Synthesis and Handling Properties
The first reported synthesis of ferrocene used the Grignard reagent cyclopentadienyl magnesium bromide, which can be prepared by reacting cyclopentadiene with magnesium and bromoethane in anhydrous benzene. Iron(II) chloride is then suspended in anhydrous diethyl ether and added to the Grignard reagent. The reaction sequence is:
- 2 C5H5MgBr + FeCl2 → Fe(C5H5)2 + MgCl2 + MgBr2
Numerous other syntheses have been reported, including the direct reaction of gas-phase cyclopentadiene with metallic iron at 350 °C or with iron pentacarbonyl.
- Fe + 2 C5H6(g) → Fe(C5H5)2 + H2(g)
- Fe(CO)5 + 2 C5H6(g) → Fe(C5H5)2 + 5 CO(g) + H2(g)
More efficient preparative methods are generally a modification of the original transmetalation sequence using either commercially available sodium cyclopentadienide or freshly cracked cyclopentadiene and potassium hydroxide with anhydrous iron(II) chloride in ethereal solvents:
- 2 NaC5H5 + FeCl2 → Fe(C5H5)2 + 2 NaCl
- FeCl2.4H2O + 2 C5H6 + 2 KOH → Fe(C5H5)2 + 2 KCl + 6 H2O
Direct transmetalation can also be used to prepare ferrocene from other metallocenes, such as manganocene:
- FeCl2 + Mn(C5H5)2 → MnCl2 + Fe(C5H5)2
As expected for a symmetric and uncharged species, ferrocene is soluble in normal organic solvents, such as benzene, but is insoluble in water. Ferrocene is an air-stable orange solid that readily sublimes, especially upon heating in a vacuum. It is stable to temperatures as high as 400 °C. The following table gives typical values of vapor pressure of ferrocene at different temperatures:
| Pressure (Pa) | 1 | 10 | 100 |
|---|---|---|---|
| Temperature (K) | 298 | 323 | 353 |
Read more about this topic: Ferrocene
Famous quotes containing the words synthesis, handling and/or properties:
“It is in this impossibility of attaining to a synthesis of the inner life and the outward that the inferiority of the biographer to the novelist lies. The biographer quite clearly sees Peel, say, seated on his bench while his opponents overwhelm him with perhaps undeserved censure. He sees him motionless, miserable, his head bent on his breast. He asks himself: “What is he thinking?” and he knows nothing.”
—Andre Maurois (1885–1967)
“That a good fit between parental handling and child temperament is vital to help children adapt to the imperatives of their society is a crucial concept that can be applied to other cultures.”
—Stella Chess (20th century)
“The reason why men enter into society, is the preservation of their property; and the end why they choose and authorize a legislative, is, that there may be laws made, and rules set, as guards and fences to the properties of all the members of the society: to limit the power, and moderate the dominion, of every part and member of the society.”
—John Locke (1632–1704)