Distillation under inert atmosphere

If the distillation is being used to dry a reagent, the process must be carried out under an inert atmosphere. The following procedure can be used  

Dry all the glass apparatus in an oven, or with a heat gun under vacuum, and purge with inert gas whilst cooling. This is most easily accomplished by connecting the apparatus to a double manifold/bubbler system (see Chapter 4). Although Quickfit distillation assemblies can be used, we prefer one piece type apparatus, as shown in Figs. 11.8 and 11.9b. 

When the glassware has cooled, increase the inert gas flow, quickly disconnect the distillation flask, add any drying agent required, a few anti-bumping granules and the liquid to be distilled, then reassemble the system. 

Heat the distillation flask in an oil bath (do not carry out distillations using a heating mantle) and collect the distillate which comes over at the required temperature. 

When the distillation is complete remove the collector and seal it quickly with a septum. Most reagents can simply be poured into a reagent bottle before sealing, provided you are quick. However, if the reagent is particularly sensitive to air or moisture a cannulation 

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An apparatus for distillation under inert atmosphere, illustrated in Fig. 1.3, incorporates the same features seen in the inert-atmosphere reaction apparatus (Fig. 1.1). The distillation apparatus also contains some slightly modified round-bottom flasks for more efficient initial purging. These modifications will be discussed in greater detail in the following section. 

Interaction of a mixture of sulfur and the oxide under inert atmosphere above 160°C to form tetraphosphorus hexaoxide tetrasulfide is violent and dangerous on scales of working other than small [1], A safer procedure involving distillation of phosphorus(V) oxide and phosphorus(V) sulfide is described [2],... 

All operations were carried out under inert atmosphere (argon) using standard Schlenk techniques. Prior to use, solvents were freshly distilled from sodium tetraethylaluminate under argon. Deuterated solvents were treated with sodium or sodium tetraethylaluminate, distilled, and stored under argon. 

Pyrolysis has a long history in the upgrading of biomass. The dry distillation of hardwood was applied in the early 1990s to produce organic intermediates (methanol and acetic acid), charcoal and fuel gas [3]. Today s processes can be tuned to form char, oil and/or gas, all depending on the temperature and reaction time, from 300 °C and hours, to 400-500 °C and seconds-minutes, to >700 °C and a fraction of a second [3, 19, 23, 24], The process is typically carried out under inert atmosphere. We illustrate the basic chemistry of pyrolysis by focusing on the conversion of the carbohydrate components (Fig. 2.4). The reaction of the lignin will not be covered here but should obviously be considered in a real process. Interested readers could consult the literature, e.g., [25]. Pyrolysis is discussed in more details elsewhere in this book [26],... 

Diethyl ether was purchased from Mallinckrodt Baker, Inc., and purified immediately before use by distillation from sodium/benzophenone under inert atmosphere. 

Trioxolane (1) has only been prepared by the ozonolysis of ethylene. The rearrangement of the primary ozonide occurs above — 100°C to give 1,2,4-trioxolane as a colorless, explosive liquid <42LA(553)187>. 1,2,4-Trithiolane (2) is still best prepared by a classical reaction of Na2S2.5 with excess dichloromethane. Some 1,2,4,5-tetrathiolane is also produced, but (2) can be isolated as a pale-yellow distillable liquid. It is best kept stored under inert atmosphere below 0°C to avoid polymerization <67CPB988>. Parent compounds (3)-(6) are not known and the 1- and 4-5-oxides for 1,2,4-trithiolane have been mentioned previously (see Section 4.16.5.2.3). 

The freshly prepared chromous(II) acetate is suspended in 50 mL of distilled water previously deoxygenated and saturated with argon. To the resulting mixture is added, under inert atmosphere, an aqueous solution of potassium cyanide (82 g, 1.26 mol in 200 mL of water). A deep green precipitate of K4[Cr - (CN)6] is formed. 

The synthesis is performed in standard Schlenk equipment4 under a carbon monoxide atmosphere, if not otherwise stated. Transfer of liquid is carried out with hypodermic glass syringes equipped with Luer lock valves. All solvents are laboratory grade, distilled and stored under inert atmosphere. 

A 0.056-g sample of AIBN (2,2 -azobisisobutyronitrile) is placed into a one-piece 100-mL flask (such as Chemglass AF-0522-02)t equipped with a Teflon vacuum stopcock and a magnetic stir bar, and the flask is evacuated at — 196°C. A 1.69-g (15.9 mmol) sample of B-vinylborazine (prepared by the procedure described above) is vacuum distilled into the flask. Three freeze-pump-thaw cycles are performed in order to remove any traces of oxygen. The stopcock is closed and the reaction flask is removed to a shielded hood where it is heated in an oil bath at 70°C for about 3 h, at which point the material is sufficiently viscous that the stir bar stops. Then 5 mL of benzene is condensed into the flask and the solution is heated at 70°C for another 9 h. Slow addition of the benzene solution into 40 mL of pentane under inert atmosphere affords the precipitation of 0.73 g (43.2% yield) of poly(B-vinyl-borazine). The polymer is filtered under nitrogen and dried in vacuo for about 5 min. 

