1 The experiment includes contributions from past instructors, course textbooks, and others affiliated with course 5.310 (Updated by John Dolhun May 2017).
2 Adapted from: Keneth L. Williamson, “Macroscale and Microscale Organic Experiments”, 2nd Edition; D. C. Heat and Company, Lexington, MA, 1994.
3 At room temperature, cyclopentadiene is 8% dimerized in 4 h and 50% dimerized in 24 h.
4 Adapted from: Keneth L. Williamson, “Macroscale and Microscale Organic Experiments”, 2nd Edition; D. C. Heat and Company, Lexington, MA, 1994.
5 Potassium hydroxide is ground into a fine powder by employing an ordinary food blender.
6 The anion of cyclopentadiene rapidly decomposes in air, and iron (II) chloride although reasonable stable in solid state is readily oxidized to the iron (III) (ferric) state in solution.
7 The mixture of cyclopentadiene monomer and potassium hydroxide slurry should appear pink but may turn either dark green or black. This dark coloration is due to oxidation of small amounts of the cyclopentadiene anion and is not detrimental to this particular procedure. Pure cyclopentadiene solutions are colorless. In other organometallic preparations more scrupulous efforts to eliminate oxygen must be followed.
8 Among simple hydrocarbons, cyclopentadiene is relatively acidic: pKa=15.5
9 Acetone* may generally be used to clean glassware during this synthesis. A concentrated solution of KOH in water may be used to clean the petri dishes after sublimation.
10 P.J. Graham, R.V. Lindsey, G.W. Parshall, M.L. Peterson, and G.M. Whitman, J. Amer. Chem. Soc. 1957, 79, 3416.
11 M. Rosenblum and R.B. Woodward, J. Amer. Chem. Soc. 1958, 80, 5443.
12 R.B. Woodward, M. Rosenblum, and M.C. Whiting, J. Amer. Chem. Soc. 1952, 74, 3458.
The following references are relevant to the preparation and properties of ferrocene and related metallocenes.
- Wilkinson, G. The Iron Sandwich. A Recollection of the First Four Months, J. Organomet. Chem. 1975, 100, 273.
- Birmingham, J. "Synthesis of Cyclopentadiene Metal Compounds," Adv. Organometallic Chem. 1965, 2, 365.
- Coates, G. E.; Greene, M. L. H.; Wade, K. Organometallic Compounds, vol. 2, Methuen and Co., London, 1968, pp 90-115.
- Jolly, W. L. Inorg. Synth., 1968, 11, 120
- Cotton, F. A.; Wilkinson, G. Advanced Inorganic Chemistry, 5th Ed., Wiley: New York, 1988, p. 736.
- M. Rosenbum, M. Chemistry of the Iron Group Metallocenes, Part one, John Wiley and Sons, Inc., New York, 1965.
- King, R. B. Transition Metal Organometallic Chemistry: An Introduction, Academic Press: New York, 1965.