Since the content of gasoline dienes is already known, how can the diene value be determined quickly?

Want to quickly obtain the diene value content

Determination of diene content in oils 1 Purpose: To determine the content of dienes in oils. 2 Principle: Maleic anhydride, also known as succinic anhydride, is a white crystal with an irritating odor. The dienes in gasoline can undergo an addition reaction with maleic anhydride; this is a 1:1 stoichiometric reaction. To accelerate the reaction rate, an iodine-toluene solution is added as a catalyst. After the addition reaction is complete, water is added to the mixture to hydrolyze any remaining maleic anhydride. At this point, the solution becomes acidic, and phenolphthalein is used as an indicator for titration with sodium hydroxide. The amount of sodium hydroxide consumed corresponds to the concentration of maleic anhydride present. 3 Safety: Please wear protective gloves and a mask. 4 Instruments: 4.1 HH-2 type electric water bath; 4.2 250ml ground-necked Erlenmeyer flask (with condenser); 4.3 Separatory funnel: 250ml; 4.4 Pipettes: 0.2, 10, 20ml; 4.5 Measuring cylinders: 5, 25mL. 5 Reagents and solutions: 5.1 Reagents: Unless otherwise specified, the reagents used in this method are of analytical grade. 5.1.1 Succinic anhydride: Prepare a succinic anhydride-toluene solution at a concentration of 30 g/L. 5.1.2 Toluene Note: Toluene is toxic; it is a volatile hydrocarbon, and inhaling its vapors or having skin contact with it can lead to absorption into the body. Skin contact should be avoided, and it should be used in well-ventilated conditions. 5.1.3 Sodium hydroxide Note: Sodium hydroxide is a strongly alkaline compound; direct skin contact with its solid form can cause mild alkaline corrosion, so it is necessary to wear protective gear when using it. 5.1.4 Phenolphthalein 5.1.5 Iodine 5.2 Preparation of solutions 5.2.1 Adipic anhydride-toluene solution: Weigh 30 g of anhydrous adipic anhydride, dissolve it in warm toluene (at a temperature of 60–70°C), cool the solution, then bring the volume to 1000 mL with toluene. Allow the solution to stand for 24 hours, and filter it before use. 5.2.2 Iodine-toluene solution: Weigh 12.7 g of elemental iodine, dissolve it in toluene, bring the volume to 1000 mL with toluene, mix well, and store it in a brown bottle. 5.2.3 0.5 mol/L sodium hydroxide solution: Weigh 20 g of solid sodium hydroxide, dry it at 120°C for 2 hours, then dissolve it completely in 1000 mL of carbon dioxide-free distilled water for calibration purposes. 5.2.4 Weigh 3.0 g of potassium hydrogen phthalate, accurate to 0.0001 g, and dry it at 105–110°C until a constant weight is reached. Add 80 mL of carbon dioxide-free water, two drops of phenolphthalein indicator, and titrate with the prepared sodium hydroxide solution until a pink color appears; a blank test should also be conducted. C—Concentration of sodium hydroxide; m—Mass of potassium hydrogen phthalate, in grams; V1—Volume of sodium hydroxide used for calibration, in mL; V2—Volume of sodium hydroxide used in the blank test, in mL. 6. Procedure: 6.1 Before starting the test, heat the water bath to 90±2C. 6.2 Using a pipette, accurately transfer 20 ml of the maleic anhydride-toluene solution into a 250 ml Erlenmeyer flask. Add the oil sample accurately (5–10 ml for finished oil, 1–2 ml for crude oil), then add 0.5 ml of 0.1 mol/L iodine-toluene solution. Seal the flask with a condenser having standard threads, place it in the water bath, and heat it under reflux for 1.0 hour. 6.3 After the reaction is complete, allow the Erlenmeyer flask to cool slightly, then add 10 ml of freshly boiled and cooled distilled water from the top of the condenser, and continue refluxing for 10 minutes. 6.4 After hydrolysis, cool to room temperature without removing the condenser; add 5 ml of ether and 20 ml of water from the top of the reflux condenser, making sure to rinse the walls of the condenser as much as possible while adding the ether and water. 6.5 Remove the condenser, rinse the ground joint with a small amount of distilled water, carefully transfer the solution to a 250 ml separatory funnel, wash the Erlenmeyer flask three times with 15–20 ml of ether each time, and pour the washings into the separatory funnel. After shaking vigorously for 1 minute, let the mixture settle to separate the layers. Transfer the lower layer of solution to the original Erlenmeyer flask, while the upper layer is extracted three times using 10–20 ml of water each time. Use a pH test strip to check whether the last extract is acidic; if it is, continue extracting with water until it reaches neutrality. Pour the extract into the Erlenmeyer flask that contains the lower layer of solution. 6.6 Add 6 drops of phenolphthalein indicator to the extract, and titrate with a 0.5 mol/L sodium hydroxide standard solution until a light pink color is reached. 6.7 A toluene control test was conducted under the same conditions. 7 Calculation: Diene value (g iodine/100g) = In the formula: V0 – Volume of NaOH standard solution consumed in the blank test (mL) ； V — Amount of NaOH standard solution consumed by the sample (mL) ； C — Concentration of NaOH standard solution (mol/L) ； Vw——Sample volume (mL) ； ——Sample density (g/cm3). 8 Repeatability: In the same laboratory, by the same operator, using the same testing methods and instruments, two repeated measurements are conducted on the same sample. The repeatability is as follows: Content – Repeatability requirements