Ortho carbonic acid

The hypothetical replacement of hydrogen by hydroxyl in silane, or in an alkyl or aiyl silane, results in a series of silanols, formally analogous with the alcohol, vicinal glycol, hydrated carboxylic acid, and ortho-carbonic acid series of carbon chemistry. The silanols are in many ways both the most interesting and the most important silicone intermediates. 

It is, however, sometimes possible to prepare organic derivatives of the completely hydroxylated (often termed ortho- ) acids thus although the aqueous solution of carbon dioxide appears to contain no other acid than an unstable one of the formula CO(OH)2, ethyl ortho-carbonate, C(OEt)i, is known, corresponding with the hypothetical ortho-carbonic acid, C(OH)i. 

The 13C chemical shifts of the parent compound were assigned by comparison with the spectrum of cinnamic acid (see Section 4.11.2) and from the knowledge that for benzenoid methine carbons introduction of an acyloxy function into the benzene ring causes small shifts of the meta carbons, and shifts the signals of the para carbons to higher field, while the ortho carbons become even more shielded (Fig. 5.16) [635]. 

The optical isomers of DOM have been prepared in two ways. The racemic base has been resolved as the ortho-nitrotartranilic acid salt by recrystallization from EtOH. The (+) acid provides the (+) or S isomer of DOM preferentially. Also, the above-mentioned l-(2,5-dimethoxy-4-methylphenyl)-2-propanone can be reductively aminated with optically active alpha-methyl benzylamine with Raney Nickel. This amine is isolated and purified by recrystallization of the hydrochloride salt. When optically pure, the benzyl group was removed by hydrogenolysis with palladium on carbon. The mp of either of the optical isomers, as the hydrochloride salts, was 204-205 °C. 

Degradation Products from the Radiolysis of HDEHP Systems. The main radiolytic degradation products are in the organic phase, mono(2-ethylhexyl) phosphoric acid (H2MEHP), 2-ethylhexanol, and polymeric species, but also a certain amount of ortho phosphoric acid (H3P04) was detected in the aqueous phase. The nature of the short compounds identified in the gas fraction was classical H2, unsaturated and saturated hydrocarbons (from 1 to 4 carbons), 02, and N2 (10, 74, 158-160, 164). 

Many examples are known in which multiple components are brought together about a metal ion to form macrocyclic complexes. Typical examples include the formation of meso-tetraphenylporphyrin (6.21) from benzaldehyde and pyrrole (Fig. 6-20, [4+4]), or phthalocyanine (6.6) from phthalonitrile (Fig. 6-21). The formation of the tetraphenyl-porphyrin is catalysed by a range of Lewis acids, and the facile preparation from aldehydes and pyrroles has obvious implications for the bioevolution of porphyrin pigments. Virtually any benzene derivative with ortho carbon-bearing substituents can be converted to a phthalocyanine complex on heating with a metal or metal salt in the presence of ammonia or some other nitrogen source. 

Fifty grams of calcium carbonate (0.5 mol), 110 g. of 89% orthophosphoric acid (1.0 mol), and 200 ml. of 60% ortho-phosphoric acid (the liquor from the crystallization step in an earlier rim is suitable) are kneaded in a mortar until the" evolution of carbon dioxide has stopped. The mixture is added to 250 ml. of 60% orthophosphoric acid. The resulting slurry is heated until the solid components dissolve and, if necessary, is filtered with suction through a funnel equipped with a sinte ed-glass disk. In order to obtain large crystals of the product, the clear solution must be cooled very slowly to 0°. The crystalline product is filtered, washed seven or eight times with 70-ml. portions of... 

Aryl boronates possessing a Michael acceptor at the ortho-carbon underwent tandem cyclization with strained alkenes such as norbornene981,984 and alkynes977 (Equation (219)). The addition of phenylboronic acid to norbornene... 

Other acyl alkyl esters have been utilized only sporadically. Makita et al. [241] analysed N-isobutyloxycarbonyl methyl esters of protein amino acids. During the first step of the preparation, the amino group reacts with isobutyl chloroformate according to Scheme 5.21. The reaction is accomplished in 10 min in an aqueous medium in the presence of sodium carbonate at room temperature. Excess of the reagent is extracted with diethyl ether and the reaction mixture is saturated with NaCl, acidified with ortho-phosphoric acid to pH 1—2 and extracted with diethyl ether. Methanol is added to the ethereal extract and the carboxyl group is esterified with diazomethane at room temperature for 5 min, The solvent is removed under a stream of nitrogen at 50°C and the residue is dissolved in ethyl acetate. Arg does not provide a volatile derivative when sub-... 

