Creased flask

The apparatus consists of a 3-1. three-necked round-bottomed creased flask, with standard ball joints and an indented cone-shaped bottom (Note 1), which is heated by means of an electric mantle and is equipped with a high-speecT stirrer of stainless steel driven by a 10,000 r.p.m. motor (Note 2). One side neck is fitted with a bulb-type air-cooled condenser (Note 3), on top of which fits a 1-1. pressure-equalizing Hershberg dropping funnel (Note 4). The top of the dropping funnel is to be connected in turn to a U-tube containing a 1-cm. head of mercury. The entire apparatus is securely fastened to a sturdy support. 

This preparation has also been carried out on a 1.0 mole scale by the checkers, using a 5-1. creased flask. Comparable yields are obtainable. 

This reaction may be carried out under pressure in a rocking autoclave at 180° in about 8 hours. When it is carried out under reflux with vigorous stirring in a creased flask it is complete in about 20 hours, whereas 50-60 hours are required if an ordinary flask is used. 

Connect a dry 100-ml Morton creased flask with a three-necked opening to a septum, condenser, and thermometer. Add a glass-encased magnetic stirring bar. 

Coupling, of diazotized Ji-aminoaceto-phenone with quinone, 34, 1 of diazotized 3,5-dichloro-2-aminoben-zoic acid to give 4,4, 6,6 -tetra-chlorodiphenic acid, 31, 96 of dibromomalononitrile to tetracyanoethylene, 39, 65 of diphenyldichloromethane to tetra-phenylethylene, 31,104 Creased flask, 37, 55 Creosol, 33,17 Crotonaldehyde, 33, 15 34, 29 diethyl acetal, 32, 5 reaction with ethynylmagnesium bromide, 39, 57... 

A solution of chloromethyl l,l,l,3,3,3-hexafluoro-2-propyl ether (754 g, 3.49 moles) in dry tetrahydrothiophene 1,1-dioxide (203 g, 3,49 moles) were stirred and heated to 130°C in a creased flask fitted with a fractional distillation assembly. A distillate (200 ml), b748 56.0° to 62°C, was collected during 5 h. Then the reaction mixture was cooled to room temperature, dry potassium fluoride (100 g, 1.74 moles) was added, and the cycle of operations was repeated 3 times at temperatures between 138° to 185°C to give distillates (100 ml, 100 ml and 50 ml), b746 58° to 61°C, 55.5° to 57°C, and 54.2° to 55.9°C, respectively. From this portionwise addition of potassium fluoride (503 g, 8.7 moles) there was obtained distillates totalling 672 g, b746 54.2° to 62.0°C, which by GLC analysis was about 92% fluoromethyl and 6.8% chloromethyl l,l,l,3,3,3-hexafluoro-2-propyl ether. 

The macrocyclization step involving the two bifunctional compounds 2 and 3 is performed under high-dilution conditions. For this reaction there is a need to use a specially adapted apparatus illustrated in Fig. 5.3. The crucial features of this reaction are the precision addition funnels which have to deliver the solutions at a low and constant rate and the vigorous stirring ensured by a high-speed motor and by the creased flask. 

The preparation is conveniently carried out in a SOO-mL creased flask fitted with a paddle stirrer or, alternatively, in a blender. Smaller scale preparations may be conducted in an Erlenmeyer flask using a magnetic stirrer. Because PdClj is only sparingly soluble in water, the mixture is heterogeneous and the amount of time required for completion of the reaction varies with efficiency of stirring. 

For example, n-pentylsodium may be prepared in 80-90% yield by reaction between Na sand (25 jxra particle size) and 1-chloropentane in n-pentane at — 10°C in a creased flask equipped with a high-speed stirrer. Comparable 3delds of n-pentylsodium may be obtained in n-heptane, in which the yield of organoalkali decreases only from 85 to 75% after storage at RT for 24 days. In contrast, in n-BujO the yield of n-pentylsodium is 63%, but after 10 days most of the reagent has decomposed by reaction with the solvent. In 1,2-dimethoxyethane (DME) and 12 the yields of n-pentylsodium are < 15 %. Even under inert solvents samples of n-pentylsodium must be prepared and stored at RT or lower because pyrolysis is appreciable at 50°C and rapid at 100°C. 

BuOK (84 g, 0.75 mol) was added to DMSO (400 mL) in a creased flask fitted with stirrer and condenser. l,l-Dichloro-2-ethyl-3-methylcyclopropane(2, 38 g, 0.25 mol) was added dropwise at 25"C under N2 (external cooling). After 2 h, the product was isolated by addition to ice-water, pentane extraction, drying (Na2S04) and removal of pentane at 25"C yield 62% (determined by GC). 

The cooled dispersion is either poured from the creased flask into a suitable container for further use or utilized directly in the dispersion flask (sodium hydride, synthesis 3). 

Equipment Cleanup. If the dispersion is removed from the creased flask, the equipment should be decontaminated as soon as possible. Approximately 150 ml. of kerosine or similar hydrocarbon is added to the now-empty flask and swirled around to wash the residual sodium from the walls. A solution of 30 ml. of isopropyl alcohol in 100 ml. of kerosine is slowly added to the flask and permitted to react with the sodium residue. Similarly, the stirrer blade and shaft, seal, thermometer, and condenser are decontaminated by washing in a 25% solution of isopropyl alcohol in kerosine. 

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