Dicyclopentadiene, drying

Novolacs are often modified through alkylations based on reactions with monomers other than, and in addition to, aldehydes during their manufacture. Examples might be inclusion of styrene, divinyl benzene, dicyclopentadiene, drying oils, or various alcohols. Despite significant production of all of these variants, most novolac volume is produced using phenol and formaldehyde. 

Dicyclopentadiene, drying of, 41, 97 Diethyl acetamidomalonate, 40, 21 Diethyl acetylenedicarboxylate as di-eneophile, 40, 86,87... 

Sulfur Polymer Cement. SPC has been proven effective in reducing leach rates of reactive heavy metals to the extent that some wastes can be managed solely as low level waste (LLW). When SPC is combined with mercury and lead oxides (both toxic metals), it interacts chemically to form mercury sulfide, HgS, and lead sulfide, PbS, both of which are insoluble in water. A dried sulfur residue from petroleum refining that contained 600-ppm vanadium (a carcinogen) was chemically modified using dicyclopentadiene and oligomer of cyclopentadiene and used to make SC (58). This material was examined by the California Department of Health Services (Cal EPA) and the leachable level of vanadium had been reduced to 8.3 ppm, well below the soluble threshold limit concentration of 24 ppm (59). 

Cyclopentadiene, b.p. 40°, is obtained by heating commercial 85% dicyclopentadiene (e.g., from Matheson, Coleman and Bell Company, Norwood, Ohio) under a short column (M in. diameter X 8-12 in. length) filled with glass helices. The distilled cyclopentadiene is collected in a receiver which is maintained at Dry Ice temperature until the cyclopentadiene is used. Methylcyclopentadiene and other substituted cyclopentadienes such as indene may also be employed for the synthesis of the correspondingly substituted ferrocenes. In these cases, the reaction of the hydrocarbon with sodium is much slower than with cyclopentadiene, and refluxing for several hours is required to complete the reaction. 

Cyclopentadiene was prepared2 by heating dicyclopentadiene (purchased from Eastman Organic Chemicals) and a pinch of hydro-quinone (1,4-benzenediol) under a column of glass helices or a Vigreux column at 175° and collecting the distillate in a receiver cooled with a 2-propanol-dry ice bath. The monomer was dried over Linde 4A Molecular Sieves at —20° and could be stored at this temperature for several weeks without excessive dimerization. 

A. Cyclopentadiene. Two hundred milliliters (195 g.) of technical dicyclopentadiene (Note 1) is placed in a 500-ml. twonecked round-bottomed flask equipped with thermometer and an upright Friedrichs-type condenser (through which water at 50° (Note 2) is circulated). The ground-glass (Note 3) outlet of the Friedrichs condenser is connected to the side arm of a simple distilling head fitted with a thermometer and attached to an efficient water-cooled condenser held in a vertical position. At the lower end of this condenser is a receiver which consists of a carefully weighed 500-ml. two-necked round-bottomed flask immersed in a Dry Ice bath (Note 4) and protected from the air by a calcium chloride drying tube. 

Cyclopentadiene dimerizes rapidly at room temperature and should be used immediately (Note 5) or stored at Dry Ice temperatures. As obtained above, the product has a refractive index of about 1.433 at 25° and is quite satisfactory as a starting material for the following preparation (Note 6). The yield, which is determined by weighing the receiving flask plus product, depends upon the quality of dicyclopentadiene employed (Note 7). 

Because cyclopentadiene is fixed in the. v-cis conformation, it is highly reactive in the Diels-Alder reaction. It is so reactive, in fact, that at room temperature, cyclopentadiene slowly reacts with itself to form dicyclopentadiene. Cyclopentadiene is regenerated by heating the dimer above 200 °C. At this temperature, the Diels-Alder reaction reverses, and the more volatile cyclopentadiene monomer distills over into a cold flask. The monomer can be stored indefinitely at dry-ice temperatures. 

In a l-l. three-necked flask equipped with a dropping funnel, a thermometer, and an efiicient fractionation column fitted with either a vapor- or liquid-splitting head (Note 1) is placed 400 ml. of mineral oil. The oil is heated to 240-270 and dicyclopen-tadiene (Note 2) is added at the rate of 5-10 ml. per minute. The reflux ratio and the rate of addition of dicyclopentadiene are adjusted to maintain the distillation head temperature at 40°. The cyclopentadiene is collected in a Dry Ice-acetone receiver (Note 3). 

A solution of 5/f-dibenzo[a,c]cycloheptene-5-one tosylhydrazone sodium salt (200 mg, 0.50 mmol) was photolyzed for 40 min at — 60 °C in dry THF (20 mL) containing freshly prepared cyclopentadiene monomer (5mL, 75 mmol). The mixture was allowed to warm to 5°C and the solvent was removed under reduced pressure. (The last trace of dicyclopentadiene was removed in vacuo). The residue was taken up in cyclohexane and column chromatographed on silica gel (cyclohexane) to give the product yield 94 mg (73%). Molecular distillation at 110°C/0.2 Torr yielded the product as a pure (GC) colorless liquid. 

A sulfur spray formulation containing sulfur, talc, Fiberglas, and dicyclopentadiene was successfully used to construct a block building. The dry-stacked cinder blocks were surface-bonded for structural stability by spraying with a thin coating of the molten formulation. The same formulation also formed an impervious lining on a dirt-formed pond. 

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