Transition Metal Catalysis

Experiment 5: Transition Metal Catalysis 1. basis This experiment aims to give transition metal palladium gas for diarylacetylenes synthesis. In general, the procedures constitute of 2 steps: the synthesis of atom smasher precursor for dynamical species Pd(PPh3)4 and the preparation of alkyne. Bases on the previous studies, at that place are two well-known reactions to synthesize diarylacetylenes. The first method discovered by Castro involves the use of copper acetylides. These reagents are alert by discourse of an aqueous ammonia ascendent of cupric iodide with an fermentation alcohol ascendant of monosubstituted aryl acetylenes. (eq.1) (1) The cuprous acetylides are because hardened with aryl iodides in refluxing pyridine under nitrogen atmosphere to stoichiometrically generate diaryl acetylenes. (eq. 2) (2) By using amines as solvents and CuI as a co-catalyst, the method was ameliorate to enable introducing alkyl group substituten t to the triple bond at room temperature. The second method, which was use in this experiment, was introduced by Cassar and Heck by utilizing palladium colonial to turn the reaction. (eq. 3) (3) 2. Experimental Section 2.1The catalytic Precursor Preparation A mixture of palladous chloride (0.0384 g, 0.216 mmol) and sodium chloride (0.0303 g, 0.518 mmol) in water (1.5 ml) was stirred and warm up to about 50ºC. The solution was allowed to cool down. A solution of triphenylphosphine (0.1280 g, 0.488 mmol) in ethanol (20 ml) was indeed prepared. The palladous chloride solution was added dropwise to the triphenylphosphine solution and stirred simultaneously. The resultant slurry was then warmed to about 50ºC over 30 proceeding to coagulate the precipitate. The mixture was cooled, filtered, and washed with water, acetone, and ether. The mathematical product was dried-out in a 50ºC oven for 3 minutes to lastly generate yellow solid palladium complex product (0.1302 g, 86%). 2.2The...If you want! to get a practiced essay, roam it on our website: BestEssayCheap.com

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