. Elements of modern chemistry . as shown that if but a single atom of hydrogenin benzene be replaced by another monatomic atom or group, theresulting compound does not vary, and is incapable of is not, however, the case if two hydrogen atoms be re-placed, for theory then predicts, and experiment confirms, theexistence of three isomeric compounds in each case. Thisisomerism results from the different positions of one of thesubstituted atoms or groups with relation to the other in their 65* I 654 ELEMENTS OP MODERN CHEMISTRY. attachment to the benzene nucleus. Let X and Y be the
. Elements of modern chemistry . as shown that if but a single atom of hydrogenin benzene be replaced by another monatomic atom or group, theresulting compound does not vary, and is incapable of is not, however, the case if two hydrogen atoms be re-placed, for theory then predicts, and experiment confirms, theexistence of three isomeric compounds in each case. Thisisomerism results from the different positions of one of thesubstituted atoms or groups with relation to the other in their 65* I 654 ELEMENTS OP MODERN CHEMISTRY. attachment to the benzene nucleus. Let X and Y be the twosubstituted monatomic atoms or groups, such as chlorine, hy-droxyl, nitryl, etc., then the isomerism would be expressed asfollows: cx ox ex CH CH The position at 1 being always supposed to be occupied byone of the substituted groups, the compounds are named ortJioif the other replacement be at 2 or 6, meta if it be at 3 or 5,and jpara if it be at 4. The relations of 2 and 6 to 1 are thesame, as are also those of 3 and 5 to ortho, meta ortho meta para In the preceding compounds formed by X and Y, these po-sitions would be marked as follows: C6H4< X(i) -Y(2)Ortho-derivative. C6H*< X(i) -Y(3)Meta-derivative. C6H4< X(i) -Y(4)Para-derivative. The following examples will further explain this isomerismof position, of which we must study numerous cases. ORTHO-SERIES. X(i) CY(2) HC CH \ / C H ^ ^ <CH3(2) Orthoxylene. C6H4<-CH3(i) ^ ^ \0H(2) Orthocresol. META-SERIES. PARA-SERIES. X(i) X(i) c c / \ y x. HC CH HC CH HC CY(3) HC CH \ / \ / C C H Y(4) ^ ^ CH3(3) r6me-CH3(i)^^<CH3(4) Metaxyleue. Paraxylene. r6m^C!H3(i)^^<0H(3) ^ ^ <0H(*) Metacresol. Paracresol. AROMATIC COMPOUNDS. 655 ^ ^ ^0H(2)Orthodiphenol.(pyrocatechine.) ^ ^ ^(2) Orthoxybenzoic acid. (salicylic.) ^ ^ ^NH2(2) Orthophenylene diamine. ^ ^ ^(2)Orthoamidobenzoic acid. C6H4^(i) ^ \(2) Phthalic acid. ^ ^ <0H(3) Metadiphenol. (resorcine.) C6H4< OH(i) (3)Metoxybenz
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Keywords: ., bookcentury1800, bookdecade18, booksubjectchemistry, bookyear1887
