2,6-Dimethylaniline

DImethylaniline is a pale yellow, highly refractive, toxic, oily liquid with a pungent odor. 

It is soluble In ethyl alcohol, ethyl ether, and carbon tetrachloride, but only very slightly soluble In water. It is used in the making af dyes and the explosive tetranitroanlllne ( Tetryl ). 

Boiling point Freesing point Specific gravity at 25/25 C Weight per gallon at 25 C Boiling range within 

Place 28 g. (27-5 ml.) of pure aniline and 28 g. (23 ml.) of purified methyl phosphate in a 500 ml. round-bottomed flask equipped with a reflux condenser. Heat gently at first and remove the flame when the vigorous and exothermic reaction commences. When the latter subsides. 

Diethylaniline. Use 28 g. of pure aniline and 36 g. (34 ml.) of purified ethyl phosphate, and proceed exactly as described for dimethylaniline. The reaction is not so vigorous initially. Separation into two layers occurs after 30 to 90 minutes. The yield of diethylaniline, b.p. 215-216°, is 41-5 g. 

Pure dimethylaniline from commercial dimethylaniline. Into a 250 ml. round-bottomed flask fitted with a reflux condenser place 50 g. (52-5 ml.) of a good commercial sample of dimethylaniline and 25 g. (23 ml.) of acetic anhydride. Heat vmder reflux for 3 hours, and allow to cool. Transfer to a 100 ml, Claisen flask equipped for distillation, and distil using a wire gauze or, better, an air bath (Fig. II, 5, 3). Some acetic acid and the excess of acetic anhydride passes over first, followed by pure dimethylaniline (a colourless liquid) at 193-194°, There is a small dark residue in the flask. The yield depends upon the purity of the commercial sample, but is usually 30-40 g. 

Pure diethylaniline from commercial diethylaniline. Use 50 g. (53-5 ml.) of a good commercial specimen of diethylaniline and 25 g, (23 ml.) of acetic anhydride, and reflux for 4 hours. Distil and collect the pure diethylaniline at 216-217° as a pale yellow liquid. The yield is 30-40 g. 

Checked by N. L, Drake, Wilkins Reeve, and John Steeling, Js. 

In a 1.1-1. steel reaction vessel (Note 1) are placed 200 g. (1.08 moles) of 4-bromo-tf-xylene (p. 22), 14 g. copper wire, and 600 ml. (540 g., 9.0 moles) of 28% ammonia containing 12 g. of cuprous chloride. The steel reaction vessel is heated and rocked at 195° 

A hydrogenation vessel supplied by the American Instrument Company is satisfactory. A certain amount of copper plates out on the walls of the bomb during the reaction, but most of it is removed when the apparatus is cleaned. 

The heating and rocking are carried out in a hydrogenation assembly. The temperature must not be allowed to exceed 200° at higher temperatures decomposition occurs and the yield suffers. 

The optimum reaction time may vary slightly with apparatus of different types. 

Use of Benzenesulphonyl Chloride in Distinguishing the Three Types of Amines (SECTION 473).—Shake together for 2 or 3 minutes 0.5 cc. of aniline, 50 cc. of a strong aqueous solution of sodium hydroxide (1 to 4) and 2 cc. of benzenesulphonyl chloride. Warm gently until the odor of the chloride disappears. Filter and add hydrochloric acid to the filtrate. (Eqs.) 

Repeat the experiment using methylaniline and then dimethyl-aniline. Test the solubility in dilute hydrochloric acid of the substances separated in these two cases by filtration. Write equations for all reactions, and state clearly how the reagent serves to distinguish from one another the three classes of amines. 

