Organic 2 Review Problem 176

Organic 2 Review Problem 176 - higher melting-points than...

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i6o PRACTICAL ORGANIC CHEMISTRY (c) if Y is in a lower group than X, (d) if X and Y are atoms of the same element, (e) if the group XY consists of i atom alone. To apply those rules, only the elements given in the accompanying Table need usually be considered. Hydrogen is Group I IV V VI VII considered as being in Group I: if Y consists HCNO F solely of hydrogen atoms, the latter obey the S Cl above rule; if, however, Y consists partly of Br hydrogen and partly of another element, both I attached to X (as in - CHO), then the influence of the hydrogen can usually be ignored and the rules applied to the remaining element alone. Examples of the above classes are: Meta directing: (a) -CHO, -COOH, -CN, -CCl 3 , -NO 2 . (6) -SO 2 OH. Ortho and para directing: (c) -CH 3 , -OH, -OCH 3 , -NH,, -NHCOCH 3 , -SCN. (d) -CH 8 -CH 3 (X and Y being the C'C atoms). -CHrCHCOOH (X and Y being the C:C atoms). -N:N - (X and Y being the N:N atoms). M -Cl, -Br, -I. The student should remember that para compounds have almost invariably
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Unformatted text preview: higher melting-points than the corresponding ortho and meta isomerides, as the following examples show: Melting-points of Disubstitilted Benzenes Ortho Meta Para Dichloro-benzene C 6 H 4 Cl 2-17 -25 53 Chloro-bromo-benzene C fl H 4 ClBr 12 -21 67 Dibromo-benzene C 6 H 4 Br 2 6 -7 89 Chloro-aniline C 6 H 4 ClNH 2-2-10 70 Bromo-aniline C 6 H 4 BrNH 3 31 18 66 Nitro-aniline C 6 H 4 (NO 2 )NH 2 72 114 148 Bromo-phenol C 6 H 4 Br(OH) 5 32 63 Nitro-phenol C 6 H 4 (NO 2 )OH 46 97 114 Bromo-toluene C 6 H 4 BrCH 3-26 -40 28 Nitro-toluene C 6 H 4 (CH 3 )NO 2-4 16 52 Toluene sulphonylchloride C 6 H 4 (CH 3 )SO 2 Cl 10 12 66 It will be seen that the para compound is frequently the only isomeride which is solid at room temperature, a fact which should be borne in mind when identifying organic compounds. m-Dinitrobenzene. C 6 H 4 (NO 2 ).,. Required: Fuming nitric acid, 15 ml.; sulphuric acid, 20 ml.; nitrobenzene, 12 ml....
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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