Optical rotation removal

Thoms olituined a vielJ of 7 per cent, of oil from the seeds, which had a specific gravdlv of 08136 and optical rotation - 5S-.5. The oil, from tvhich traces of free acids and pheooH were first removed, was fractionated in yaciio. 

The calcium carbonate precipitate was removed by filtration, and the filtered solution was found to contain 1,436 g of fructose as determined by optical rotation. A small amount of calcium bicarbonate was present as an impurity in solution and was removed by the addition of oxalic acid solution until a test for both calcium and oxalic acid was negative. The insoluble calcium oxalate precipitate was removed by filtration. 

Stylotelline (23) is a constituent of a Stylotella sp. collected offshore in New Caledonia. 13C NMR spectra involving 2D NMR techniques provided the bulk of information leading to its structure. The absolute configuration was demonstrated after the tertiary isocyano group was removed to yield the known conjugated diene, ( + )-d-selinene (24). Optical rotation and spectral data of the transformation product were identical in all respects to those of the corresponding product obtained from eudesmols [42], Although neither the isothiocyanato nor the formamido compounds were isolated, the latter was prepared, which allowed an nOe observation between the axial C-3 and the amide protons. 

These end groups were removed by cleaving the C-N bond with a strong base (25% NaOH) so that the CD rings may slip off the polymer chains, and the number of CDs per polyrotaxane was estimated by H NMR, optical rotation, and UV absorption to be 12. This figure indicates that nearly the entire length of the 28 mer PEG chain was covered with CDs, because, as repeatedly noted above, the stoichiometric ratio for the complexation between PEG and a-CD is 2. 

Removal of the auxiliary group from 12 (see p413) to give 13 followed by several steps yields (-)-(65)-tetrahydro-6-undecyl-2//-pyran-2-one (14), a pheromone of the wasp Vespa orientalis. Comparison of the optical rotation of the synthetic product with that of the natural product served to confirm the stereochemistry of the initial reduction to 12. 

One part of commercial defatted soy flakes was extracted with ten parts of dilute NaOH (pH 9-10). After removal of spent flakes, the total extract was adjusted to pH 4.5 with dilute HCl to precipitate the curd. The curd was washed three times with H2O, resuspended at pH 7.0, and freeze dried. Intrinsic viscosity, optical rotation, and differential scanning calorimetry (DSC) measurements show the soluble fraction of curd to be native. 

Paul Pfeiffer discovered a very interesting stereochemical phenomenon, which now bears his name — the Pfeiffer effect this has received a good deal of attention.30 When an optically active substance which is stable in solution is added to a solution of a labile chiral substance, the optical rotation of the solution changes, reaching a new level in some hours. Several theories have been advanced to explain the phenomenon, the most satisfactory based on the supposition that the optically active ion or molecule forms an association with one isomer of the racemic pair of the labile substance and thus shifts the dextro—levo equilibrium. In general it is not possible to use this as a means of resolution, for when the added optically active substance is removed from the labile material, the latter immediately racemizes. 

The 5,5-CHIRAPHOS contains traces of a nickel complex (a concentrated solution appears yellow-brown) which is removed by a single recrystallization, which also increases the magnitude of the optical rotation by 3-4°. 

Optical (Specific) Rotation Transfer an accurately weighed amount of sample, equivalent to about 100 mg of total tocoph-erols, into a separator, and dissolve it in 50 mL of ether. Add 20 mL of a 10% solution of potassium ferricyanide in a 1 125 sodium hydroxide solution, and shake for 3 min. Wash the ether solution with four 50-mL portions of water, discard the washings, and dry over anhydrous sodium sulfate. Evaporate the dried ether solution on a water bath under reduced pressure or in an atmosphere of nitrogen until about 7 or 8 mL remains, and then complete the evaporation, removing the last traces of ether without the application of heat. Immediately dissolve the residue in 5.0 mL of isooctane, and determine the optical rotation. Calculate the optical rotation [see Optical (Specific) Rotation, Appendix HB], using as c the concentration expressed as the number of grams of total tocopherols, as determined in the Assay (above), in 100 mL of the solution. 

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