| 释义 |
Hofmann|ˈhɒfmən|
1. The name of August Wilhelm von Hofmann (1818–92), German chemist, used attrib. and in the possessive to designate dyestuffs discovered and chemical apparatus and procedures devised by him, as Hofmann('s) degradation: (a) the elimination of a carbonyl group from an acid amide when it is heated in a sodium hypohalite solution, giving a primary amine; (b) the pyrolysis of a quaternary ammonium hydroxide to give a tertiary amine and an olefin; Hofmann('s) exhaustive methylation: a method for determining the structure of amino compounds by methylation followed by pyrolysis, the resulting amine being subjected successively to the same procedure until trimethylamine and olefins are obtained; loosely, the Hofmann degradation (sense b); Hofmann('s) method: (a) a method for finding the vapour density of a liquid (see quot. 19022); (b) the preparation of amines by means of the Hofmann degradation of amides; Hofmann('s) reaction: either of the Hofmann degradations; Hofmann('s) rearrangement: the Hofmann degradation of amides; Hofmann('s) rule (see quot. 1954); Hofmann('s) violet (also Violet): any of several basic dyes that are salts of ethyl and methyl derivatives of rosaniline and pararosaniline and were formerly used with wool, silk, and mordanted cotton.
1869H. E. Roscoe Lessons Elem. Chem. (new ed.) xxxix. 385 Triethylrosaniline, C20H16(C2H5)3N3, is manufactured for its splendid colour, and is known as Hofmann's violet. 1876Encycl. Brit. V. 548/1 (caption) Hofmann's Vapour-Density Apparatus. Ibid., Gay-Lussac and Hofmann's Methods. 1902Jrnl. Chem. Soc. LXXXII. ii. 663 Sodium hypochlorite is a more valuable reagent than the hypobromite in Hofmann's reaction. 1902J. B. Cohen Theoret. Org. Chem. iii. 30 Victor Meyer's method and Hofmann's method consist in ascertaining the volume occupied by a given weight of the vaporised substance. Ibid. xiv. 195 If a primary amine is treated by Hofmann's method with an alkyl iodide in which the alkyl group is different from that present in the amine, a mixed amine is formed. 1902Encycl. Brit. XXVII. 337/2 The basis of these methods consists in causing a swelling of the cell⁓wall..and subsequent staining with Hoffmann's blue. 1905Cain & Thorpe Synthetic Dyestuffs xiv. 90 Hofmann's violet was the first violet dyestuff of this [rosaniline] series prepared, and is now merely of historical interest. 1910Chem. Abstr. IV. 583 (heading) Acid properties of halogen amides. Hofmann's rearrangement. 1938L. Small in H. Gilman Org. Chem. II. xii. 1024 The most generally applicable method for ascertaining structure is exhaustive methylation, also known as the Hofmann degradation. 1938Thorpe's Dict. Appl. Chem. (ed. 4) II. 375/1 An important reaction of carboxylic acids is their conversion to amines by the Hofmann degradation, whereby the amide is treated with bromine and alkali. 1938G. H. Richter Textbk. Org. Chem. xiv. 239 (heading) Hofmann's exhaustive methylation. Ibid. 241 The decomposition of these substances on heating to a high temperature has already been indicated in the Hofmann exhaustive methylation procedure. 1949J. R. Partington Adv. Treat. Physical Chem. I. vii. 760 In Hofmann's method, a uniform glass tube about 1 m. long..is supported in a glass jacket through which the vapour of a liquid, boiling in a separate vessel, is passed. Ibid. 761 A modified Hofmann apparatus for accurate vapour-density determinations. 1950L. F. & M. Fieser Org. Chem. (ed. 2) xxxv. 865 The correct structure of the lobelia alkaloids..was first deduced from the result of Hofmann degradation of the quaternary hydroxide. 1951E. D. Hughes in E. H. Rodd Chem. Carbon Compounds Ia. 183 The Hofmann rule refers to the preferential formation of that ethylene which bears the smallest number of alkyl groups. 1952K. Venkataraman Chem. Synthetic Dyes I. i. 3 In 1866 Bardy oxidized a mixture of mono- and dimethylanilines to Methyl Violet, which soon eliminated the Hofmann Violets. 1954Van Nostrand Chem. Dict. 356/2 Hofmann rule, in the decomposition of a quaternary ammonium hydroxide containing different primary alkyl radicals, the products are such that the ethylene formed will contain the least number of alkyl substituents. 1968R. O. C. Norman Princ. Org. Synthesis xiv. 446 (heading) Hofmann rearrangement.
2. The name of Georg von Hofmann-Wellenhof (d. c 1890), Austrian bacteriologist, used attrib. and in the possessive in Hofmann('s) bacillus, a non-pathogenic bacillus similar to the diphtheria bacillus and common in the nose and throat; variously known as Corynebacterium pseudodiphtheriticum, C. hofmanni, etc.
[1891Johns Hopkins Hosp. Bull. II. 143/2 Kolisko and Paltauf..were able to find the pseudo-diphtheritic bacillus of von Hoffmann only very rarely.] 1897Jrnl. Path. & Bacteriol. IV. 190 The cases affected with Hofmann's bacillus unassociated with diphtheria bacilli, which have come under my notice, have always recovered. 1897Trans. Brit. Inst. Prev. Med. 12 Peters..does not seem to have noticed any difference of growth of the Klebs-Löffler and von Hoffmann bacilli on alkaline potato. 1959F. S. Stewart Bigger's Handbk. Bacteriol. (ed. 7) xviii. 307 C. pseudodiphtheriticum (Hofmann's bacillus)..is often present in the nose and less frequently in the throat. |