Hofmann, Ber., 188 2, 1 5, p. 977), by the partial hydrolysis of the nitriles, by the action of ammonia or ammonium carbonate on acid chlorides or anhydrides, or by heating the.
The secondary and tertiary amides of the types (RCO) 2 NH and (RCO) 3 N may be prepared by heating the primary amides or the nitriles with acids or acid anhydrides to 200° C. Thiamides of the type R.
The acid esters of phenol are best obtained by the action of acid chlorides or anhydrides on phenol or its sodium or potassium salt, or by digesting phenol with an acid in the presence of phosphorus oxychloride (F.
With genuine soaps, however, it suffices to calculate the fatty acids as anhydrides and add to this the amount of alkalis, and estimate the water by difference.
Williamson showed how alcohol and ether were to be regarded as derived from water by substituting one or both hydrogen atoms by the ethyl group; he derived acids and the acid anhydrides from the same type; and from a comparison of many inorganic and the simple organic compounds he concluded that this notion of a " water-type " clarified, in no small measure, the conception of the structure of compounds.
Taking as types hydrogen, hydrochloric acid, water and ammonia, he postulated that all organic compounds were referable to these four forms: the hydrogen type included hydrocarbons, aldehydes and ketones; the hydrochloric acid type, the chlorides, bromides and iodides; the water type, the alcohols, ethers, monobasic acids, acid anhydrides, and the analogous sulphur compounds; and the ammonia type, the amines, acid-amides, and the analogous phosphorus and arsenic compounds.
Considering derivatives primarily concerned with transformations of the hydroxyl group, we may regard our typical acid as a fusion of a radical R CO - (named acetyl, propionyl, butyl, &c., generally according to the name of the hydrocarbon containing the same number of carbon atoms) and a hydroxyl group. By replacing the hydroxyl group by a halogen, acid-haloids result; by the elimination of the elements of water between two molecules, acid-anhydrides, which may be oxidized to acid-peroxides; by replacing the hydroxyl group by the group. SH, thio-acids; by replacing it by the amino group, acid-amides (q.v.); by replacing it by the group - NH NH2, acid-hydrazides.
As a useful preliminary it is convenient to divide heterocyclic ring systems into two leading groups: (I) systems resulting from simple internal dehydration (or similar condensations) of saturated aliphatic compounds - such compounds are: the internal anhydrides or cyclic ethers of the glycols and thioglycols (ethylene oxide, &c.); the cyclic alkyleneimides resulting from the splitting off of ammonia between the amino groups of diaminoparaffins (pyrrolidine, piperazine, &c.); the cyclic esters of oxycarboxylic acids (lactones, lactides); the internal anhydrides of aminocarboxylic acids (lactams, betaines); cyclic derivatives of dicarboxylic acids (anhydrides, imides, alkylen-esters, alkylenamides, &c.).
As before, only true ring nuclei, and not internal anhydrides of aliphatic compounds, will be mentioned.
In 1849 he discovered anhydrous nitric acid (nitrogen pentoxide), a substance interesting as the first obtained of the so-called " anhydrides " of the monobasic acids.
Reissert, Ber., 18 99, 3 2, p. 782), the chief product in this latter reaction being an isoindazolone: // CH2 NHC6H5 /CH2 NH C6H5 /CH2 NC6H5 C6H4 - C6H4 - C6 H4 NH 2 HCI N :NCI N=N The best drawn series of the triazines is the symmetrical or cyanidine series, members of which result from the condensation of acid anhydrides with aromatic amidines (A.
They are neutral to litmus and do not combine with dilute acids or bases; strong bases, such as lime and baryta, yield saccharates, whilst, under certain conditions, acids and acid anhydrides may yield esters.
Chemically they appear to be ether anhydrides of the hexoses, the union being effected by the aldehyde or alcohol groups, and in consequence they are related to the ethers of glucose and other hexoses, i.e.
Phosphorus chlorides give acid chlorides, Rï¿½COï¿½C1, the hydroxyl group being replaced by chlorine, and acid anhydrides, (Rï¿½CO) 2 0, a molecule of water being split off between two carboxyl groups.
Acid anhydrides replace the imino-hydrogen atom by acidyl radicals, and boiling with water converts them into phenols.
On the constitution, of these anhydrides see E.
Those derived from monobasic acids, obtained by the action of acid chlorides or anhydrides on urea, decompose on heating and do not form salts.
They may be regarded as the anhydrides of the alcohols, being formed by elimination of one molecule of water from two molecules of the alcohols; those in which the two hydrocarbon radicals are similar are known as simple ethers, and those in which they are dissimilar as mixed ethers.
KETENES, in chemistry, a group of organic compounds which may be considered as internal anhydrides of acetic acid and its substitution derivatives.
With the anhydrides of dibasic acids it yields fluoresceins (q.v.).
The Benzidine and Semidine Change.-Aromatic hydrazo compounds which contain free para positions are readily converted by the action of acids, acid chlorides and anhydrides into diphenyl derivatives; thus, as mentioned above, hydrazobenzene is converted into benzidine, a small quantity of diphenylin being formed at the same time.
Oxyacids.-Phosphorus forms several oxyacids: hypophosphorous acid, H 3 P0 2, and hypophosphoric acid, H 4 P 2 0 6 or H2P03, of which the anhydrides are unknown; phosphorous acid, H 3 P0 3, derived from P 4 0 5; monoperphosphoric acid, H 3 P0 5; perphosphoric acid, H4P208; and meta-, pyro-, and ortho-phosphoric acids, derived from P4010, for which see Phosphates.