Action of acids

An apiofuranosyl-apiose, apiobiose, is released on mild, acid hydrolysis of the apiogalacturonan from Lemna minor.15 

Terminal 3,6-dideoxyhexoses that occur in lipopolysaccharides from Salmonella and Yersinia (Pasteurella) species7 could be hydrolyzed off with a high degree of selectivity. They may, therefore, be located by methylation analysis of the original lipopolysaccharide and of a partially hydrolyzed sample. Thus, for the Salmonella typhi-murium 395 MS lipopolysaccharide, composed18 of oligosaccharide 

Similarly, methylation analysis of a partially hydrolyzed sample of the Klebsiella type 38 capsular polysaccharide, composed of pentasaccharide repeating units (5), revealed that the terminal 3-deoxy-L-g/ycero-pentulosylonic acid group (6) was located at 0-3 of a D-galac-tosyl residue (7), as the 6-O-methyl-D-galactose in the methylation 

The polysaccharide component of a lipopolysaccharide can be separated from the lipid component by selective hydrolysis of the glyco-sidic linkages of the 3-deoxy-D-manno-octulosonic acid residues connecting these two components. The conditions for the hydrolysis are mild, namely, 0.1 M acetic acid for 1.5 h at 100° (Ref. 18). Similar conditions, namely, M formic acid for 1 h at 100° or 0.05 M hydrogen chloride in methanol for 1 h at 85°, were used to split off the sialic acid residues from gangliosides.19,20 

Wolfrom and Rice hydrolyzed heparin in the presence of bromine in order to convert the uronic acids released into aldaric acids.24 The same method, oxidative hydrolysis, was used by Rees and coworkers in order to protect liberated 3,6-anhydrohexose residues. The 

Treatment with mineral acid of the insoluble lead complex of D-glucosone regenerates the free sugar.3 38 

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Occurs in coal tar, in various plants and in faeces, being formed by the action of the intestinal bacteria on tryptophan. It can be prepared by the action of acid on the phenyl-hydrazone of pyruvic acid to give indole-2-carboxylate which can be decarboxylated to indole. 

These two gases can readily be prepared by the action of acids on selenides and tellurides respectively, the reactions being analogous to that for the preparation of hydrogen sulphide. 

Another procedure for obtaining a-aminoketones is by reduction of a-nitrosoketones in the presence of the required carboxylic acid. Acylaminoketones are prepared either by reacting acids with the chlorhydrate of a-aminoketones according to the method of Pictet and Gauss (41) or by the action of acid anhydrides upon a-amino acids (550). 

Tetradifon [116-29-0], 2,4,5,4 -tetrachlorodiphenyl sulfone (141), is a crystalline soHd (mp 148°C). It is soluble in water to 200 mg/L. Tetradifon is stable to the action of acid and alkaUes, light and temperature, and has a very prolonged residual action. It is active against all stages of mites and has an oral... 

The change of mechanism with tertiary alkyl esters is valuable in synthetic methodology because it permits certain esters to be hydrolyzed very selectively. The usual situation involves the use of t-butyl esters, which can be cleaved to carboxylic acids by action of acids such as p-toluenesulfonic acid or trifluoroacetic acid under anhydrous conditions where other esters are stable. 

Z-Ecgonine, CgHigOgN. HjO. This substance was first obtained I Lossen as the final basic hydrolytic product of the action of acids c cocaine, and is obtainable in like manner from several of the alkaloii occurring with cocaine (see above). It crystallises from dry alcohol i monoclinic prisms, m.p. 198° (dec.), 205° (dry), [a]n — 45-4°, is soluble i water, sparingly so in alcohol, insoluble in most organic liquid Eegonine forms Salts with bases and acids the hydrochloride crystallis... 

This substance under the action of alkali passed into anhydrodihydro-protopine A, C20H19O4N, m.p. 120° (V), the amine oxide (VI) of which rearranges into protopine by the action of acids. 

The last isomer, the so-called aldotripiperideine (185), is obtained by the action of acid catalysts on a-tripiperideine at its boiling point (298,299), or in aqueous solution at pH 9.2 and 100°C. Further aldol reaction between tetrahydroanabasine and A -piperideine obviously occurs. Hydrogenolysis of this compound gives dihydroaldotripiperideine (186) which is convertible into matridine (187), a reduction product of the alkaloid matrine. 

CO2 ( fixed air ), prepared by Joseph Black (aged 24-26), was the first gas other than air to be characterized (i) chalk when heated lost weight and evolved CO2 (genesis of quantitative gravimetric analysis), and (ii) action of acids on carbonates liberates CO2. 

