| 单词 |
ortho |
| 释义 |
ortho, a. (adv.)|ˈɔːθəʊ|
[f. ortho-.]
1. Chem. (Now usu. italicized.) Characterized by or relating to (substitution at) two adjacent carbon atoms in a benzene ring; at a position adjacent to some (specified) substituent in a benzene ring. Also as adv.
1876Jrnl. Chem. Soc. I. 240 An influence is exercised by the NO2-group in favouring the displacement of Cl, Br,..&c., only when it is in the ortho (1:2) or para (1:4) position relatively to one or other of these radicles. 1903Walker & Mott tr. Holleman's Text-bk. Org. Chem. II. 347, 1:2 = 1:6 substitution-products are called ortho-compounds. 1920Conquest Apr. 260/3 The ortho acid is the one of use to the Saccharin manufacturer, the para form producing a compound of very slight sweetening power. 1924[see meta a.]. 1938L. F. Fieser in H. Gilman Org. Chem. I. ii. 73 The ortho coupling and ortho bromination of phenols involve substitution at the carbon atom connected to that carrying the hydroxyl group by a double linkage. 1949[see orient v. 4 a]. 1968G. E. Coates et al. Princ. Organometallic Chem. ii. 26 Contrast the effect of heat on mercuric benzoate, when substitution of the aromatic ring ortho to the carboxyl group occurs. 1971J. D. Roberts et al. Org. Chem. xx. 573 Halogen substituents..strongly orient ortho and para through conjugation of the unshared electron pairs.
2. Photogr. [f. orthochromatic a.] Orthochromatic. Also ellipt., an orthochromatic plate.
1904G. B. Shaw Let. 26 July (1972) II. 435, I have..a box of half-plate extra-rapid Ortho plates which I got 6 months ago. 1906Westm. Gaz. 17 May 14/2 The Barnet medium ortho is about half the speed of the well-known extra-rapid Barnet ortho-plate... For the best results the Barnet ortho screen is recommended. 1921Glasgow Herald 27 Apr. 9, I have said something in previous articles about ortho plates. 1956E. Mytum Introd. Photogr. Materials iii. 58 If the emulsion is optically sensitized by a dye which absorbs green and yellow light, it is said to be orthochromatic, often abbreviated to ‘ortho’.
3. See ortho- 3. |
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