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Fiche 1,  Justifications,  Anglais

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ortho: A prefix meaning "straight ahead"; "meta" means "beyond"; "para" means "opposite". These prefixes are used in organic chemistry in naming disubstitution products derived from benzene in which the substituent atoms or radicals are located in certain definite positions on the benzene ring. This is illustrated in the diagram [not reproduced on this record], where A and B represent the substituent atoms or groups. When attached to adjoining carbon atoms, B is in the ortho position in respect to A (also called the 1,2-position). If B is located on the third carbon atom in respect to A, it is in the meta position (also called 1,3-); when B is attached to the opposite carbon atom, it is the para position (1,4).  3, fiche 1, Anglais, - 1%2C2%2D

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The prefixes "ortho-", "meta-" and "para-", along with their corresponding abbreviations ("o-", "m-" and "p-"), appear in italics and are ignored in alphabetizing. According to the actual chemical nomenclature rules in organic chemistry (in 2003), the numbers designating the positions of the disubstitution groups (1,2- for "ortho-", 1,3- for "meta-" and 1,4- for "para-") are to be preferred to the symbols "o-", "m-" and "p-". Furthermore, the prefixes "ortho-", "meta-" and "para-" should not be used anymore, and their corresponding abbreviations ("o-", "m-", and "p-") will soon be judged to be avoided, if not totally condemned.  1, fiche 1, Anglais, - 1%2C2%2D

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In inorganic chemistry the prefix ortho- designates the most highly hydrated acid, or its salt, to contrast with the meta-, or less hydrated acid or salt.  3, fiche 1, Anglais, - 1%2C2%2D

Fiche 1,  Justifications,  Français

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Préfixe qui s'applique aux dérivés du benzène substitués aux positions 1 et 2.  3, fiche 1, Français, - 1%2C2%2D

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[Aussi :] Préfixe qui s'applique aux acides minéraux et organiques portés à un degré supérieur d'hydratation.  3, fiche 1, Français, - 1%2C2%2D

Record number: 1, Textual support number: 2 OBS

Les préfixes de position «ortho-», «méta-» et «para-», tout comme les abréviations correspondantes «o-», «m-» et «p-», s'écrivent en italique et n'interviennent pas dans une classification par ordre alphabétique. Selon les règles de nomenclature de chimie organique en vigueur aujourd'hui (en 2003), il est recommandé d'utiliser les chiffres 1,2-, 1,3- et 1,4-, respectivement. Les préfixes «ortho-», «méta-» et «para-» ne doivent plus être utilisés. L'usage des symboles correspondants («o-», «m-» et «p-») sera bientôt fortement déconseillé, sans être exclu.  1, fiche 1, Français, - 1%2C2%2D

Fiche 1,  Justifications,  Espagnol