Sodium, toluene dispersion

Sodium metaperiodate [Metapenodic acid, sodium salt], 55, 68 Sodium, toluene dispersion of, 55, 65 Spiro[cyclopentane-l,l -indene], 55, 94 CE) Stilbene [Benzene, 1,1 (1,2-ethenediyl)-bis-], 55,115... 

Sodium toluene dispersion of, 55, 65 Sodium p-toluenesulfinate, 57, 103 Spiro[4 n] alkenones, 58, 62 Spiro[cyclopentane-l,l -indene] 55, 94 Squalene, 56, 116 Squalene, 2,3-epoxy, 56, 116 Stannic chloride, 56, 97 Steroids synthesis, 58, 85 E Stilbene, 55, 115,58, 73 z-Stilbene, 58, 133 Styrene, 56, 35,58, 43 Styrene glycol, 55, 116 Styrene glycol dimesylate, 55, 116 Succinic acid, 58, 85 Succinic anhydride, 58, 85 Sucunimide, 56, 50, 58, 126 Succimmide, Vbromo, 55, 28, 56, 49 SULFIDE CONTRACTION, 55, 127 Sulfide, dimethyl-, 56, 37 SULFIDE SYNTHESIS, 58, 143,58, 138 SULFIDE SYNTHESIS ALKYL ARYL SULFIDES, 58, 143 SULFIDE SYNTHFSIS DIALKYL SULFIDES, 58, 143 SULFIDE SYNTHESIS UNSYMMETRI-CAL DIALKYL DISULFIDES, 58, 147 SULFONYL CYANIDES, 57, 88 Sulfur tetrafluoride, 57, 51... 

Toluene is commonly used. It can be dried by molecular sieves or direct distillation from calcium hydride into the reaction flask. Solvent stored over calcium hydride for several days is usually sufficiently dry to decant directly into the reaction flask, but distillation gives more consistent results. Any solvent with a boiling point sufficiently high to melt sodium is satisfactory. The submitters have also used methyl-cyclohexane and xylene in acyloin condensations. After the sodium is dispersed, the high-boiling solvent can be removed and replaced with anhydrous ether (as noted by the submitters) or can be retained and used in combination with ether (checkers). 

A 5-ml. portion of dry toluene is introduced into the dask with a syringe, and sodium hydride dispersion is stirred for 1 minute. Then 4 ml. of the supernatant toluene is carefully removed from the dask with a syringe. 

Colloidal potassium has recently been proved as a more active reducer than the same metal that has been conventionally powdered by means of shaking it in hot octane (Luche et al. 1984 Chou You 1987 Wang et al. 1994). In order to prepare colloidal potassium, a piece of this metal in dry toluene or xylene under an argon atmosphere is submitted to ultrasonic irradiation at ca. 10°C. A silvery blue color is rapidly developed, and in a few minutes the metal disappears. A common cleaning bath (e.g., Sonoclean, 35 kHz) filled with water and crushed ice can be used. A very fine suspension of potassium is thus obtained that settles very slowly on standing. In THF, the same method did not work. Attempts to disperse lithium in THF or toluene or xylene were unsuccessful, whereas sodium was dispersed in xylene but not in THF or toluene (Luche et al. 1984). Ultrasonic waves interact with the metal via their cavitational effects (see Section 5.2.4). These effects are closely related to the physical constants of the medium, such as vapor pressure, viscosity, and sur-... 

The suspension of sodium is best prepared as follows. In a three-necked flask fitted with a ground-glass stopper, a reflux condenser, and a Vibromischer (available from A. G. fur Chemie-Apparatebau, Zurich, Switzerland) are placed 150 ml. of toluene and 23 g. of sodium. When the toluene is boiling under reflux, the melted sodium is dispersed by the Vibromischer, and the flask is quickly cooled. Under nitrogen atmosphere the toluene is removed by decantation and is replaced by 350 ml. of dry tetra-hydrofuran. 

Sodium is commonly shipped in 36- to 70-t tank cars in the United States. Smaller amounts are shipped in 16-t tank tmcks or ISO-tanks. Sodium is also available in 104- and 190-kg dmms, and in bricks (0.5—5 kg). A thin layer of oxide, hydroxide, or carbonate is usually present. Sodium is also marketed in small lots as a dispersion in an inert hydrocarbon, or produced in-process via high pressure injection into a pumped stream of inert carrier fluid, such as toluene or mineral oil. 

The finely divided sodium was prepared under boiling toluene or boiling xylene by agitation of the molten sodium with a Vibromixer. After the dispersion had cooled and the sodium had settled, the toluene or xylene was decanted and the finely divided sodium was washed with two portions of anhydrous ether. 

Our initial studies (23) were performed in toluene, and Table I shows the results from the polymerization of a number of representative monomers. The data reported in Table I are for direct addition of the monomer to the sodium dispersion. Inverse addition often leads to higher molecular weights, although the overall polymer yields are usually lower (15,23). The results in Table I show that, under these reaction conditions, a bimodal molecular molecular weight distribution is normally obtained. Furthermore, it is obvious that the crude polymer yields drop precipitously as the steric hindrance in the monomer increases. 

Phenylmethyldichlorosilane (Petrarch) was distilled prior to use and dried over CaH2- Toluene was distilled from CaH2 and dried over CaH2- The known amounts of sodium were placed in a flask filled with toluene and purged with dry argon. This flask was placed in the ultrasonic bath (75-1970 Ultramet II Sonic Cleaner, Buehler Ltd.) until stable dispersion of sodium was formed. In some experiments an immersion-type ultrasonic... 

Polydiorganosilane copolymers were synthesized by adding 2.2 moles of a sodium dispersion in a light oil (Aldrich) at a constant rate (320 meq/min) into a toluene solution which contained a total of 1 mole of diorganodichlorsilane monomers. 

The first stage of a reaction involved the addition of sodium dispersed in toluene to a solution of adipic ester in toluene. The subsequent addition of iodomethane (b.p. 42°C) was too fast and vigorous boiling ejected some of the flask contents. Exposure of sodium particles to air caused ignition, and a violent toluene-air explosion followed [ 1 ]. When a reagent as volatile and reactive as iodomethane is added to a hot reaction mixture, controlled addition, and one or more wide-bore reflux condensers are essential. A similar incident involving benzene was also reported [2]. 

In the preparation of triphenylphosphine from chlorobenzene, phosphorus trichloride and sodium dispersed in toluene or xylene, the possibility of explosion is avoided by adding about 1 mol% of a lower alcohol, based on sodium usage. 

After storage for 16 years in a tin, a sealed bottle originally holding sodium dispersed in xylene was found to contain a yellow/white solid layer in place of the expected supernatant xylene. Scraping the solid out caused a violent explosion. The force of the explosion leads to a suspicion of peroxide formation, but there is no obvious explanation. Reactive materials like alkali-metal dispersions in volatile solvents should not be stored indefinitely, but clearly labeled after receipt or preparation to show the disposal date. Disposal of such dispersions by binning is recommended. Sodium dispersed in toluene might behave in the same way. 

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