NOTE—A few primary amines yield products with benzenesulphonyl chloride which do not dissolve in a dilute solution of sodium hydroxide. This is due to the fact that a difficultly soluble sodium salt is formed, which 

A mixture of 126 g. (1.50 moles) of dimethylaminoacetonitrile (p. 124) and 30 g. of Raney nickel catalyst [Org. Syntheses, 21, 15 (1940) ] is placed in a Parr hydrogenation bomb and agitated at around 1000 lb. hydrogen pressure and a temperature of 78°. The theoretical amount of hydrogen is absorbed in about 3 hours. The catalyst is removed by filtration, and the filtrate is fractionally distilled. There is obtained 62 g. (47%) of /3-dimethylaminoethylamine, boiling at 105-108° at atmospheric pressure. 

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On acetylation it gives acetanilide. Nitrated with some decomposition to a mixture of 2-and 4-nitroanilines. It is basic and gives water-soluble salts with mineral acids. Heating aniline sulphate at 190 C gives sulphanilic add. When heated with alkyl chlorides or aliphatic alcohols mono- and di-alkyl derivatives are obtained, e.g. dimethylaniline. Treatment with trichloroethylene gives phenylglycine. With glycerol and sulphuric acid (Skraup s reaction) quinoline is obtained, while quinaldine can be prepared by the reaction between aniline, paraldehyde and hydrochloric acid. 

Its chief importance is as a source of cinnamic acid by condensation with sodium ethan-oate and ethanoic anhydride and as a source of triphenylmethane dyestuffs by condensation with pyrogallol, dimethylaniline, etc. It is also used in the manufacture of perfumes. 

N,N-dimethylaniline, CgHuN, PhNMej. Colourless oil of characteristic smell b.p. 193"C. 

It reduces to 4-aminodimethylaniline and gives dimethylamine with hot sodium hydroxide solution. It is prepared by the action of nitrous acid upon dimethylaniline at 0 C. 

Wang 0, Akhremitchev B and Walker G 0 1997 Femtosecond infrared and visible spectroscopy of photoinduced intermolecular electron transfer dynamics and solvent-solute reaction geometries Coumarin 337 in dimethylaniline J. Rhys. Chem. A 101 2735-8... 

If, however, a tertiary amine has two alkyl groups and also an aryl group having the para position unsubstituted, then the action of nitrous acid is to insert the nitroso group directly into this para position. Dimethylaniline, for example, when treated with nitrous acid readily gives p-nitrosodimethyl-... 

Required Dimethylaniline, 15 ml. hydrochloric acid, 50 ml. sodium nitrite, 9 g. 

C,H5N,NHC,Hs+HC1 = C,H 5N C1+H,NC,H5- C H5N NC H NH +HC1 gen atom of the aniline molecule, giving aminoazobenzene. Since this reaction is irreversible, whilst the former is freely reversible, the final result is the complete conversion of the diazoaminobenzene into the aminoazobenzene. (The intermediate formation of the benzenediazonium chloride can be demonstrated by adding dimethylaniline, with which the diazonium chloride couples preferentially, giving dimethylaminoazobenzene, C6HsN NC6HiN(CH3)i.)... 

It is important in this preparation to avoid an excess of nitrous acid before coupling occurs, otherwise the excess of nitrous acid will react directly with the dimethylaniline, and the deep green p-nitrosodimethylaniline so formed will contaminate the methyl-orange. 

Required Anhydrous sodium carbonate, 2 g. sulphanilic acid, 7 g. sodium nitrite, 2-2 g. hydrochloric acid, 12 ml. dimethylaniline, 4 ml. 

Dissolve 2 g. of anhydrous sodium carbonate in 50 ml. of water contained in a 400 ml. beaker and add 7 g. of finely powdered crystalline sulphanilic acid (2H2O), warming the mixture gently in order to obtain a clear solution. Add a solution of 2 2 g. of sodium nitrite in 10 ml. of water and then cool the mixture in ice-water until the temperature has fallen to 5°. Now add very slowly (drop by drop) with continual stirring a solution of 8 ml. of concentrated hydrochloric acid in 15 ml. of water do not allow the temperature to rise above 10°. When all the acid has been added, allow the solution to stand in ice-water for 15 minutes to ensure complete diazotisation during this period fine crystals of the internal salt separate from the pink solution. Dissolve 4 ml. of dimethylaniline in a mixture of 4 ml. of concentrated hydrochloric acid and 10 ml. of water, cool the solution in ice-water, and add it slowly to the cold well-stirred diazo solution a pale red coloration is developed. Allow the mixture to stand for 5 minutes and then add slowly with stirring aqueous... 

