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PREPARATION VIII.

Nitraniline.-Ammonium sulphide is selected here as the reducing agent, on the ground that the action is slow, and may be interrupted after one nitroxyl group has been reduced.

PREPARATION IX.

Diethylaniline.—The tertiary aromatic bases, although analogous in composition to the tertiary amines of the fatty group, have, like the primary bases, less basic properties (Prep. IV.), due probably to the negative character of the radical "phenyl" (Ber. 20, 534). The formation of the "nitrosamine" compound described in the footnote to this preparation is characteristic of all secondary amines or imido-compounds. The "nitrosyl " group (NO) takes the place of the hydrogen atom in the imidogroup, = NH, to form nitrosamine, N.NO.

PREPARATION X.

Nitrosodimethylaniline.—The action of nitrous acid on tertiary amines occurs in the case of aromatic compounds only.

PREPARATION XI.

p-Nitrosophenol.—This compound is also formed by the action of nitrous acid on phenol. Liebermann's reaction is only applicable to aromatic "nitroso" compounds or "nitrosamines of the fatty series.

PREPARATION XII.

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Potassium Benzene Sulphonate.—The action of conc. sulphuric acid on aromatic hydrocarbons is analogous to that of conc. nitric acid. One or more hydrogen atoms of the benzene nucleus are replaceable by the sulphoxyl group (SO,H) and water is

eliminated. The substitution of a second and third H atom becomes a more difficult operation, and the action is brought about by the use of the fuming acid containing a large percentage of SO, or in conjunction with P2O5. The free sulphonic acid may be obtained by precipitating the lead salt with H2S, or the barium salt with sulphuric acid and evaporating the filtrate.

PREPARATION XIII.

Phenol. The replacement of the sulphoxyl group by hydroxyl by fusion with caustic potash is generally applicable to the preparation of this class of bodies (naphthol from naphthalene sulphonic acid, oxyquinoline from quinoline sulphonic acid, &c.). The action of the two alkalis (NaOH. KOH) is not identical. Whereas with potash molecular change may occur, i.e. the hydroxyl does not necessarily take the place of the sulphoxyl group (resorcinol is formed from o-benzene disulphonic acid), this is not so often observed with caustic soda. The latter bas, however, a greater oxidising action, so that, for example, by fusing resorcinol CH(OH), with caustic soda phloroglucinol CH(OH)3 is formed (Barth, Schreder). The phenols are also formed from halogen substitution products of benzene by fusion with caustic potash. Compare the latter reaction with that of the fatty compounds.

PREPARATION XIV.

Anisol.-A characteristic property of the hydroxyl group (OH) is that the hydrogen is replaceable by alcohol or acid radicals, forming acid and alcohol ethers. This is true of alcohols (Prep. XLIV.), phenols, and acids (Prep. XLII. and LVII.). The phenol ethers are split up into phenol and chloride or iodide of the alcohol radical by heating with HCl or HI to a high temperature (in sealed tubes), CHOCH ̧ + HI = CH2I +

C6H5OH. This reaction has been made the basis of a quantitative method for determining the number of methoxyl-groups (-OCH3) present in a compound.

PREPARATION XV.

O- and p-Nitrophenol.-Compare the action of nitric acid on benzene.

PREPARATION XVI.

Picric Acid.-The strongly negative or acid character of the II in the hydroxyl group is due to the presence of the three nitroxyl groups. (Compare the di- and trinitro-derivatives of the paraffins.) Picric acid behaves like an organic acid in decomposing the alkaline carbonates to form salts. In this respect it differs from non-substituted phenols, which combine only with the caustic alkalis.

PREPARATION XVII.

Phenolphthalein.—The action of conc. sulphuric acid is that of a dehydrating agent; that is to say, it withdraws the elements of water from the reacting substances. The reaction, which occurs in this way between organic compounds, resulting in the formation of more complicated bodies, in which the carbon atoms form the connecting link, is termed "condensation." The condensation products produced by similar dehydrating agents (ZnCl2, anhydrous oxalic acid, SnCl4, NaOH, &c.) form a large chapter in organic chemistry.

PREPARATION XX.

Benzyl Chloride.—The chlorination of the toluene is conducted at a high temperature, and takes place therefore in the side chain. By continued action the whole of the three hydrogen

N

At

atoms of the methyl group may be replaced by chlorine. the ordinary temperature, or in presence of a little iodine, the substitution occurs in the benzene nucleus.

PREPARATION XXI.

Benzaldehyde.—In addition to the reactions cited at the end of the preparation, the compounds, which benzaldehyde forms with HCN and hydroxylamine are characteristic alike of all aldehydes and ketones. In the former case compounds of the general OH

formula R1C<

CN

are produced, which may be readily converted

into an oxy-acid containing a carbon atom more than the original compound (Prep. XXIII.). In the latter reaction the hydroxylamine combines (water being eliminated) to form a compound of the general formula = C:N.OH. In the case of aldehyde the compound thus formed has received the name of aldoxime (aldehyde-oximido) in that of certain ketones acetoxime (acetone-oximido), and similarly glyoxime and quinonoxime (Prep. XI.). A further property of the " carbonyl" group (CO), common to aldehydes and ketones, is that the oxygen atom by the action of PCl5 is replaceable by two atoms of chlorine. Benzaldehyde yields benzylene chloride, C6H5CHC12 Aldehydes readily form condensation products (Prep. XXXVI.).

PREPARATION XXII.

Benzyl Alcohol.-The action of caustic potash on aldehydes to form alcohol and acid is not equally applicable to fatty aldehydes. In the latter case, especially with the lower members of the series, resinous products are formed.

PREPARATION XXIII.

a-Toluic Acid.-The property of nitrils to yield an acid with the same number of C atoms, by the action of mineral acids or

alkalis, is common to fatty and aromatic compounds (Preps. XLVIII., LXVI.).

PREPARATION XXIV.

Oxybenzaldehyde..-"Reimer's reaction" for the preparation of oxyaldehydes from phenols is applicable to a very large number of monhydric and polyhydric phenols. The substitution of two H atoms by two aldehyde groups sometimes occurs as in the case of resorcinol. An analogous reaction is that of potash and carbon tetrachloride on phenol with the formation of oxybenzoic acid.

PREPARATION XXV.

Acetophenone.-The production of ketones by the dry distillation of certain organic salts (Ca or Ba salts) occurs also in the case of fatty acids. If a formate be one of the salts employed, an aldehyde is obtained thus: H.COOM1 + C ̧Н¿COOM1 = C&H COH+M,'CO.

=

PREPARATION XXVI.

Benzoin. This preparation affords an interesting example of molecular change and polymerisation produced by the action of potassium cyanide. Furfurol, CHÃO.COH, forms, under like conditions, a similar compound (furoin). The reducing action of benzoin on Fehling's solution is shared by aldehydes and hydrazines, and also those bodies (the sugars) which, like benzoin, contain the ketone alcohol group, CO.CH2(OH).

PREPARATION XXVIII.

Benzoyl Chloride.-The substitution of hydroxyl (OH) by Cl, by the action of PCl, or PC15, applies to all classes of organic compounds, and the fact is therefore made use of in ascertaining the presence of this group.

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