Purification, general phenols

In general phenolic lipids have been separated from natural sources for compositional studies and structural determination by solvent extraction and chromatographic techniques. The individual component phenols of the major phenolic lipid (CNSL) from Anacardium occidentale have assumed some significance in certain chemical applications and detailed purification processes... 

In the case of low temperature tar, the aqueous Hquor that accompanies the cmde tar contains between 1 and 1.5% by weight of soluble tar acids, eg, phenol, cresols, and dihydroxybenzenes. Both for the sake of economics and effluent purification, it is necessary to recover these, usually by the Lurgi Phenosolvan process based on the selective extraction of the tar acids with butyl or isobutyl acetate. The recovered phenols are separated by fractional distillation into monohydroxybenzenes, mainly phenol and cresols, and dihydroxybenzenes, mainly (9-dihydroxybenzene (catechol), methyl (9-dihydtoxybenzene, (methyl catechol), and y -dihydroxybenzene (resorcinol). The monohydric phenol fraction is added to the cmde tar acids extracted from the tar for further refining, whereas the dihydric phenol fraction is incorporated in wood-preservation creosote or sold to adhesive manufacturers. Naphthalene Oils. Naphthalene is the principal component of coke-oven tats and the only component that can be concentrated to a reasonably high content on primary distillation. Naphthalene oils from coke-oven tars distilled in a modem pipe stiU generally contain 60—65% of naphthalene. They are further upgraded by a number of methods. 

The following are some of the typical industrial applications for liquid-phase carbon adsorption. Generally liquid-phase carbon adsorbents are used to decolorize or purify liquids, solutions, and liquefiable materials such as waxes. Specific industrial applications include the decolorization of sugar syrups the removal of sulfurous, phenolic, and hydrocarbon contaminants from wastewater the purification of various aqueous solutions of acids, alkalies, amines, glycols, salts, gelatin, vinegar, fruit juices, pectin, glycerol, and alcoholic spirits dechlorination the removal of... 

General. Toluene, chlorobenzene, and o-dichlorobenzene were distilled from calcium hydride prior to use. 4-Dimethylaminopyridine (Aldrich Chemical Co) was recrystalled (EtOAc), and the other 4-dialkylaminopyridines were distilled prior to use. PEG S, PEGM s, PVP s, and crown ethers were obtained from Aldrich Chemical Co., and were used without purification. BuJ r and BU. PBr were recrystallized (toluene). A Varian 3700 VrC interfaced with a Spectraphysics SP-4000 data system was used for VPC analyses. A Dupont Instruments Model 850 HPLC (also interfaced with the SP-4000) was used for LC analyses. All products of nucleophilic aromatic substitution were identified by comparison to authentic material prepared from reaction in DMF or DMAc. Alkali phenolates or thiol ates were pre-formed via reaction of aqueous NaOH or KOH and the requisite phenol or thiophenol in water under nitrogen, followed by azeotropic removal of water with toluene. The salts were transferred to jars under nitrogen, and were dried at 120 under vacuum for 20 hr, and were stored and handled in a nitrogen dry box. 

Method. The method of Singleton and Rossi (9) was used. Commercial samples of the compounds to be tested, generally without further purification, were accurately weighed (about 100-200 mg unless the supply was very limited), dissolved in ethanol, and diluted with water so that the final solution was 10 vol % ethanol and had a known concentration of phenol which yielded an absorbance of about 0.3 in the analysis. For incompletely soluble substances the suspension was kept dispersed, fine, and homogeneous. The analysis was essentially as published (9) ... 

Physical Properties. The molecular weight of dalbaheptides ranges from about 1150 to 2200. Pure dalbaheptides are obtained as colorless or whitish amorphous powders that usually retain water and solvents. Dalbaheptides are generally water-soluble. Teicoplanin can be obtained as an internal sail or as a partial monoalkaline (sodium) salt depending on tile pH of the aqueous solution in the final purification step. Other dalbaheptides arc obtained as acidic salts, such as hydrochlorides (vancomycin, actaplanin) or sulfates (ristocetin A, avoparcin, eiemomycin). The presence of amino, carboxyl, benzylic, and phenolic hydroxyl functions, sugars, and aliphatic chains influences both water solubility and total charge. 

Once cell wall breakage or enzymatic dissolution has occurred, a variety of procedures can be used for isolation and purification of the DNA. These generally rely on an initial deproteinization using phenol or a mixture of perchlorate, sarcosine, and chloroform-isoamyl alcohol.6 9 The crude DNA is further purified by enzyme treatments, alcohol precipitation and spooling, hydroxylapatite chromatography, cesium chloride gradient centrifugation, or any combination of these methods. 

None of these methods has achieved popularity, but a unique variant of the carbonates provides a general method that is simple and efficient. Mixed carbonates 58 formed from isopropenyl chloroformate and substituted phenols or hydroxylamines react at room temperature with N -protected acids 23 in the presence of A-methylmorpholinet or a catalytic amount of 4-(dimethylammo)pyridinet giving active esters 24 in exceptionally high yield (see Table 13) with conconnitant liberation of acetone (Scheme 14). Compounds prepared using the non-aromatic base require purification on a silica gel column. 

The most accurate method of analysis for serine, threonine and tyrosine in proteins is to hydrolyze the proteins for several different times (e.g. 24, 48 and 72 hr) and extrapolate the values to 0 time. In general, the more times that are utilized, the more accurate will be the extrapolation. Extrapolation of the NHj content of these hydrolysates to 0 time will also give an estimate of the number of amides present in the protein, if care has been used to exclude NHj during purification of the protein. The inclusion of phenol in the hydrolysates has generally decreased the rates of destruction, particularly for tyrosine. If serine phosphate ( 2.12.4) or similar derivatives are present, the extrapolated curve will be more complex due to different rates of destruction. 

A general method for the evaluation of phenolic compounds in fermented beverages, fruit juices and plant extracts was developed using gradient HPLC and coulometric detection. In a 10 p,L injection it was possible to identify and determine 36 different flavonoids and simple and complex phenols, without sample extraction, purification or concentration, in several kinds of beers, red and white wines, lemon juice and soya, forsythia and tobacco extracts. This may also be useful for the characterization of beverages and extracts . 

Table 10.1. A solid-phase extraction (SPE) using a Ci8 cartridge can be used for purification of extract from phenolic compounds. This procedure may lead to losses of proteins, but in general does not affect the protein composition (Waters et al., 1992).

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