CO2 can be readily obtained in small amounts by the action of acids on carbonates. On an industrial scale the main source Is as a byproduct of the synthetic ammonia process in which the H2 required is generated either by the catalytic reaction (a) or by the water-gas shift reaction (b) ... 

If no hydrogen atom is available in the position next to the nitrogen sextet, an alkyl group shifts. In the action of acid on 2-ferf-butyloxaziranc a methyl shift occurs [Eq, (16)]. Formaldehyde... 

It was recently shown that the formation of a Schiff s base is the first step of the reaction between 3-aminopropan-l-ol and an aldehyde. The action of acid chlorides, such as tosyl chloride, on the SchifTs base forms the W-acyl derivative of tetrahydro-1,3-oxazine. 

Isopulegol, Cj Hj O, does not appear to exist in essential oils, but it results from the action of acids on citronellal. The last-named body, for example, when boiled with acetic anhydride yields isopulegyl acetate, from which the alcohol is obtained by hydrolysis. 

Saure-wirkung,/. action of acids, -zahl,/. acid number, -zufuhr,/. addition of acid. Saurung,/. S uerung. sauseln, t.i. rustle murmur lisp hum. sausen, v.i. rush, whiz, whistle, hum. 

From intermediate 43, the path to monensin would seemingly be straightforward. A significant task which would remain would be the construction of the l,6-dioxaspiro[4.5]decane substructure of monensin. You will note that the oxygen atoms affixed to carbons 5 and 12 in 43 reside in proximity to the ketone carbonyl at C-9. In such a favorable setting, it is conceivable that the action of acid on 43 could induce cleavage of both triethylsilyl ethers to give a keto triol which could then participate in a spontaneous, thermodynamically controlled spiroketalization reaction. Saponification of the C-l methyl ester would then complete the synthesis of monensin. 

A mixture of hydrochloric and nitric acids (3 1 by volume) known as aqua regia is a very potent solvent largely due to its oxidising character, and the addition of oxidants such as bromine or hydrogen peroxide frequently increases the solvent action of acids. 

Compounds which are rather unstable. Typical members of this class are 2-furaidehyde, 2-furfuryl alcohol and 2-alkyl furans, the latter being more resistant than the former. The action of acids or oxygen on these derivatives produces appreciable resinification, but, if properly purified and stored in vacuo, they are indefinitely stable25 16s. ... 

Preparation. The early history of the prepn of K perchlorate by the action of acids on K chlorate is reviewed in Ref 3. These authors found that treatment of 2—5g of K chlorate with 50ml of coned sulfuric ac gave an 11 % yield of K perchlorate. The sulfuric ac must be added slowly with cooling to the K chlorate, or expins may result, Similarly, nitric ac gave a yield of 15— 30%, 85% phosphoric ac gave a yield of 15%, and Cr trioxide gave a yield of 12-15%. Org acids failed to yield any perchlorate when heated with K chlorate (Ref 3). It can also be prepu by heating a mixt of solid K chloride with... 

FIGURE 11.19 The state of the carving on Cleopatra s Needle has deteriorated as a result of the action of acid rain tat after 3500 years in the Egyptian desert (b) after a further 00 years in Central Park, New York City. 

For the purposes of this chapter, an arbitrary distinction is made between protonic and thermal activation, wherein protonic activation is caused by the action of acid at room temperature or lower, and thermal activation refers to the use of elevated temperatures with or without the addition of acid. In fact, in both cases, the initial steps in the postulated mechanisms are protonation of the C-2 oxygen atom followed by elimination of the aglycone to yield a ketohexofuranosyl or pyranosyl cation, which is the reactive intermediate in certain circumstances, this might be in equilibrium with the derived glycosyl fluoride. 

Thus, acid-catalyzed hydrolysis of sucrose initially yields D-glucose and a fmctose oxocarbonium ion, which can react with water to form D-fructose and regenerate the H+ catalyst. As a consequence, further acid degradation of sucrose can be described by the action of acids on D-glucose and D-fructose. 

Carboxyl groups Aniline -i- aldose The action of acid causes glucose to be [3]... 

Buildings and statues constructed of marble are sensitive to the destructive action of acid rain. How can the same reactions that destroy marble be used to help reduce the harmful effects of acid rain pollution ... 

An interesting contrast has been observed between the respective actions of acid and alkali on 3,4-anhydro-l,2-isopropylidene-D-tagatose (XXIVo). The anhydro ring of this compound shows considerable resistance to both mineral acids and alkali. Cleavage by sodium meth-... 

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