IR phenol

Key words xylose-rich pectic polysaccharide, pectin, wheat straw, extraction, sugars, lignin, FT-IR, phenolic acids and aldehydes. 

IR phenol, benzyl alcohol, di- and triphenyl carbinols in various solvents, 3m-... 

Chem. 28, 22-30 (1956). IR phenolic H bonds in coals, carbonaceous materials. 

This is an analysis frequently conducted on oil lubricants. Generally, the additive is known and its concentration can be followed by direct comparison of the oil with additive and the base stock. For example, concentrations of a few ppm of dithiophosphates or phenols are obtained with an interferometer. However, additive oils today contain a large number of products their identification or their analysis by IR spectrometry most often requires preliminary separation, either by dialysis or by liquid phase chromatography. 

Infrared The IR spectra of phenols combine features of those of alcohols and aro matic compounds Hydroxyl absorbances resulting from O—H stretching are found m the 3600 cm region and the peak due to C—O stretching appears around 1200-1250 cm These features can be seen m the IR spectrum of p cresol shown m Figure 24 3... 

Section 24 15 The IR and H NMR spectra of phenols are similar to those for alcohols except that the OH proton is somewhat less shielded m a phenol than m... 

Sulfonated styrene—divinylbensene cross-linked polymers have been appHed in many of the previously mentioned reactions and also in the acylation of thiophene with acetic anhydride and acetyl chloride (209). Resins of this type (Dowex 50, Amherljte IR-112, and Permutit Q) are particularly effective catalysts in the alkylation of phenols with olefins (such as propylene, isobutylene, diisobutylene), alkyl haUdes, and alcohols (210) (see Ion exchange). Superacids. 

The esterification of -butyl alcohol and oleic acid with a phenol—formaldehydesulfonic acid resin (similar to amberHte IR-100) is essentially second order after an initial slow period (52). The velocity constant is directiy proportional to the surface area of the catalyst per unit weight of reactants. 

An azo coupling reaction of monatomic phenols with diazotized 4-nitroaniline has been investigated. By HPLC, NMR, elemental analysis, UV and IR spectroscopy it has been shown that the azo derivatives of o-guaiacol, o- and m-cresols interact with an excess of diazonium in pH interval of 4,5-9,5 and form corresponding 4,4-di(4-nitrophenylazo)-2,5-cyclohexadien-1 -ones. 

In a series of articles, Caraculacu and coworkers described a method based on substitution of labile chlorines with phenol. IR [34] and UV [47] were used for determination of incorporated phenol. The published data indicate a detection limit of 2 and 0.5 labile chlorines per 1,000 monomer units. 

Similarly, the Kass determined by the H NMR chemical shift of CHC13 in the presence of sulphoxides can be correlated well with the association constants obtained both on the basis of the IR stretching shift (AvOH) of phenol in the presence of sulphoxide and also with the 19F NMR chemical shifts of p-fluorophenol (<5,F). 

A similar quantitative treatment of sulphoxides as hydrogen bonding acceptors has been obtained by comparing the IR frequency shift AvOH of the C—I bond in an acetylenic iodide such as IC=CI (Avc j) due to formation of a C—T complex with phenol in various bases. This investigation suggests that sulphoxides belong to the same family as carbonyls, phosphine oxides, arsine oxides and their derivatives90. 

The most widely used molecular weight characterization method has been GPC, which separates compounds based on hydrodynamic volume. State-of-the-art GPC instruments are equipped with a concentration detector (e.g., differential refractometer, UV, and/or IR) in combination with viscosity or light scattering. A viscosity detector provides in-line solution viscosity data at each elution volume, which in combination with a concentration measurement can be converted to specific viscosity. Since the polymer concentration at each elution volume is quite dilute, the specific viscosity is considered a reasonable approximation for the dilute solution s intrinsic viscosity. The plot of log[r]]M versus elution volume (where [) ] is the intrinsic viscosity) provides a universal calibration curve from which absolute molecular weights of a variety of polymers can be obtained. Unfortunately, many reported analyses for phenolic oligomers and resins are simply based on polystyrene standards and only provide relative molecular weights instead of absolute numbers. 

Morterra and Low109,110 proposed that thermal crosslinking may occur between 300°C and 500°C where phenolic hydroxyl groups react with methylene linkages to eliminate water (Fig. 7.43). Evidence for this mechanism is provided by IR spectra which show decreased OH stretches and bending absorptions as well as increased complexity of the aliphatic CH stretch patterns in this temperature range. 

Complexes. The structure of an n a charge-transfer complex between quinoxaline and two iodine atoms has been obtained by X-ray analysis and its thermal stability compared with those of related complexes. The hydrogen bond complex between quinoxaline and phenol has been studied by infrared spectroscopy and compared with many similar complexes. Adducts of quinoxaline with uranium salts and with a variety of copper(II) alkano-ates have been prepared, characterized, and studied with respect to IR spectra or magnetic properties, respectively. 

The phenol-contaminated sample was unique in yielding bromine containing none of the starting contaminant. Analysis of the bromine by FT-IR and INMR showed a complex mixture of brominated phenols and small amounts of other brominated hydrocarbons. The absence of phenol in the bromine product is not surprising, since phenol reacts with bromine at room temperature to make predominantly tribromophenol. 

---