Aromatic compounds with ammonia

Reactions of Aromatic Compounds with Ammonia over Y Zeolite... 

Photoamination of a variety of aromatic compounds with ammonia and alkyl-amines under photosensitized electron transfer mediated reaction conditions has been extensively investigated by Yasuda and coworkers (Scheme 70) [320-324]. The photoamination reactions of stilbene derivatives with ammonia have been utilized for the synthesis of a variety of isoquinoline derivatives [324]. The photoamination is initiated by photochemical electron transfer from the arenes to the electron acceptor followed by nucleophilic attack of ammonia or primary amines on the aromatic radical cations (Scheme 70). 

Manufacture of many important amino intermediates used for dyes and other purposes is usually by conversion or replacement of a substituent. For example, as already mentioned, in substituted nitro compounds, the nitro groups may be reduced with iron/hydrochloric acid, hydrogen and catalyst, or zinc in aqueous alkali. Partial reductions can be brought about with sodium sulfide. Amino groups may be introduced by replacing halogens in the aromatic ring. Another approach to amination is by attack on a substituted aromatic compound with ammonia or amines. Thus, for example, direct amination of p-chloronitrobenzene (15a) in the presence of a copper catalyst affords p-nitroaniline (15b) in almost quantitative yield l,4-dichloro-2-nitrobenzene (16) is converted in a similar way to 4-chloro-2-nitroaniline (17). Reactions of ammonia with carboxylic acids or anhydrides are carried out on an industrial scale. 

Wibaut JP (1917) For the formation of aniline from ammonia and benzene at high temperatures and in the presence of contact substances. Berichte 50 541-546 Thomas Cl (1985) Preparation of aromatic amines. Canadian Patent 553,988, 4 Mar 1958 Schmerling L (1960) Preparation of aromatic amines. US Patent 2,948,755, 9 Aug 1960 Squire EN (1975) Synthesis of aromatic amines by reaction of aromatic compounds with ammonia. US Patent 3,919,155, 11 Nov 1975... 

Del Pesco TW (1977) Synthesis of aromatic amines by reaction of aromatic compounds with ammonia. US Patent 4,031,106, 21 Jun 1977... 

One of the most general pyrrole syntheses is the cyclizative condensation of 1,4-dicarbonyl compounds with ammonia, a primary amine or related compound. The mechanistic pattern involves formation of carbinolamine and imine intermediates followed by aromatization. This method is sometimes referred to as the Paal-Knorr pyrrole synthesis (equation 65) (B-77MI30601). Once the dicarbonyl compound is available, the cyclization normally proceeds in good yield, so ease of access to the diketone is of major importance in determining the applicability of this method to specific pyrroles. Pyrrole formation usually takes place on heating the diketone in a solvent such as benzene or toluene with a catalytic amount of acid. An alternative method involves heating the dicarbonyl compound and an amine salt... 

Table 10 gives the partial rate factors for deuterium exchange of aromatic compounds with a KNH2 solution in liquid ammonia (Hall et al., 1955 Shatenshtein and Izrailevich, 1962 Shatenshtein and Ranneva, 1961 Shatenshtein and Vedeneev, 1958a, b Shatenshtein et al., 1960 Yurygina et al., 1960). 

Miller, R. S., Curtin, D. Y., and Paul, I. C. Reactions of molecular crystals with gases. I. Reactions of solid aromatic carboxylic acids and related compounds with ammonia and amines. J. Amer. Chem. Soc. 96, 6329-6334 (1974). 

Hoijtink et al. [27] also developed an alternative method of generating anionic species, which was improved by Szwarc et al. [28]. The technique involves potentiometric titration of aromatic compounds with a standard solution of Na-biphenylide. The extremely negative reduction potential of biphenyl assures that most of the common aromatics can be reduced to at least their respective radical anions. The values of the thermodynamic reduction potentials are generally obtained from the potentiometric titration curve. As all experiments are usually carried out in ethereal solutions, such as tetrahydrofuran (THF) or dimethoxyethane, problems of follow-up processes are less severe. Later, Gross and Schindewolf [29] reported on the potentiometric titration of aromatics using solvated electrons in liquid ammonia. 

For the effect of a trace of iron on the reduction of aromatic compounds with U or Na, ammonia, and an alcohol, see Birch reduction. 

