand to benzonitriles on a Cp-Os metal complex has been reported (Scheme 79).373... 

Since the hybridization and structure of the nitrile group resemble those of alkynes, titanium carbene complexes react with nitriles in a similar fashion. Titanocene-methylidene generated from titanacyclobutane or dimethyltitanocene reacts with two equivalents of a nitrile to form a 1,3-diazatitanacyclohexadiene 81. Hydrolysis of 81 affords p-ketoena-mines 82 or 4-amino-l-azadienes 83 (Scheme 14.35) [65,78]. The formation of the azati-tanacyclobutene by the reaction of methylidene/zinc halide complex with benzonitrile has also been studied [44]. 

The benzonitrile oxide approach also proved to be relatively successful in the case of quinoxaline 343 <1995T11855> and led to formation of the tricyclic product 344 in modest yield (35%). 

Synthesis of the oxadiazolopyrimidone 358 was accomplished by reaction of the amide 357 with phosphorus pentoxide and methylsulfonic acid in low yield <1994PHA880>. Also, its benzologue 360 could only be obtained in very modest yield <2004TL8741> in the case, reaction of the benzonitrile derivative 359 with acetylhydrazine resulted in formation of the bicyclic product 360. 

The substituent effects on the photochemistry between benzene and secondary aliphatic amines53 were studied. Irradiation of toluene or chlorobenzene with diethylamine results in the formation of mixtures of addition and substitution products (equations 34 and 35). Irradiation of anisole or benzonitrile with diethylamine gives the substitution product 7V,7V-diethylaniline (equations 36 and 37). Irradiation of benzylfluoride with diethylamine results in a side-chain substitution (equation 38). The photoreaction of p-fluorotoluene with diethylamine gives both substitution and reduction products (equation 39). 

Cycloadditions to a cyano group are comparatively rare. The high-temperature reactions of 1,3-dienes, e.g. butadiene, isoprene and 2-chloro-l,3-butadiene, with dicyanogen, propionitrile or benzonitrile result in formation of pyridines (equation 80)70. Sulfonyl cyanides 147, obtained by the action of cyanogen chloride on sodium salts of sulfinic acids, add to dienes to give dihydropyridines 148, which are transformed into pyridines 149 by oxidation (equation 81)71. 

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