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Abstract. Trans-1,2-dibromocyclohexane was prepared from synthesis reaction by reacting hydrogen peroxide and cyclohexene with hydrobromic acid. The yield was 2.72g (57.05%) of smoky white liquid product. Physical and characterization data indicated that the reaction afforded pure trans1,2-dibromocyclohexane solution. Introduction An Electrophilic Addition to an Alkene (Halogenation Reaction) is performed in this lab. Halogenation is a chemical reaction that involves the addition of one or more halogens to a compound or material. The percentile measurement of the halogenated process depends on the structural and functional characteristics of the organic matter, as well as on the specific halogen. The resulting product of the halogenated reaction is called halogenated compounds. The purposes of halogenated are to form a highly reactive intermediate, and to produce compounds with high application. The product yields that were obtained with decreasing initial reagent ratio for the reaction of cyclohexene at [Br2]: [cyclohexene] = 1:1 and 2:1. Cyclohexene is the most stable alkene. Therefore, only the dibromide yields could be determined by GC.5 Another method for the synthesis is Heterocyclic Synthesis (Hassner Reaction), which is some or all the atoms in their molecules are bound in rings containing at least one atom of non-carbon element (C).4 Reaction Scheme

Mechanism

Results and Discussion. Hydrobromic acid was reacted with hydrogen peroxide and cyclohexene to produce Trans-1,2dibromocyclohexane. After a drop of hydrogen peroxide, the color of solution was yellow at first, then it turned red as more added, and it fogged up. After a drop of cyclohexene, the solution fogged up, then it turned red and there was black color at the bottom. For the extraction part, after adding 30ml of DCM, the bottom layer was orangey red, and the top layer was yellow. After adding 10ml of sodium bisulfite, the bottom layer was foggy white, and the top layer was clear. After the reaction was complete, the weight of the product was 2.72g. By determining the refractive index for correct temperature, the temperature of an instrument was 24.5oC, and refractive index was 1.537. Therefore, the correct RI was 1.539, which is trans1,2-dibromocyclohexene. Cyclohexene was limiting reactant. The yield was 2.72g (57.05%) of liquid product.

The GC chromatogram data indicated that the product was pure and showed a peak for trans-1,2dibromocyclohexene with a retention time of 6.108 min. The MS spectrum showed the molecular ion (M+, m/Z 242) and various fragments consistent with the structure of trans-1,2dibromocyclohexene. GC retention time of trans-1,2-dibromocyclohexane was 6.110 min; (81,100), (79,20), (161,10), (163,10). GC retention time of cis-2-bromocyclohexanol was 5.414 mins; (81,100), (79,10), (99, 30), (179,5). There were two observations that might explain the modest yield: 1) the crude product wasn’t stirred well enough and 2) the extraction method didn’t separate the compound well enough. Experimental General methods: The Reaction was carried out under atmospheric conditions using commercially available reagents and solvents. RI measurement was analyzed by thermo fisher refractive index. The product was analyzed by Shimadzu QP-2010 Gas Chromatography Mass Spectrometry. Trans-1,2-dibromocyclohexane. The triangular spin vane and 4.5 mL of hydrobromic acid 48% (w/w% = 48g/100g) were added to 25 mL round bottom flask (RBF). Setting up a hot plate, then place the RBF inside can filled with ice on the top of the hot plate. 2.1 mL of hydrogen peroxide 30% solution dropwise was added to the HBr in the flask. Adding one drop at a time, slowly, then then let the reaction stirred for 15 mins. The color of solution was yellow at first, then it turned red as more added, and it fogged up. 2.0 mL of cyclohexene solution dropwise was added to the HBr in the flask. Adding one drop at a time, slowly, then then let the reaction stirred for 15 mins. The solution fogged up, then it turned red and there was black color at the bottom. Then extraction was used to separate a compound from a mixture. The weight of the product was 2.72,

and the %yield was 57.05%. Trans-1,2-dibromocyclohexane was collected, got tested with correct refractive index and chromatogram methods. GC retention time of trans-1,2dibromocyclohexane was 6.110 min; (81,100), (79,20), (161,10), (163,10). GC retention time of cis-2-bromocyclohexanol was 5.414 mins; (81,100), (79,10), (99, 30), (179,5)....