Molecular distillation receivers

The relative weights of the two components of the vapour phase will be idaitical with the relative weights in the distillate, i.e., the weights of the two liquids collecting in the receiver are directly proportional to their vapour pressures and their molecular weights. 

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. 

Materials. Deionized-distilled water was used for all syntheses and distilled water was used in all solutions. All salts were reagent grade and were used as received. Dialysis membrane was Spectrapor no. 2, 12,000 upper molecular-weight-cutoff membrane from Spectrum Medical Industries, Los Angeles, CA. 

Trimethylsilyl)acetylene was used as received from Aldrich Chemical Company, Inc. N,N-Diisopropylethylamine was distilled from calcium hydride (atmospheric pressure) and stored over 4 A molecular sieves under argon. 

Haas) and I(-( hydroxymethyl)acrylamlde (IJ-methylol acrylamide, American Cyanamld) were used without purification. Acetonitrile was dried over molecular sieves (4A) and distilled prior to use. Ethanolamlne and l-amlno-2-propanol were vacuum distilled. Reagent grade acryloyl chloride, 2-propanol, and sodium persulfate were used as received. 

Anhydrous t-butyl alcohol may be conveniently prepared by distilling it from calcium hydride into a receiver containing Type 4A molecular sieves. 

Poly(ethyl methacrylate) (Cellomer Associates) was vacuum dried at 50 C. The molecular weight (M ) was determined to be 3.3 X 10 from its intrinsic viscosity in ethyl acetate.— Chloroform (spectral grade) and deuterochloroform (MSD Isotopes) were used as received. Prior to sample preparation the solvent was degassed using five freeze-thaw cycles. The solvent was vacuum distilled onto the polymer In a 12 nm NMR tube, and sealed. 

Raw Materials. The raw materials used in this study are shown in Table l. The isocyanatoethyl methacrylate (lEM) was distilled before use. The solvent was dried by a 4A molecular sieve overnight before use. The other materials were used as received. 

Reagent grade tetrahydrofuran was purchased from Fisher Scientific Company and either freshly distilled from sodium metal and benzophenone or dried at least 3 days over activated Linde 4 A molecular sieves before use in reaction A. It was used as received for reaction C. 

The residue from distillation is a viscous oil consisting of high-molecular-weight compounds. Further cyclic oligomers, especially trimer and tetramer, can be obtained by heating this oil to about 400°C.To do this, a new receiver is fitted to the distillation apparatus and the flask heated to 400-450°C.The more volatile products are carried over in a slow stream of nitrogen and the distillate is then fractionated as before. 

Bromo-2-naphthoic add (1, 98%, Sigma Chemical Co.), 3.5-dimethylphenol (2, >98%, Merck-Schuchard), 1,3-dicyclohexylcarbodiimide (DCC, 99%, Merck-Schuchard), and 4-(dimethylamino)pyridine (DMAP, 99%, Aldrich Chemical Co., Inc.) were used as received. Dichloromethane was distilled from phosphorus pentoxide and stored over activated molecular sieves (4A). 

This solvent is fairly pure as received. The only impurities are water and traces of dimethyl sulfide. Dimethyl sulfide can be removed by a preliminary vacuum distillation, or by bubbling an inert gas through the solution for 10 to 20 min before use. The water content can be reduced to 10 ppm by sequential treatment with two batches of 3 A molecular sieves (activation of the sieve at 500°C for 16 h in an inert atmosphere has been advocated [62], but activation for 15 h at 300°C should suffice [52]). Calcium hydride and a number of other basic reagents have been advocated as drying agents, but in fact all of these are ineffective [32]. Tetrabutylammonium hexafluorophosphate exhibits good solubility in THF. 

Spc troscopic-gtade QHe purchased from Dojindo Laboratories was dried with Molecular Sieves 4A and distilled under a reduced pressure. Dichloromethane-d2 (99.95% up D) obtained from Aldrich Chemical Co., Inc., and benzene-d (99.6% up D) from Wako Pure Chemical Industries, Ltd., were used as received. The molalities of the samples are listed in Table 1. The amount concentrations of the complex solutions were calculated at each temperature from the molalities and the partial molar volumes of the components at infinite dilution. For the CH2Q2 and C6H6 solutions, all the relevant partial molar volumes are available. For the CeD solutions, the partial molar volume of the sdute was assum to be the same as that in CeHe. For the CD2CI2 soluticms, the partial molar volume of the solvent was replaced by that of CH2CI2 and the partial molar volume of the scdute by that in CH2O2. 

Cyclohexane was dried by distillation from calcium hydride and stored over 4A molecular sieves. Unless stated otherwise, all solvents and reagents in this procedure were obtained commercially and used as received. 

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