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
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Licence: Public Domain Mark

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.

    451/490 (page 429)
    cyanide must be decomposed by metallic zinc. Prussian blue test : Add ferrous sulphate, ferric chloride, caustic soda, and warm, then excess of dilute hydrochloric acid. Thiocyanate test: Evap. hydrocyanic acid to dry- ness with yellow ammonium sulphide, without overheating ; ferric chloride gives red ferric thiocyanate. Silver test: Silver cyanide, like silver chloride, insol. in nitric acid, sol. in ammonia, but sol. in excess of cyanide. Last three tests best with watch-glass inverted over small beaker containing cyanide, and warm dilute hydrochloric acid. Watch-glass smeared with caustic soda, ammonium sulphide or silver nitrate ; leave 3 minutes. [.Estimation of Hydrocyanic Acid.—Potassium or hydrogen cyanide dis- solved in, or diluted if necessary with, water, and rendered just faintly alkaline hy the addition of dilute nitric acid (to highly alkaline potassium salt) or caustic soda, and kept in this state throughout operation (solution coloured with litmus). Silver solution (4'25 grams per 250 c.c. = AgNOs/10 per litre) quiclcly run in until slight permanent ppt. of AgCN. KCN thus converted into double cyanide AgCN, KCN. 1 c.c. silver=0'0054 grams hydrogen cyanide (=2HCN/10).] Mercuric Cyanide and Cyanogen.—9 grams dry powdered mercuric sul- phate stirred into hot solution of 6 grams cryst. potassium ferrocyanide in 40 c.c. water. Boil gently, filter hot. Mercuric cyanide separates at once. Recrystallise from water, filtering. Dry on filter paper. Salt does not give tests for mercury or cyanides until decomposed with zinc. Cyanogen : Heat dry crystals in small test tube, note inflammable gas, pink flame. Cyanogen is intensely poisonous. Ethyl Isocyanate.—Heat a little ethyl sodium sulphate with potassium cyanate in dry test tube. Note pungent unpleasant odour of isocyanate. Methyl isocyanide already incidentally formed in synthesis of acetic acid. Ammonium Thiocyanate.—20c.c. cone, ammonia, 20 c.c. meth. spirit, 3c.c. carbon bisulphide. Proceed as directed. Evaporate residue to dryness on w.-b., extract with hot spirit, crystallise and test. Mustard Oil (see Aniliue).—From methylamine or ethylamine and carbon bisulphide (1 drop), warmed with ferric chloride. CHAPTER XXXV Methylamine.—5 grams acetamide mixed with 4J c.c. bromine, and 5 grams in 50 c.c. caustic coda in 50 c.c. water added till yellow product. Run this through thistle funnel into distilling flask containing 12 grams caustic soda in 36 c.c. water at 70°—not above. Condenser to dip under little water in receiver. Then proceed as in chapter x. for methylamine hy drochloride crystals. CHAPTER XXXVI Glycosine.—From 5 grams hippuric acid and 10 c.c. cone, hydrochloric acid as directed. Suspend lead glycosine in water and evaporate filtered solution on w.-b. Note m.-pt. and methylamine with soda-lime (odour and inflammability). Nitrogen with nitrous acid, as with ethylamine. Dissolve some freshly ppt. copper oxide in solution of 4 gram, and evap. filtered solu- tion for copper amido-acetate. [From 10 grams chloracetic acid and 12 grams ammonium carbonate as directed. Compare with hippuric acid product.] CHAPTER XXXVII [Ethyl Nitrate.—Dangerous.] Ethyl Nitrite.—Warm a little alcohol with copper turnings and a few drops cone, nitric acid in a test tube, and note odour. [Nitro -methane.—Calculated quantities.] [Mercuric Fulminate.—3 grams mercury, 18 c c. cone, nitric acid, 9 c.c. water. Add 20 c.c. meth. spirit, then 20 c.c. more. Dry and detonate portion of fulminate. Convert rest into hydroxylamine hydrochloride.]