Introduction to the study of organic chemistry : a text-book for students in the universitites and technical schools / by John Wade.

Wade, John.

Date:: 1898

Credit: Introduction to the study of organic chemistry : a text-book for students in the universitites and technical schools / by John Wade. Source: Wellcome Collection.

458/490 (page 436)

$Mordants.—Soak cotton rag in rosaniliue sola., drain and dry. Note colour washed out by soap. Dip rag in dilute tannin soln.; wring; dip in dil. tartar emetic soln.; wring; finally in rosaniline. Note colour now fast to soap. Repeat with picric acid and aluminium acetate (alum soln. to lead acetate soln. until all lead pptd.; use clear filtrate). Colour Base and, Leuco-Base.—All following on few milligrams only. Decolourise rosaniline soln. with cone, hydrochloric acid, and restore colour w'ith water. Ppt. white colour base with caustic soda, and redissolve in acid. Reduce dye with zinc dust and dil. hydrochloric acid. Add excess of caustic soda, and extract leuco-base with ether. Distil off ether on w.-b. and warm residue with few drops of cone, sulphuric acid ; pour into water, and note dye. [Triphenylmethane.—6Q c.c. benzene; 8 c.c. chloroform, both perfectly dry, in reflux appts.; 2 grams fresh, dry aluminium chloride added 6 times. Yield 40%. Note m.-pt. (Aluminium chloride from 5 grams aluminium foil previously boiled with 5 c.c. absolute alcohol and dried at 100° in dry air- stream ; heated to dull redness in stream of hydrogen chloride dried with cone, sulphuric acid. Expel air before heating, or explosion from hydrogen. Use chloride at once; old specimens are of no use.).] [Pararosaniline from Triphenijlmetliane.—2 grams. Not too much nitric acid or zinc dust; when excess of latter, hydrogen freely evolved.] CHAPTER LIX [Methylene Blue.—\ gram paramido-dimethylaniline in 20 c.c. water aud enough dilute sulphuric acid. Keep this solution as test. Add 2 or 3 drops and 2 or 3 drops of hydrochloric acid to solution containing trace of soluble sulphide; then ferric chloride—blue colour.] [Leuco-Malachite-Green.— 9 grams fused and powdered zinc chloride, 20 c.c. dimethylaniline, 9 c.c. benzaldehyde. After removal of excess of the aniline, cryst. leuco-base from alcohol.] [Malachite Green.—4 grams leuco-base, 200 c.c. of water, 4 c.c. cone, hydrochloric acid, 5 c.c. B.P. acetic acid. Stir in slowly ivashed lead peroxide, just pptd. by adding excess of bleaching soln. to soln. of 5 grams lead acetate. Add sodium sulphate soln. (6 grams in 30 c.c.) until no more ppt.; filter off lead sulphate and chloride. Salt out with sat. soln. of 5 grams zinc chloride until a drop of product no longer stains filter paper.] [Phenol-Phthalein.~-5 grams phthalic anhydride, 7 grams phenol, 10 c.c. cone, sulphuric acid. 2 hours boil with dil. hydrochloric acid (5 c.c., 90 c.c. water) before soda ; filter and wa.sh ; dissolve phthalem in caustic soda (ex- tract with more soda as long as soln. coloured). Finally ppt. with dil. hydrochloric acid.] CHAPTER LX Naphthalene.—Distil 10 grams commercial naphthalene, 5 grams caustic soda, 100 c.c. water with steam. Dry hydrocarbon and sublime, as with benzoic acid. Nitronaphthalene.—10 grams naphthalene, 50 c.c. glacial acetic, 10 c.c. cone, nitric acid. Recryst. washed product from alcohol. Note m.-pt. Naphthalene-P-Sulphonic Acid. — 20 grams powdered naphthalene, 14 c.c. cone, sulphuric acid in flask for 4 hours at 180°. Pour into 500 c.c. water, filter off unchanged naphthalene, and then as with ethyl sodium sulphate. Yield 80% on unrecovered hydrocarbon. a-Naphthylamine.—5 grams nitro-epd., 2 grams iron filings, 10 c.c. B.P. acetic acid. Then as with aniline (hydroxide ppt. does not redissolve). Compare with aniline. P-Naphthol.—5 grams sodium sulphonate, 15 grams caustic soda, 1 c.c. water. Temperature 200° for an hour, and finally 300° for a few minutes. Cold melt dissolved in 500 c.c. hot water, and naphthol pptd. from filtered$