Methylcyclopentadiene dimer

The procedure for preparing the dry salt, K[C5H4(CH3)], is identical with that previously described in Sec. A for K[C5H5], except that methylcyclo-pentadiene (1.210 g, 15.1 mmol) is used in place of the 1,3-cyclopentadiene. Methylcyclopentadiene (isomer mixture) is obtained from the thermal cracking at 200° of commercially available methylcyclopentadiene dimer.4 The fraction distilling between 73 and 75° is collected at 0°. The distillate is then redistilled under nitrogen at atmospheric pressure, collected at 0°, and stored at — 78° in vacuo after degassing. 

Commercial methylcyclopentadiene dimer (Aldrich) is cracked using a 40-cm Vigreux column with a pot temperature of 210 to 225 °C. The first 10% of the distillate is discarded and 70% of the remainder is collected at 63 to 65°C at a drip rate of lOOmLh". The crude methylcyclopentadiene is redistilled using the same column to give a product containing 2% of CjHg impurity. 

Methylcyclopentadiene obtained by cracking the commercially available dimer contains up to 10% cyclopentadiene. This can lead to major purity problems with derived organometallic complexes, particularly for those compounds that contain several CH3C5H4 ligands. The diene can be purified simply by redistillation of the crude methylcyclopentadiene monomer. In our procedure the same fractional distillation apparatus is used for both the initial cracking and the redistillations. The purity of the methylcyclopentadiene can be assayed by H NMR spectroscopy. Methylcyclopentadiene can be stored at - 30 °C for a few days. 

Methyl cyclohexenyl ketone, 8 Methylcyclopentadiene, 200—201 Methylcyclopentadiene dimer, 200... 

Methylcyclopentadiene dimer results were identical to those for dicyclopentadiene at 120°C. Because of these results and the close structural similarity of the modifiers, further tests were discontinued with this modifier. 

This procedure requires S-6 days to complete. This procedure is the same as above except for the following changes. Reflux 90 mL (0.529 mol) of freshly cracked methylcyclopentadiene dimer with 20.0 g (0.870 mol) of sodium... 

The cyclopentadienide ion is alkylated by alkyl halides to give dimeric products [25] but by reaction with methyl iodide in liquid ammonia, methylcyclopentadienes have been obtained. [26]. In the gas-phase, however, the cyclopentadienide ion is a poor nucleophile [8]. ... 

Hydrocarbon Resins. About 50% of the DCPD produced is used in hydrocarbon resins. Crude DCPD with 60-75% purity is t5 ically used in this application. Other components in the feedstock may consist of codimers of CPD with isoprene, piperylene, and methylcyclopentadiene, and a small amoimt of the dimers of methylcyclopentadiene. Both DCPD and the codimers are incorporated into the hydrocarbon resins (46,47). Other C5 diolefins can also be added to the process. 

Methylcyclopentadiene readily undergoes reaction with metal carbonyls 47) and even 1,3-diphenylcyclopentadiene reacts with iron carbonyl 4S). A novel method for obtaining a ferrocene with one substituted ring, is the reaction of 1,3-diphenylcyclopentadiene with the dimer of cyclopentadienyl-iron dicarbonyl at 170° C to produce 1,3-diphenylferrocene in 15% yield. Other substituted cyclopentadienes which have been used are tetraphenyl-cyclopentadienone in the preparation of tetraphenyl(hydroxy)cyclopenta-dienylmanganese tricarbonyl 49) and indene in the preparation of the dimer of indenylmolybdenum tricarbonyl (50). A variety of substituted fulvenes have been used in the preparation of substituted cyclopentadienyl metal tricarbonyl compounds of Cr, Mo, and W (57, 52). This latter reaction proceeds best in the presence of a solvent, such as 1,2-dimethoxyethane, to permit easy abstraction of hydrogen. 

Meylemans HA, Quintana RL, Goldsmith BR, Harvey BG. Solvent-Free Conversion of Linalool to Methylcyclopentadiene Dimers A Route To Renewable High-Density Fuels. ChemSusChem. 2011 4(4) 465 69. 

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