SOLVENT REMOVAL Subject

Concretes and absolutes, both obtained by total extraction of the plant material and not subject to any form of distillation other than solvent removal, are complex mixtures containing many chemical types over wide molecular weight ranges. In some cases, gas chromatographic analysis shows httle volatile material. Yet these products have powerful odors and contribute in important ways to the perfumes in which they are used. 

Vacuum-dried KF (8.7g. 150mmol) and an unsaturated aldehyde (50mmol) were placed in a 200-mL stainless steel autoclave, the autoclave was cooled to —196 C, evacuated and SF4 (16.2 g, 150 mmol) condensed in it. The filled autoclave was allowed to warm slowly to rt then agitated for 48-72 h. The volatile products were removed at — 35 C under reduced pressure and C HCI, was added to the residue. A suspension of KF was filtered off, the filtrate was washed with 10% aq NaFlC03, dried (MgS()4) and the solvent removed under vacuum. The crude product was subjected to distillation or GC purification. 

Monomer XIV was introduced into the polycondensation reaction. The reaction was performed in CI C solution in the presence of 10 mol. Z of tritylium perchlorate at room temperature, the removal of traces of moisture being essential. The latter was most conveniently achieved by using a high-vacuum technique although, for larger runs, it is also possible to use standard equipment. The reaction practically came to an end after 50-60 h it was then finally terminated by the addition of CF CO H and, after neutralization and solvent removal, the polymer obtained, without purification, was subjected to de-acetylation. The free polysaccharide XV was isolated by precipitation. 

Purification by preparative HPLC is accomplished as follows. The crude product is taken up in 60 mL of 4 1 hexanes-ethyl acetate. The solution is subjected to preparative HPLC (Note 24) using the same solvent system. Chromatography 1s monitored by TLC (Note 26) and the appropriate fractions are combined. Solvent removal with a rotary evaporator at 35 C (12 mm) gives a colorless oil. This material is subjected to bulb-to-bulb distillation at 75-90°C (8 am). 

The 3-phenyl salt is treated with 10% aqueous NaOH and the resultant oil is taken up in toluene, washed with water, dried over sodium sulfate, the solvent removed by vacuum rotary evaporation (foaming ), and the residue subjected to rapid pot-to-pot distillation under nitrogen to give 75-85% recovery of 1,3-dimethyl-2-methylene-3-phenylindoline, bp 130-140°C.l-2 mm (lit.219 130°C/0.08 mm) (Note 7). 

Deracemization of mandelic add with the combined action of two enzymes has been reported. rac-MandeUc acid is acylated by a Pseudomonas sp. lipase in diisopropyl ether. After solvent removal the mfacture of mandeUc acid enriched in the R-form and the 0-acetyl derivative of the S-configuration are subjected to the mandelate racemase-catalyzed racemization in aqueous buffer. In these conditions only the non-acetylated hydroxy acid is racemized. In order to obtain (S)-0-acetylmandelic acid in an 80% isolated yield and a >98% e.e. the process must be repeated four times [9]. 

Method B A solution of 0.2 mmol of the steroidal enone (34, 38) and 0.9 mmol of S.S-diphenylsuirilimine (35) in 3.5 mL of toluene is kept in a high pressure bottle at 6 kbar for 6-48 h (for only one example, a temperature of 80 °C was reported). The solvent is removed in vacuo and the residue is acetylated in 1.5 mL of dry acetic anhydride and 3 mL of pyridine at 20 °C for 24 h. The reaction mixture is diluted wilh 20 ml, of water and extracted with 50 mL of CH2C1,. The extract is dried over Na2SO and the solvent removed in vacuo. The residual solid is subjected to preparative TLC (silica gel, Et20/hexane or EtOAc/hcxanc) yield 5-81 %. 

Lead diphenyl di-o-tolyl. —To a solution of 5 6 grams of o-bromo-toluene and 0 8 gram of magnesium in dry ether, 5 grams of lead diphenyl iodide are slowly added. After the reaction has subsided, the mixture is heated for half an hour on the water-bath, cooled, and 25 c.c, of toluene added, the whole then being decomposed with dilute hydrochloric acid. The toluene-ether layer is separated, the solvents removed, and the residue subjected to steam distillation to remove the last traces of toluene. An oil is obtained which soon solidifies to a yellow mass this when crystallised from alcohol appears as white needles, sintering at 129° C., and melting at 134° to 135° C. It is readily soluble in cold chloroform and in hydrocarbons. 

The plant material is extracted with a non-polar organic solvent. Useful solvents include lower alkanes, such as, for example, hexane, heptane or iso-octane. The extract containing THC, after solvent removal, is subjected to fractional distillation under reduced pressure and a first distillate is collected. In one embodiment of the present invention, the first distillate is again subjected to fractional distillation at reduced pressure and a second distillate is collected. The second distillate has a THC content of greater than 90% by wt. 

For obtaining rearranged conjugated trienes 52a-e and 53a-e on a preparative scale, the reaction mixture from the synthesis in 1 -(2, 6, 6 -trimelhyl-1 -cyclohexen-l -yl)-3-(phenylsulfinyl)-1,2-alkadienes 51a-c (200-300 mg) (both diastereomers of the vinylallene sulfoxides) after Et20 workup is allowed to stand in Et20 (15-20 mL) at r.t. for > lOh. The residue after removal of solvent is subjected to 1IPLC purification (Whatman Partisil M 9 10/50 column, 10-20% ElOAc/Skellysolve B) to afford the two conjugated trienes. From 51a yield 63% ratio (53a/52a) 81 19 from 51 b yield 91 % ratio (53b/52b) 92 8 from 51c yield 75% ratio (53c/52c) 92 8 from 51 d yield 80% ratio (53d/52d) 94 6 from 51e yield 58% ratio (53d/52d) >98 2,... 

Preparation of Monomer 3. A benzene (20 mL) solution containing 2 (0.50 g, 1.8 mmol) and tributylphosphine (0.50 g, 2.5 mmol) was irradiated in water jacketed quartz reaction vessel with a 175 watt medium pressure mercury lamp for 6 h. The solvent was removed under reduced pressure and crude product subjected to column chromatography on alumina. Gradient elution with pet ether/benzene (final 2/1, v/v) produced a yellow-orange band which was collected and the solvents removed to afford pure 3 (0.65 g, 81%). H NMR (CDCI3) 6 4.90 (d, J = 3 Hz, 4 H), 1.66-1.60 (m, 6 H),... 

Here we address a subject of solvent removal, or drying, which is a part of sohdifica-tion processes. 

The simplest technique is pre-saturation in which the solvent is subjected to CW irradiation for a short time at a level sufficient to saturate the solvent without affecting other solute peaks. The saturating field is removed immediately before the observation pulse so that the solvent peak has no opportunity to relax. Several solvent peaks can be saturated if rapid frequency switching can be performed during the saturation period. If proton exchange between solvent and solute occurs, for example exchange of OH and NH with H2O, the solvent saturation can be transferred to the solute. However, this is rarely a problem in synthetic polymers, and because of its ease of application the pre-saturation method is the preferred method. 

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