Synthesis and Chemistry of Alkenes
Essay by blueice • February 18, 2016 • Lab Report • 752 Words (4 Pages) • 1,668 Views
Synthesis and Chemistry of Alkenes
Abstract
To carry out the dehydration reaction of 4-methyl-2-pentanol and analyze the alkene product by gas chromatography. Later, chemical tests of Bromine, Baeyer and chromic acid on 4-methyl-2-pentanol and the product mixture is done.
Equations
Procedure Reference
Marrs, P. Chemistry 323 Organic Chemistry Laboratory Manual, Spring 2016, 17-22, B19
Dehydration of 4-Methyl-2-pentanol
Table1: Reagents used in dehydration of 4-methyl-2-pentanol
Compound | MW | Used | Millimoles | Physical and Safety Data |
4-methyl-2-pentanol C6H4O | 102.17 | 5.001g | 48.95 | Hazardous in case of eye contact. Irritant d. 807.50kg/m2 |
85%Phosphoric acid H3PO4 | 98.00 | 5mL | 72.9 | Corrosive, wear protective clothing, gloves & eye protection. 85% by weight in H2O. d 1.68 g/mL. |
The limiting reagent is: 4-methyl-2pentanol
Table2: Product formed after the dehydration of 4-methyl-2-pentanol
Compound | MW | Isolated | moles | % yield |
4-methyl-2-pentene C6H12 (Alkene Product from the GC table) | 84.16g/mol | 2.055g | 0.0244 | 49.89 |
Observations:
My isolated product was clear. I did spill my alkene product during the chemical tests but I was able to weigh it properly calculate the % yield. However my sample I turned in will have significantly less than what is reported due to the spill.
Sample Calculations:
4-methyl-2-pentanol (millimoles) = mass used / molecular weight
= (5.001g) / (102.174g/mol)
= 0.04895 moles * (1000millimoles/1mole) = 48.95milimoles
85% phosphoric acid (millimoles) = (volume x density x percentage) / molecular weight
= (5mL x 1.68 g/mL x 0.85) / (98.0 g/mol)
= 0.07285moles * (1000millimoles/1mole) = 72.9millimoles
% yield based on limiting reagent:
Actual moles of 2-methyl-2-pentene = mass isolated / molecular weight
= (2.0551g) / (84.16g/mol)
= 0.02442moles *(1000millimoles/1mole) = 24.42 millimoles
Percent (%) Yield of 4-methyl-2pentanol
= (actual moles) / (expected moles) x 100%
= (24.42 millimoles) / (48.95) x 100% = 49.89%
Table 3: Results of the Gas Chromatographic Analysis
Component | Retention Time | % Composition (assume equal to % area) |
2-methyl-2-pentene (My own Graph) | 2.804 | 1.09 |
4-methyl-1-pentene (Graph Provided) | 2.482 | 6.70 |
4-methyl-2-pentene (Graph Provided) | 2.543 | 54.70 |
2-methyl-1-pentene (Graph Provided) | 2.652 | 6.05 |
2-methyl-2-pentene (Graph Provided) | 2.774 | 27.92 |
3-methyl-2-pentene (Graph Provided) | 2.880 | 3.54 |
The GC analysis sheets are attached at the end of the report.
Table 4: Functional Group Tests
Unknown | Bromine Test | Baeyer Test | Chromic Acid test | Identity |
A | Orange (-) | Purple(-) | Yellow (-) | Toluene |
B | Colourless(+) | Brown(+) | Yellow(-) | Styrene |
C | Orange(-) | Purple(-) | Green(+) | Benzly alcohol |
D | Colourless(+) | Brown(+) | Green(+) | Cinnamyl alcohol |
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