Carboxylic acid benzene derivatives

On Sulphonyl Chlorides and Sulphonamides.—The conversion of benzenesulphonic acid into its chloride and amide shows that derivatives of sulphonic acids, analogous to those of carboxylic acids, can be obtained. The sulpho-chlorides are much less reactive than are the chlorides of the carboxylic acids benzene sulphochloride, for example, can be dis-stilled in steam almost without decomposition. 

An alternative procedure for reductive decarboxylation without the use of trialkyltin hydrides as hydrogen atom donors has been developed Alkane carboxylic acid esters derived from AT-hydroxypyridine-2-thione decomposed to alkyl radical, which can readily accept a hydrogen atom from t-BuSH (equation 74) to give alkanes. This reaction can be conveniently performed as a one-pot experiment wherein the acid chloride of an alkane carboxylic acid, the sodium salt of thiohydroxamic acid, t-BuSH and 4-dimethyl-aminopyridine (DMAP) in benzene solution are heated to reflux. This procedure works well for COOH groups attached to primary and secondary carbon atoms. Instead of AT-hydroxypyridine-2-thione, one can use other thiohydroxamic acids, viz. iV-hydroxy-AT-methylthiobenzamide, 3-hydroxy-4-methylthiazole-2(3if)-thione (equation 75) and l-iV-hydroxy-3-AT-methylbenzoylenethiourea for decarboxylation reactions. 

Benzoic acid and naphthoic acid are formed by the oxidative carbonylation by use of Pd(OAc)2 in AcOH. t-Bu02H and allyl chloride are used as reoxidants. Addition of phenanthroline gives a favorable effect[360], Furan and thiophene are also carbonylated selectively at the 2-position[361,362]. fndole-3-carboxylic acid is prepared by the carboxylation of 1-acetylindole using Pd(OAc)2 and peroxodisulfate (Na2S208)[362aj. Benzoic acid derivatives are obtained by the reaction of benzene derivatives with sodium palladium mal-onate in refluxing AcOH[363]. 

It IS hard to find a class of compounds in which the common names of its members have influenced organic nomenclature more than carboxylic acids Not only are the common names of carboxylic acids themselves abundant and widely used but the names of many other compounds are derived from them Benzene took its name from benzoic acid and propane from propionic acid not the other way around The name butane comes from butyric acid present m rancid butter The common names of most aldehydes are derived from the common names of carboxylic acids—valeraldehyde from valeric acid for exam pie Many carboxylic acids are better known by common names than by their systematic ones and the framers of the lUPAC rules have taken a liberal view toward accepting these common names as permissible alternatives to the systematic ones Table 19 1 lists both common and systematic names for a number of important carboxylic acids... 

When side chains of two or more different kinds are attached to a cyclic component, only the senior side chain is named by the conjunctive method. The remaining side chains are named as prefixes. Likewise, when there is a choice of cyclic component, the senior is chosen. Benzene derivatives may be named by the conjunctive method only when two or more identical side chains are present. Trivial names for oxo carboxylic acids may be used for the acyclic component. If the cyclic and acyclic components are joined by a double bond, the locants of this bond are placed as superscripts to a Greek capital delta that is inserted between the two names. The locant for the cyclic component precedes that for the acyclic component, e.g., indene-A - -acetic acid. 

Isoquinoline can be reduced quantitatively over platinum in acidic media to a mixture of i j -decahydroisoquinoline [2744-08-3] and /n j -decahydroisoquinoline [2744-09-4] (32). Hydrogenation with platinum oxide in strong acid, but under mild conditions, selectively reduces the benzene ring and leads to a 90% yield of 5,6,7,8-tetrahydroisoquinoline [36556-06-6] (32,33). Sodium hydride, in dipolar aprotic solvents like hexamethylphosphoric triamide, reduces isoquinoline in quantitative yield to the sodium adduct [81045-34-3] (25) (152). The adduct reacts with acid chlorides or anhydrides to give N-acyl derivatives which are converted to 4-substituted 1,2-dihydroisoquinolines. Sodium borohydride and carboxylic acids combine to provide a one-step reduction—alkylation (35). Sodium cyanoborohydride reduces isoquinoline under similar conditions without N-alkylation to give... 