It should, however, be noted that aromatic amino-nitro compounds are often more conveniently prepared by heating a halo-nitro compound with ammonia or an amine (e.g., N,N-dimethy -o- and -p-nitroaniline194) or by partial reduction of a polynitro compound (cf. pp. 463 et seq. and 575). 

What happens if you extend the chain to a third carbon The parent system is called the phenyl-(n)-propylamine, and the parent chain structure, either as the primary amine or as its alpha-methyl counterpart, represents compounds that are inactive as stimulants. The DOM-analogues have been made and are, at least in the rabbit rectal hyperthermia assay, uninteresting. A commercially available fine chemical known as piperonylacetone has been offered as either of two materials. One, correctly called 3,4-methylenedioxyphenylacetone or 3,4-methylenedioxybenzyl methyl ketone, gives rise upon reductive amination to MDA (using ammonia) or MDMA (using methylamine). This is an aromatic compound with a three-carbon... 

Pyridines can be made by condensation reactions of acyclic starting materials such as carbonyl compounds with ammonia. The most general of these methods is the Hantzsch pyridine synthesis. In this reaction, two molecules of a j8-dicarbonyl compound, an aldehyde, and ammonia combine in several steps (Worked Example 25-28) to give a substituted dihydropyridine, which is readily oxidized by nitric acid to the aromatic system. When the j8-dicarbonyl compound is a 3-ketoester, the resulting product is a 3,5-... 

In Summary Pyridines are aromatic but electron poor. The lone pair on nitrogen makes the heterocycle weakly basic. Pyridines are prepared by condensation of a jS-dicarbonyl compound with ammonia and an aldehyde. 

Picrates, Many aromatic hydrocarbons (and other classes of organic compounds) form molecular compounds with picric acid, for example, naphthalene picrate CioHg.CgH2(N02)30H. Some picrates, e.g., anthracene picrate, are so unstable as to be decomposed by many, particularly hydroxylic, solvents they therefore cannot be easily recrystaUised. Their preparation may be accomplished in such non-hydroxylic solvents as chloroform, benzene or ether. The picrates of hydrocarbons can be readily separated into their constituents by warming with dilute ammonia solution and filtering (if the hydrocarbon is a solid) through a moist filter paper. The filtrate contains the picric acid as the ammonium salt, and the hydrocarbon is left on the filter paper. 

Preliminary indication of the presence of a phenol ester may be obtained by heating the compound with soda-lime esters of phenols and also aromatic hydroxy-acids usually give the phenol. (Likewise amides, Imides, nitriles, substituted hydrazines, uretheines, etc. eifiord ammonia.)... 

CoF is used for the replacement of hydrogen with fluorine in halocarbons (5) for fluorination of xylylalkanes, used in vapor-phase soldering fluxes (6) formation of dibutyl decalins (7) fluorination of alkynes (8) synthesis of unsaturated or partially fluorinated compounds (9—11) and conversion of aromatic compounds to perfluorocycHc compounds (see Fluorine compounds, organic). CoF rarely causes polymerization of hydrocarbons. CoF is also used for the conversion of metal oxides to higher valency metal fluorides, eg, in the assay of uranium ore (12). It is also used in the manufacture of nitrogen fluoride, NF, from ammonia (13). 

Iron(III) bromide [10031-26-2], FeBr, is obtained by reaction of iron or inon(II) bromide with bromine at 170—200°C. The material is purified by sublimation ia a bromine atmosphere. The stmcture of inoa(III) bromide is analogous to that of inon(III) chloride. FeBr is less stable thermally than FeCl, as would be expected from the observation that Br is a stronger reductant than CF. Dissociation to inon(II) bromide and bromine is complete at ca 200°C. The hygroscopic, dark red, rhombic crystals of inon(III) bromide are readily soluble ia water, alcohol, ether, and acetic acid and are slightly soluble ia Hquid ammonia. Several hydrated species and a large number of adducts are known. Solutions of inon(III) bromide decompose to inon(II) bromide and bromine on boiling. Iron(III) bromide is used as a catalyst for the bromination of aromatic compounds. 

