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▪ I. Schmidt1 Org. Chem.|ʃmɪt|
[The name of Karl Friedrich Schmidt (b. 1887), German chemist, who first employed a reaction of this kind in 1923 (Zeitschr. f. angew. Chem. XXXVI. 511).]
Schmidt('s) reaction: a widely-used synthetic method in which a carbonyl compound is treated with hydrazoic acid in the presence of mineral acid, the product(s) depending on the kind of carbonyl compound used (e.g. an aldehyde gives a mixture of a nitrile and a formyl derivative of an amide, a ketone gives an amide, and a fatty acid gives an amine).
[1936Proc. R. Soc. A. CLIV. 54 The introduction of the Schmidt method leaves the Hofmann method of great historical interest but deprives it of importance for costly and delicate synthetic work.] 1937Jrnl. Amer. Chem. Soc. LIX. 2658/1 Although the Schmidt reaction has been used in a few instances it has never been extensively studied. 1963I. L. Finar Org. Chem. (ed. 4) I. ix. 178 Schmidt's reaction with acids is a modification of the Curtius reaction. 1967L. F. & M. Fieser Reagents for Org. Synthesis I. 447 Application of the Schmidt reaction to cyclohexanone effects ring enlargement to ε-caprolactam. 1976Streitwieser & Heathcock Introd. Org. Chem. xxviii. 825 The Schmidt reaction may also be used for the synthesis of simple amino acids if it is applied to an alkylated malonic acid.
▪ II. Schmidt2 Astr.|ʃmɪt|
The name of Bernhard Voldemar Schmidt (1879–1935), Estonian-born German optician, used attrib. with reference to an optical system invented by him, as Schmidt camera, an astronomical telescope, used exclusively for wide-field photography at the primary focus, in which a Schmidt correcting lens is placed at the centre of curvature of a spherical primary mirror, the combination having no spherical aberration and little chromatic aberration; Schmidt correcting lens, corrector, (correcting) plate, an aspheric lens of complex figure used in the Schmidt camera and other catadioptric systems that utilize the same principle; Schmidt telescope = Schmidt camera. Also ellipt. = Schmidt camera.
1939Skilling & Richardson Astron. iii. 82 The great advantages of the Schmidt telescope are that it can photograph a very large area in the sky, giving sharp focus clear to the edge of the picture; and that it is very fast. Ibid., These telescopes are sometimes called Schmidt cameras, for they cannot be used visually. 1946Nature 17 Aug. 222/1 A Schmidt plate presents a very different problem, since the highest optical homogeneity is required for this, and a low-expansion glass has never yet been produced in the requisite optical quality. 1961Miczaika & Sinton Tools of Astronomer iii. 99 (caption) Possible shapes of Schmidt correcting lenses. Ibid. 100 Such solid Schmidts, as they are called, may be made with f-numbers as small as f/o·6. 1964Listener 21 May 831/1 The Armagh Schmidt is employed mainly on variable star research. 1966McGraw-Hill Encycl. Sci. & Technol. XIII. 452/1 A similar correction of the principal defects of the paraboloidal reflector can be obtained by replacing the thin Schmidt correcting plate with a weakly diverging meniscus lens. 1973Sci. Amer. Aug. 111/1 Schmidt correctors and other aspheric surfaces are sold by the tens of thousands in quality zoom lenses for film and television. 1978Pasachoff & Kutner University Astron. iv. 90 The 1·2-meter Schmidt has been used to map the entire sky that is visible from Palomar. Ibid., The new 1-meter Schmidt camera at the European Southern Observatory and the British 1·2-meter Schmidt camera at Siding Spring, Australia, are now being used in a joint project to extend the survey to incorporate the one-quarter of the sky that cannot be seen from Palomar. 1978Sci. Amer. Dec. 90/3 The lens of the scallop eye appears to perform much the same function as the corrector plate of the Schmidt telescope. |