The methyl ester (100, R = CH3), derived from this A-nor acid by treatment with diazomethane, is different from the ester (102) obtained either by Favorskii rearrangement of 2a-bromo-5a-cholestan-3-one (101) or by the action of cyanogen azide on 3-methoxy-5a-cholest-2-ene (103) followed by hydrolysis on alumina. The ketene intermediate involved in photolysis of (99) is expected to be hydrated from the less hindered a-side of the molecule to give the 2j -carboxylic acid. The reactions which afford (102) would be expected to afford the 2a-epimer. These configurational assignments are confirmed by deuteriochloroform-benzene solvent shifts in the NMR spectra of esters (100) and (102). ... 

Carboxylic acids and their anhydrides acy late a variety of benzene derivatives, fused ring systems, and heterocyclic compounds. An improved procedure for the preparation of l,4-difluoroanthracene-9,10-dione involves reacting phthalic anhydride and 1,4-difluorobenzene to prepare an intermediate carboxylic acid [35] Intramolecular acylation in polyphosphonc acid completes the synthesis (equahon 24). 

Recently, many investigators have extended the early observations that the ultraviolet spectra of - and y-hydroxypyridines resemble those of their A -methyl (not the 0-methyl) derivatives. This spectral resemblance is found both in aqueous solutions and in solutions of solvents with low dielectric constants, e.g., quinol-4-one in benzene, indicating that these compounds exist predominantly in the oxo form under all conditions. These data are summarized in Table I. In contrast, 4-hydroxyquinoline-3-carboxylic acid has been tentatively concluded to exist in the hydroxy form %- pjTid-2-one-4-carboxylic acid has also been formulated as a hydroxy compound, but this has been disputed. ... 

The first characterized derivative substituted in the benzene rings, namely 105c, arose ftom eleciropolymerized indole-5-carboxylic acid, and could be isolated... 

Hydrazides of vicinal acetylene-substituted derivatives of benzoic and azole carboxylic acids are important intermediate compounds because they can be used for cyclization via both a- and /3-carbon atoms of a multiple bond involving both amine and amide nitrogen atoms (Scheme 131). Besides, the hydrazides of aromatic and heteroaromatic acids are convenient substrates for testing the proposed easy formation of a five-membered ring condensed with a benzene nucleus and the six-membered one condensed with five-membered azoles. 

It is only recently that the chloromethylation reaction, well known in the benzene series, has been extended to isoxazoles. It has been thereby found that this reaction results in 4-chloromethyl derivatives (69), their yield decreasing as follows 5-phenyl > 3,5-dimethyl > 5-methyl > 3-methyl isoxazoles > isoxazole. To prove the position of the chloromethyl group these compounds were oxidized to the known isoxazole-4-carboxylic acids (70). It is especially noteworthy that pyridine and its homologs do not undergo chloromethylation. 

Phenyl-9-(2-propoxycarbonylamino)perhydropyrido[2,l-c][l,4]oxazin-1-one was prepared from methyl 4 phenyl-l-oxoperhydropyrido[2, l-c][l,4]oxazine-9-carboxylate (98MIP12). First, the methyl ester was hydrolyzed into 9-carboxylic acid by heating in 6N HCl, then the carboxylic acid was reacted with (Ph0)2P(0)N3 in benzene in the presence of NEt3 at 22 °C for 45 min, then at reflux for 50 min. After addition of -PrOH the reaction mixture was boiled for 20 h to yield a 9-(iso-propoxycarbonylamino) derivative. 