They show good to excellent resistance to highly aromatic solvents, polar solvents, water and salt solutions, aqueous acids, dilute alkaline solutions, oxidative environments, amines, and methyl alcohol. Care must be taken in choice of proper gum and compound. Hexafluoropropylene-containing polymers are not recommended for use in contact with ammonia, strong caustic (50% sodium hydroxide above 70°C), and certain polar solvents such as methyl ethyl ketone and low molecular weight esters. However, perfluoroelastomers can withstand these fluids. Propylene-containing fluorocarbon polymers can tolerate strong caustic. 

Benzisothiazoles can be prepared by the reaction of aromatic chloro compounds with sulfur and ammonia. Thus, 2,6-dichlorobenzylidene chloride gives 4-chloro-l,2-benzisothiazole (72AHC(14)43), and 2-chlorobenzophenone gives 3-phenyl-l,2-benziso-thiazole (79GEP27 34866). 

Two substituents on two N atoms increase the number of diaziridine structures as compared with oxaziridines, while some limitations as to the nature of substituents on N and C decrease it. Favored starting materials are formaldehyde, aliphatic aldehydes and ketones, together with ammonia and simple aliphatic amines. Aromatic amines do not react. Suitable aminating agents are chloramine, N-chloroalkylamines, hydroxylamine-O-sulfonic acid and their simple alkyl derivatives, but also oxaziridines unsubstituted at nitrogen. Combination of a carbonyl compound, an amine and an aminating agent leads to the standard procedures of diaziridine synthesis. 

The A-ring of the 17-ol (25) derived from equilenin 3-methyl ether is reduced rapidly under Birch reduction conditions, since the 1,4-positions are unsubstituted. The B-ring is reduced at a much slower rate, as is characteristic of aromatic compounds in which 1,4-reduction can occur only if a proton enters an alkylated position. Treatment of (25) with sodium and t-butyl alcohol in ammonia reduces only the A-ring to afford the corresponding 1,4-dihydro compound in over 85% yield.On the other hand,... 

The term Birch reduction was originally applied to the reduction of aromatic compounds by alkali metals and an alcohol in ammonia. In recent years many chemists have used the term to include all metal-ammonia reductions, whether an alcoholic proton source is present or not. The author prefers to use the term Birch reduction to designate any reduction carried out in ammonia with a metal and a proton donor as or more acidic than an alcohol, since Birch customarily used such a proton donor in his extensive pioneering work. The term metal-ammonia reduction is best reserved for reductions in which ammonia is the only proton donor present. This distinction in terminology emphasizes the importance of the acidity of the proton donor in the reduction process. 

Heterocyclic enamines A -pyrroline and A -piperideine are the precursors of compounds containing the pyrrolidine or piperidine rings in the molecule. Such compounds and their N-methylated analogs are believed to originate from arginine and lysine (291) by metabolic conversion. Under cellular conditions the proper reaction with an active methylene compound proceeds via an aldehyde ammonia, which is in equilibrium with other possible tautomeric forms. It is necessary to admit the involvement of the corresponding a-ketoacid (12,292) instead of an enamine. The a-ketoacid constitutes an intermediate state in the degradation of an amino acid to an aldehyde. a-Ketoacids or suitably substituted aromatic compounds may function as components in active methylene reactions (Scheme 17). 

Arynes are intermediates in certain reactions of aromatic compounds, especially in some nucleophilic substitution reactions. They are generated by abstraction of atoms or atomic groups from adjacent positions in the nucleus and react as strong electrophiles and as dienophiles in fast addition reactions. An example of a reaction occurring via an aryne is the amination of o-chlorotoluene (1) with potassium amide in liquid ammonia. According to the mechanism given, the intermediate 3-methylbenzyne (2) is first formed and subsequent addition of ammonia to the triple bond yields o-amino-toluene (3) and m-aminotoluene (4). It was found that partial rearrangement of the ortho to the meta isomer actually occurs. 

The Hantsch pyridine synthesis provides the final step in the preparation of all dihydrop-yridines. This reaction consists in essence in the condensation of an aromatic aldehyde with an excess of an acetoacetate ester and ammonia. Tlie need to produce unsymmetrically subsrituted dihydropyridines led to the development of modifications on the synthesis. (The chirality in unsymmetrical compounds leads to marked enhancement in potency.) Methyl acetoacetate foniis an aldol product (30) with aldehyde 29 conjugate addition of ethyl acetoacetate would complete assembly of the carbon skeleton. Ammonia would provide the heterocyclic atom. Thus, application of this modified reaction affords the mixed diester felodipine 31 [8]. 

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