All reactions are carried out under inert atmospheres using standard Schlenk techniques. All solvents are dried and distilled before use. Ni(cod)2 is extremely air-sensitive, especially in solution, and thermally unstable. Ni(cod)2[35], (Et2N)PCl2 [36], 3,5-bis-(trifluoromethyl)bromobenzene, and (-)-phenyl-4,6-0-ben-zylidene-/8-D-glucopyranoside are commercially available. 

Other base, so that any acidic impurity is removed. It is always important that the distillation is carried out under inert atmosphere (or under reduced pressure) and the techniques are exactly as above. Some examples are given in Table 6.3. 

Obtained data show that, the mixtures of the different types of the natural and synthetic organic polymers can be successfully converted with a high yield to light distillate fraction by pyrolysis under inert atmosphere and catalytic hydtopyrolysis in the autoclave conditions. The optimum tenqreiature of biomass / plastic mixtures conveision which coiresponds to the maximum yield of liquids is 390 - 400 C. In the CO liquefaction processes the interaction between products of natural and synthetic polymers thermal deconqwsition takes place. 

The reaction vessel is a 2-L, three-necked flask equipped with a mechanical stirrer, a water-cooled reflux condenser, and a 1-L pressure-equalizing dropping funnel. Under inert atmosphere conditions, distilled chlorotri-methylsilane (120 mL, 102.7 g, 0.95 mol) in diethyl ether (500 mL) is added dropwise at room temperature from the dropping funnel to an efficiently stirred solution of rm-butylamine (100 mL, 69.6 g, 0.95 mol, freshly distilled from KOH) and triethylamine (135 mL, 98.2 g, 0.97 mol, freshly distilled from KOH) in diethyl ether (500 mL), The reaction mixture is stirred for 2 hr. Solid amine hydrochloride is filtered off (D3 frit) and washed twice with 100 mL of diethyl ether. Fractional distillation yields 100-120 g (70-80%), bp 119-122°/760 torr. 

Anhydrous tetrahydrofuran (THF), distil freshly on an alumina column and maintain under inert atmosphere until use. 

Prospective reduction of catalysts was carried out with 10%-solution of NaBH4 in distilled water. The amount of NaBH4 (97%, Fluka) was selected to apply the following relation nNaBH4/ (nRu+ ns ) = 10. Reduced catalysts were washed several times with small amounts of distilled water and finally with small amounts of ethanol. Washed catalysts were dried for 2 hours under inert atmosphere (N2 4.0, Linde Technoplyn, CR) at the temperature of 473 K. 

Cyclooctadiene (Aldrich Chemicals) was distilled from sodium and stored under argon. ra-Butyl bromide and 1.6 M ra-butyl lithium solution were purchased from Aldrich and used as received. Solvents used in the syntheses were dried with appropriate drying agents16 and freshly distilled under inert gas before use. All procedures are performed in an anhydrous, oxygen-free atmosphere using standard techniques for bench-top inert atmosphere reactions.17,18... 

Caprolactone (CL) (Acros, 99%) was dried over calcium hydride at r.t. for 48h and then distilled under reduced pressure. 2-(N,N-dimethylamino)ethyl methaciylate (DMAEMA) (Aldrich, 98%) was deprived of its inhibitor by filtration through a basic alumina column, and depending on samples (see text) dried over calcium hydride at r.t. for 24h and then distilled under reduced pressme. Butane-1,4-diol (Acros, > 99%) was dried over calcium hydride for 48h at r.t. and distilled at 70°C under reduced pressure. Triethylamine (NEts, Fluka, 99%) was dried over barium oxide for 48h at r.t. and distilled under reduced pressure. Copper bromide (CuBr, Fluka, 98%) was purified in acetic acid and recrystallized in ethanol under inert atmosphere until a white powder is obtained. Tin(ll) bis-2-ethyl hexanoate (Sn(Oct)2, Aldrich, 95%), methacrylic anhydride (Aldrich, 94%), N,N-dimethylamino-4-pyridine (DMAP, Acros 99%), 1,1,4,7,10,10-hexamethyltriethylene tetramine (HMTETA, Aldrich, 97%), ethyl-2-bromoisobutyrate (E BBr, Aldrich, 98%), N,N-dicyclohexylcarbodiimide (DCC, Acros, 99%), were used as received. Tetrahydrofuran (THF, Labscan, 99%) was dried over molecular sieves (4A) and distilled over polystyryl lithium (PS LC) complex under reduced pressure just before use. Toluene (Labscan, 99%) was dried by refluxing over CaH2. 

All reactions and sample preparations are carried out under inert atmosphere. Solvents are distilled under nitrogen atmosphere and dried in the following manner. Benzene is distilled from sodium. n-Pentane and n-hexane are distilled from sodium-lead alloy. Tetrahydrofuran is predried over calcium hydride and refluxed with sodium, whereafter benzophenone is added. After the solution turns blue, the tetrahydrofuran is distilled. Dichloromethane is distilled from phosphorous pentoxide. Commercial octacarbonyldicobalt is recrystallized from hexane prior to use. Commercial triphenylphosphinef is used without further purification. 

All reactions and sample preparations are carried out under inert atmosphere. Solvents are distilled under nitrogen atmosphere and dried as de-... 

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