Benzimidazoles are generally synthesized from ortho-diamino-benzenes and carboxylic acid derivatives. The antihistaminic agent, clemizole (60), for example, can be prepared by first reacting ortho-diaminobenzene (57) with chloroacetic acid to form 2-chloro-methylbenzimidazole (58). Displacement of the halogen with pyro-... 

The result is explained by considering the stacking structure between the quinoline moiety and the benzene ring linked to the carboxylic acid, which gives the cavity size adequate for Li+. (Fig. 3) Several selective host molecules for Li+ such as [13]crown-4 18), [14]crown-4 19), [16]crown-4 20>, or noncyclic polyether amide derivatives 21) also possess trimethylene moiety, and this is an interesting finding from the point of view of molecular design of new host molecules for Li+. 

Treatment of ethyl 2,7-di-/ert-butylthiepin-4-carboxylate (24) with 3-chloroperoxybenzoic acid at — 78 °C results in the benzene derivative 25 only, and no sulfur-oxidized products 80 however, the stable 2,7-di-ter/-butylthiepin (26) can be oxidized with 0-benzyl 00-hydrogen monoper-oxycarbonate at — 78 °C to give the corresponding S-oxide 27, which was monitored by HNMR spectroscopy at — 40°C. At —15 C, sulfoxide 27 was converted, via extrusion of sulfur monoxide, with a half-life of 5.5 hours to the benzene derivative 28.87 The oxidation reaction of 26 with excess of the monoperoxycarbonate did not proceed to the S,S-dioxide, even though the parent thiepin 1,1-dioxide is known to be stable at room temperature.15... 

However, it may be that the acid catalysis mechanism is more complex than that described by Scheme 6-5. Broxton and McLeish (1983) investigated the (ii)-diazo ether of a benzene derivative with a carboxy group in the 2-position. They also observed acid catalysis by added carboxylic acids, but, interestingly enough, the reactivity decreased as the strength of the added acid increased. 

Methyl groups attached to benzene rings can be reacted with oxygen to produce aromatic carboxylic acids. Benzoic acid, the parent aromatic acid, finds wide use as a food preservative and in metal corrosion inhibitors. Aspirin and saccharin are derivatives of benzoic acid. 

In reality all carbon atoms share equally the pool of electrons which constitute the double bonds and benzene resists addition across the double bonds which would otherwise destroy its unique structure and stability. Single or multiple hydrogen atoms can be substituted to form a host of derivatives containing similar functional groups to those above, e.g. saturated and unsaturated aliphatic chains, amino, carboxylic acidic, halogeno, nitro, and sulphonic acid groups as shown in Table 3.6. 

The condensation reactions described above are unique in yet another sense. The conversion of an amine, a basic residue, to a neutral imide occurs with the simultaneous creation of a carboxylic acid nearby. In one synthetic event, an amine acts as the template and is converted into a structure that is the complement of an amine in size, shape and functionality. In this manner the triacid 15 shows high selectivity toward the parent triamine in binding experiments. Complementarity in binding is self-evident. Cyclodextrins for example, provide a hydrophobic inner surface complementary to structures such as benzenes, adamantanes and ferrocenes having appropriate shapes and sizes 12) (cf. 1). Complementary functionality has been harder to arrange in macrocycles the lone pairs of the oxygens of crown ethers and the 7t-surfaces of the cyclo-phanes are relatively inert13). Catalytically useful functionality such as carboxylic acids and their derivatives are available for the first time within these new molecular clefts. 

The analytical data obtained, particularly by the PUMA mass spectrometer on board Vega 1 during the flyby, indicate the presence of a large number of linear and cyclic carbon compounds, such as olefins, alkynes, imines, nitriles, aldehydes and carboxylic acids, but also heterocyclic compounds (pyridines, pyrroles, purines and pyrimidines) and some benzene derivatives no amino acids, alcohols or saturated hydrocarbons are, however, present (Kissel and Krueger, 1987 Krueger and Kissel, 1987). 

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