Cupric orthophosphate, Cu3(P04)2,8H20.—The orthophosphate is prepared by the interaction of disodium hydrogen phosphate and excess of cupric sulphate,6 or by heating an aqueous solution of ortho-phosphoric acid with cupric carbonate at 70° C.7 It is a blue, crystalline powder, almost insoluble in water. 

Other carboxylic acid derivatives, for example ortho esters, ortho carbonates,or hy-drazono esters.are obtained via the corresponding acid chloride. Anhydrides are formed by dehydration of carboxylic acids with phosphorus peiitoxide. ... 

There is an alternative mechanism for halide replacement, following the sequence of nucleophile addition, protonation, and elimination of HX. In this pathway, the addition of the nucleophile need not be at the ipso position it can be ortho to halide leading to cine substitution or it can be at the meta or para positions, leading to tele substitution. The processes depend on the formation of the cyclohexadienyl anion intermediates in a favorable equilibrium (carbon nucleophiles from carbon acids with P a > 22 or so), protonation (which can occur at low temperature with even weak acids such as acetic acid), and hydrogen shifts in the proposed diene-chromium intermediates. Hydrogen shifts lead to an isomer that allows elimination of HX and regeneration of an arene chromium complex, now with the carbanion unit indirectly substituted for X (Scheme 40). ... 

The formation of the phenoxide anion enhances the reactivity of the ortho and para positions of the aromatic ring towards electrophilic reagents. The reaction of the phenoxide anion with carbon dioxide at 130 °C leads to ortho carboxylation (the Kolbe reactior. Thus phenol gives salicylic acid (4.4), the acetate of which is aspirin. The reaction is reversible and ortho phenolic acids undergo decarboxylation on heating. 

The reagents used for the completion of the purine heterocycle are essentially the same as those used for the Traubc synthesis. The purine ring is formed by condensation with derivatives of formic acid or other carboxylic acids. Alternatively, formylation of the amino group is accomplished by a mixture of formic acid and acetic anhydride followed by cyclization. Alkyl esters or trialkyl ortho esters are also versatile synthons for ring closure. Moreover, heating in formamide or cyclization with urea or thiourea provides a satisfactory route. Condensations with isothiocyanates show unusual versatility leading to 2-sulfanylpurin-6-ols. From carbonic acid derivatives, cyclization is reported with chlorocarbonic esters, diethyl carbonate or carbon disulfide. 

At temperatures around 200°, a-hydroxyacetates are transformed to oxiranes via a tautomeric ortho-monoester with neighboring-group participation. By the action of heat. CO2 is split off the carbonic acid esters of 1,2-diols and oxiranes are formed. Disecondary or ditertiary 1,2-diols react with diaryldialkoxysulfurane 66 by antiperiplanar intramolecular nucloephilic displacement via a (3-hydroxy-alkoxysulfonium ion intermediate 67 (Eq. 56). ... 

Naphthalene as such has several important uses. Its most common use is as a germicide or insecticide against the attacks of the moth miller larvae in the form of what is known as moth-balls. A more important use is as an enricher or carburetter of water gas for illuminating purposes. As it contains a large amount of carbon it burns with a very luminous flame and thus makes more luminous a weakly illuminating gas. The most important uses of all, however, are as a source of ortho-phthalic acid and in yielding derivatives which are used as dyes. 

From Phenyl Vinyl Acetic Acid.—A second synthesis very closely analogous to the preceding is from phenyl vinyl acetic acid (p. 700), which has the constitution CeHs—CH = CH—CH2—COOH. When this is heated it loses water and yields a hydroxy naphthalene or naph-thol in which the hydroxyl is linked to the carbon next to the ortho carbon of the ring. 

When phenyl glycine ortho-caxhoxyMc acid is fused with potassium hydroxide it first loses water yielding an acid, indoi llic acid, and this loses carbon dioxide yielding indoxyl. In indoxyl the hydroxyl group is in the 3-position while in the isomeric oxindole it is in the 2-position. All of these comp>ounds are thus condensed hetero-cyclic compounds of a benzene ring and a pyrrole ring. Indole is the mother substance and the others are hydroxy or ketone derivatives. 

Naphthalene to Anthranilic Acid.—Such a cheap source was found in naphthalene which was converted into anthranilic acid, orthoamino benzoic acid, and this by treatment with chlor acetic acid yields phenyl glycine ortho-carboxylic acid. The complete synthesis is as follows Naphthalene is oxidized to or// o-phthalic acid which then yields phthalic anhydride. This with ammonia, as ammonium carbonate, yields phthalimide or phthalamidic acid. 

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