thought id share some info to BB
Hydrogen peroxide is conveniently prepared by slowly adding 10 grams of barium peroxide to 50ml of ice cold, 20 percent by weight sulphuric acid. The addition is carried out in small portions with good stirring. Additionally, pieces of ice are added to the reaction mixture. During the addition, barium sulphate will precipitate. After the additon is completed, barium carbonate is added to remove the excess of sulphuric acid. Therafter, the mixture is filtered to recover the aqueous solution of hydrogen peroxide.
Refernce: Jander / Blasius: “Einführung in das anorganisch – chemische Praktikum”, S. Hirzel Verlag Stuttgarte, 15. Auflage 2005, page 106
Concentrated hydrogen peroxide may explode!!! A 500-ml. distilling flask is provided with a standard male ground joint, onto which is placed a female glass cap, equipped with a distillation capillary. The side tube of the capillary is connected with ground joints to a spiral condenser, which empties into a receiver of about 200-ml. capacity. After the introduction of 180 ml. of Perhydrol (stored in bottles coated with paraffin wax), the flask is placed on a water bath (45 to 50°C) and the material is distilled over a period of about 3.5 hours at a pressure of 16 to 22 mm. Thus, about 150-160 ml. of water and some hydrogen peroxide are removed. The residue contains approximately 98% H2O2. The volume of water to be distilled may be marked off on the previously tared receiving flask. (If the temperature of the water bath rises above 52°C, the concentrated H2O2 turns yellow and should be discarded.) The concentrated product may be removed from the flask without any danger of decomposition. (If a female ground joint were to be used at the neck of the flask, the decomposition on the rough surface would be appreciable.).
By another method 80-90% hydrogen peroxide starting material can also be obtained by mixing 30% hydrogen peroxide solution with twice its amount of p-cymene, followed by distillation of the mixture at 50°C, using an aspirator vacuum. Most of the water and p-cymene is thus removed. After mechanical separation of the remaining p-cymene-H2O2 mixture, further processing is carried out as described above.
Reference: G. Brauer, Handbook of Preparative Inorganic Chemistry, Vol 1, 140-141 p, Academic Press, New York, 1965.
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Isomerisation of crude sulphur turpentine
A mixture of crude sulphur turpentine (500 mL) and diluted aqueous sulphuric acid (100 mL, 36 %) was stirred at 110 °C for 5 hours. The aqueous layer was removed in a separatory funnel. The isomerized organic material was purified from heavier (polymerized) material by distillation under reduced pressure (5 hPa; 70-80 °C) and obtained in 76% yield.
Example 2
Oxidation of mixture of terpinenes to p-cymene A solution of FeCI3*6H20 (31 g, 0.24 eq.) in water (60 mL) was added to a solution of the isomerized material of Example 1 (80 mL, 64 g) in p-cymene (79 mL, 63 g). The resulting mixture was heated at 90 °C and vigorously stirred under air for 1.5 hours. The product was isolated from the crude organic reaction mixture by distillation under reduced pressure (5 hPa; 70-80 °C) and obtained in 29% yield (corrected for the amount of p-cymene added as solvent).
Example 3
Oxidation of mixture of terpinenes to p-cymene
FeCI3*6 H20 (2,5 g) and diluted aqueous hydrochloric acid (10 mL, 13%) were added to the isomerized material of Example 1 (10 mL, 8 g). The resulting two-phase system was heated at 90 °C and vigorously stirred under air for 40 hours. The yield of p-cymene in the crude reaction mixture was 16.2%, as determined by gas chromatography.
Hydrogen peroxide is conveniently prepared by slowly adding 10 grams of barium peroxide to 50ml of ice cold, 20 percent by weight sulphuric acid. The addition is carried out in small portions with good stirring. Additionally, pieces of ice are added to the reaction mixture. During the addition, barium sulphate will precipitate. After the additon is completed, barium carbonate is added to remove the excess of sulphuric acid. Therafter, the mixture is filtered to recover the aqueous solution of hydrogen peroxide.
Refernce: Jander / Blasius: “Einführung in das anorganisch – chemische Praktikum”, S. Hirzel Verlag Stuttgarte, 15. Auflage 2005, page 106
Concentrated hydrogen peroxide may explode!!! A 500-ml. distilling flask is provided with a standard male ground joint, onto which is placed a female glass cap, equipped with a distillation capillary. The side tube of the capillary is connected with ground joints to a spiral condenser, which empties into a receiver of about 200-ml. capacity. After the introduction of 180 ml. of Perhydrol (stored in bottles coated with paraffin wax), the flask is placed on a water bath (45 to 50°C) and the material is distilled over a period of about 3.5 hours at a pressure of 16 to 22 mm. Thus, about 150-160 ml. of water and some hydrogen peroxide are removed. The residue contains approximately 98% H2O2. The volume of water to be distilled may be marked off on the previously tared receiving flask. (If the temperature of the water bath rises above 52°C, the concentrated H2O2 turns yellow and should be discarded.) The concentrated product may be removed from the flask without any danger of decomposition. (If a female ground joint were to be used at the neck of the flask, the decomposition on the rough surface would be appreciable.).
By another method 80-90% hydrogen peroxide starting material can also be obtained by mixing 30% hydrogen peroxide solution with twice its amount of p-cymene, followed by distillation of the mixture at 50°C, using an aspirator vacuum. Most of the water and p-cymene is thus removed. After mechanical separation of the remaining p-cymene-H2O2 mixture, further processing is carried out as described above.
Reference: G. Brauer, Handbook of Preparative Inorganic Chemistry, Vol 1, 140-141 p, Academic Press, New York, 1965.
....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Isomerisation of crude sulphur turpentine
A mixture of crude sulphur turpentine (500 mL) and diluted aqueous sulphuric acid (100 mL, 36 %) was stirred at 110 °C for 5 hours. The aqueous layer was removed in a separatory funnel. The isomerized organic material was purified from heavier (polymerized) material by distillation under reduced pressure (5 hPa; 70-80 °C) and obtained in 76% yield.
Example 2
Oxidation of mixture of terpinenes to p-cymene A solution of FeCI3*6H20 (31 g, 0.24 eq.) in water (60 mL) was added to a solution of the isomerized material of Example 1 (80 mL, 64 g) in p-cymene (79 mL, 63 g). The resulting mixture was heated at 90 °C and vigorously stirred under air for 1.5 hours. The product was isolated from the crude organic reaction mixture by distillation under reduced pressure (5 hPa; 70-80 °C) and obtained in 29% yield (corrected for the amount of p-cymene added as solvent).
Example 3
Oxidation of mixture of terpinenes to p-cymene
FeCI3*6 H20 (2,5 g) and diluted aqueous hydrochloric acid (10 mL, 13%) were added to the isomerized material of Example 1 (10 mL, 8 g). The resulting two-phase system was heated at 90 °C and vigorously stirred under air for 40 hours. The yield of p-cymene in the crude reaction mixture was 16.2%, as determined by gas chromatography.