Separation of a Mixture of Aniline, Monomethyianiline, and Dimethylaniline.f Hinsberg s Method. 

Extract the dimethylaniline by shaking the distillate in a separating-funnel with a few ml. of ether, and then dry the ethereal solution over potassium carbonate distil the filtered ethereal solution from a small distilling-flask e.g, Fig. 36, p. 63) with the usual precautions, and finally the dimethylaniline, b.p. 193°. Yield, almost theoretical. 

The following preparation of triethyl phosphite illustrates the interaction of phosphorus trichloride and ethanol in the presence of dimethylaniline the preparation of di-isopropyl hydrogen phosphite illustrates that of phosphorus trichloride and isopropanol in the absence of a tertiary amine. 

Coloured oxidation products, (a) Dissolve a few small crystals of triphenylamine in i ml. of cone. H2SO4 (cf. footnote, p. 376). Add 2 drops of cone. HNO3 to about 10 ml. of water, mix, and add i drop of this diluted HNO3 to the triphenylamine solution an intense greenish-blue coloration is produced. Dimethylaniline when treated in this way turns a deep dichromate colour. 

Forms diazonium derivative which can be coupled with 2-naphthol or with dimethylaniline to form azo-dyes. 

Formation of methyl-orange cf. p. 214). Dissolve about 0 3 g. of sul-phanilic acid in 2 ml. of 10% aqueous NajCOj solution. Cool m ice-water and add 2 to 3 drops of 20% NaNOj solution. Now add about I ml. of cold dil. HCl, shake and leave for 2-3 minutes. Meanwhile dissolve i drop of dimethylaniline in a few drops of dil. HCl, cool thoroughly in ice-water and then add to the cold diazo solution. Shake well and make alkaline with aqueous NaOH solution note the formation of a deep orange-yellow coloration or precipitate. On the addition of HCl, a bright red coloration is produced. 

Dimethylaniline. Yellow, changing through olive green to a deep green. On... 

Commercial preparations of acetyl chloride are best freed from volatile phos. phorus compounds and dissolved hydrogen chloride by redistillation from 5-10 per cent, of the volume of pure dimethylaniline. 

Method A. Pit a 1-litre three-necked flask with a mercurj -sealed stirrer, a reflux condenser, and a dropping funnel. Place 57 g. (73-5 ml.) of dry /cr<.-butyl alcohol (1), 101 g, (106 ml.) of A.R. dimethylaniline and 100 ml. of anhydrous ether in the flask, set the stirrer in motion, and... 

Secondary and tertiary amines are not generally prepared in the laboratory. On the technical scale methylaniline is prepared by heating a mixture of aniline hydrochloride (55 parts) and methyl alcohol (16 parts) at 120° in an autoclave. For dimethylaniline, aniline and methyl alcohol are mixed in the proportion of 80 78, 8 parts of concentrated sulphuric acid are added and the mixture heated in an autoclave at 230-235° and a pressure of 25-30 atmospheres. Ethyl- and diethyl-anihne are prepared similarly. One method of isolating pure methyl- or ethyl-aniline from the commercial product consists in converting it into the Y-nitroso derivative with nitrous acid, followed by reduction of the nitroso compound with tin and hydrochloric acid ... 

Tertiary aliphatic - aromatic amines, unlike those of the aliphatic series, react with nitrous acid with the formation of G-nitroso compounds the nitroso group enters almost exclusively in the para position if available, otherwise in the ortho position. Thus dimethylaniline yields />-nitrosodiniethylaniline ... 

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