Sublimation yield from

The corresponding tellurium diimide BuNTe( -N Bu)2TeN Bu (10.7) may be obtained in good yields from the reaction of lithium tert-butylamide with TeCU in THE (Eq. 10.3). °" In toluene solution this reaction also produces the cyclic tellurium(II) imide (TcN Bu)3. The dimer 10.7 is obtained as an orange solid, which can be purified by vacuum sublimation at ca. 90°C. 

It may be purified by recrystallization from hot hydrochloric add, as recommended in Org. Syn. 3, 87, but on account of the difficulty of filtration this procedure is satisfactory on a small scale only. It is preferably distilled in 200-g. lots from a 500-cc. Claisen flask under 10-15 mm. pressure, b.p. 160-165V12 mm. It is important that no air inlet be used to prevent bumping, since under these conditions it partly sublimes and causes trouble by stopping up the connections. A filter or distilling flask is used as a receiver and only a short but wide bore (10 mm.) air condenser is necessary. This product is pale yellow and melts at 95-96°. The yield from 200 g. of crude product is 180-185 g-... 

For comparison, Battles et al. (15) determined the partial heats of sublimation of Pu02(g) and Pu0(g) above PuOi.33 over the temperature range 1937 to 2342 K by means of mass spectrometric measurements with Iridium effusion cells. The absence of Iridium oxides or Iridium species In the vapor phase Indicated that Iridium was nonreducing toward plutonia. The partial heats of sublimation calculated from the slopes of the temperature dependency data yielded values of 127.1 1.2 and 138.8 1.6 kcal/mol for Pu0(g) and Pu02(g) ... 

When the decomposition of N-phenyl-1,3,4,6-tetrahydrothieno-(3,4-c)-pyrrole-2,2-dioxide (II) was carried out in a sublimator a relatively high yield (80-95%) was obtained. However, under identical conditions, the decomposition of 5-(carboethoxyphenyl)-l,3,4,6-tetrahydrothieno(3,4-c)-pyrrole-2,2-dioxide yielded only 15% of diene product. This observation was found in agreement with the results reported by Alston (18). It was suggested that the yield from these sulfones depended on the relative volatility of the exocyclic diene formed since these dienes could undergo dimerization readily at the decomposition temperature of lbO C. 

The product yield from an entrainer-sublimation process may be estimated as follows. The mass flowrate G of the inert gas and the mass sublimation rate S are related by ... 

The theoretical maximum yield from an entrainer sublimation process is the difference between the calculated sublimation rates corresponding to the conditions in the vaporisation and condensation stages. 

S. C. Spalding Concerning the necessarily simple product spectrum from the chlorination, I would comment that the physical evidence on yields from the run at 500°C. would seem to preclude the possible formation of a structurally simple product. It seemed that about one-third of the coal appeared as an oil. Some white solid substance sublimed out of the reaction zone and precipitated in the cooler zones. 

High-quality albuterol was obtained in good yield from this process. However, several environmental disadvantages were identified. The preparation of the keto aldehyde hydrate (KAH) generated dimethyl sulfide, methyl bromide, and trimethyl-sulfonium bromide (this compound sublimed in the condenser). In addition, reduction of the Schiff base with dimethylsulfide borane, although very attractive in simplifying... 

Carbon selenide telluride is a thermally very unstable compound that cannot be sublimed in a high vacuum. The compound was claimed to have been obtained in 8% yield from carbon monoselenide, generated from carbon diselenide in a high frequency discharge, and gaseous tellurium. The infrared spectrum of carbon selenide telluride was recorded. No details about the reaction conditions were reported1. 

Dimetbyl-l, 2-tellurazole1 1.7 g (15 mmol) of hydroxylamine O-sulfonic acid are dissolved in 5 ml of water, the solution is cooled to 0°, and 1.23 g (15 mmol) of methyl propynyl ketone are added to the vigorously stirred solution under nitrogen. The solution is stirred for 35 min and 2.5 g (30 mmol) of sodium acetate and 25 ml (l 5 mmol) of a 0.6 molar aqueous solution of potassium telluride are added to the solution over 20 min. The resultant solution is allowed to warm to 20 and is then stirred for 4 h. The reaction mixture is extracted 4 times with 20 ml portions of ethyl acetate and the extract is dried with anhydrous sodium sulfate, filtered, and evaporated to dryness. The residue is sublimed at 70°/0.001 torr and the sublimate recrystallized from acetone yield 0.3 mmol (10%) m.p. 111 . 

The colorless zinc compound, Zn(CisH6)2, which sublimes at 160° under partial decomposition, is obtained in small yield from zinc chloride and cyclopentadienyl sodium in diethyl ether however, the less stable cadmium compound decomposes, with separation of cadmium, under these conditions (55). The mercury compound, Hg(CsH5)2, is produced in 20% yield by the action of the sodium derivative on mercuric chloride in tetrahydrofuran (215). The action of cyclopentadiene on the complex K2(HgI ) in aqueous alkaline solution results in the precipitation of a mixture of CsHsHgl and Hg(CsH6)2, from which the latter compound may be obtained in good yield by extraction with a mixture of tetrahydrofuran and petroleum ether (62). It forms pale yellow crystals which begin to decompose at about 60° and which melt at 83-85°. The compound is readily soluble in most solvents it decomposes slowly even when kept in the dark at room temperature it is insoluble in water and reacts with neither water nor bases. On the other hand, decomposition occurs in dilute hydrochloric acid. It converts ferric chloride to ferrocene quantitatively, and it yields an adduct with maleic anhydride (215). 

A better synthesis (89% yield) of Fe(CO)3(PPh3)2 is reported from [PPN]2[Fe4(CO)i3], where PPN+ = bis(triphenylphosphine)iminium. The C0X2 (X = Cl, Br, I) catalyzed substitution of CO in Fe(CO)j is reported to yield Fe(CO)4L species in 15 to 99% yield and Fe(CO)3(PPh3)2 was prepared (net 62% yield) from Fe(CO)s in a two-step procedure that requires a chromatographic separation. Strohmeier and Muller report that irradiation of Fe(CO)s in the presence of several phosphines produces Fe(CO)3L2 and Fe(CO)4L complexes in yields that range from 13% for the synthesis of Fe(CO)3[P(/i-Bu)3]2 to 35% for Fe(CO)3[P(c-C6Hn)3]2. For some of the compounds synthesized, vacuum sublimation is necessary to separate the Fe(CO)3L2 species from Fe(CO)4L. The one-step photochemical procedure we report here employs cyclohexane as a solvent. That enables unreacted phosphine, Fe(CO)s, and Fe(CO)4L to remain in solution while pure Fe(CO)3L2 precipitates. It is essential that the phosphines used in these reactions be free of phosphine oxides, which labilize CO and yield products other than Fe(CO)3(PR3)2 complexes. 

The oligothiophene films were prepared by solution cast methods and by vacuum deposition. Depending on the cast procedure, different layer thicknesses could be achieved. Preparation from solution either by drop casting or spincoating resulted in films ranging from 50 nm to 200 nm in thickness. Vacuum sublimation yielded very thin layers in the range of 10 nm to 15 nm, which nevertheless allowed to build-up and operate an OFET structure of molecular thickness as demonstrated in this chapter. 

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