Phenolic acid description

Acide carboMque (Fr). Phenol Acid Egg or Blowcase is a type of "displacement pump"(qv) used for transferring acids and other corrosive liquids from one apparatus to another by means of compressed air. Its description is given in Refs 1 2. 

The lipophilic phase comprises usually about 70-75 % of the total amount of the cream base. The lipophilic phase may consist of fatty oils (usually arachis oil), waxes such as decyl oleate, wool fat and white wax or hydrocarbons such as liquid paraffins or white soft paraffin (see Sect. 23.3.5 for descriptions). They determine consistency and spreadability. A w/o surfactant is added (see Sect. 12.5.4). The emulsifying properties of w/o surfactants are weaker than those of o/w surfactants. Therefore they are often used in a higher quantity. The physical stability of w/o creams is limited. Eor instance the addition of phenols, acids and alcoholic fluids may lead to phase separation. Most hydrophobic creams only include less than 5 % alcohols. 

Many of the properties of phenols reflect the polarization implied by the resonance description The hydroxyl oxygen is less basic and the hydroxyl proton more acidic in phenols than m alcohols Electrophiles attack the aromatic ring of phenols much faster than they attack benzene indicating that the ring especially at the positions ortho and para to the hydroxyl group is relatively electron rich... 

Humic and fulvic acids contain various types of phenolic and carboxylic functional (hydrophilic) groups as well as aromatic and aliphatic moieties which import hydro-phobic properties to these substances. Fig. 4.12 gives a schematic idea on the composition of these substances. We refer to the book of Thurman (1985) and Aiken et al. (1985) for a description of the various properties of humic and fulvic acids in soils and waters and the book by Buffle (1988) for the coordinating properties of humus and humic acids. 

The above description of the process is tentative because it is based on limited data. If it is correct, the predominate structures in the PHBA-modified products have amorphous PA/AA/NPG center sections end-capped with single units or short blocks of oligomeric PHBA. Random distribution of the PHBA cannot be ruled out, but the hetero-geneiety of the products suggests that a substantial fraction of PHBA is incorporated into short blocks. The FT-IR and GPC data are consistent with the proposal that short, phenolic-tipped oligomers are the predominant structure present. The possibility that the materials are physical mixtures of oligo-PHBA and amorphous diols can be virtually ruled out on the basis of the extreme insolubility of oligo-PHBA (IJ) and of the model PHBA-benzoic acid adduct synthesized in this study. These materials separate readily from solutions and dispersions of PHBA copolymers. 

According to the Lebedev s description [5], phenol is sulphonated with 98% sulphuric acid taken in the proportion of 400-500 parts of acid for 100 parts of phenol. The sulphonation temperature is maintained within 70-80°C or 100-110°C. The reaction time is 4 hr. A temperature of 125-130°C may also be maintained, in which case the reaction time may be reduced to 2 hr. Cast iron sulpho-nators are used, 2 m in diameter and 1.8 m high. The required temperature may be maintained in the sulphonator by heating with a steel heating coil or with a heating jacket. 

Brett flavor in wine The question still remains what is "Brett" flavor Results from our initial work indicates that "Brett" aroma in wine is a complex mixture of odor-active compounds, including acids, alcohols, aldehydes, ketones, esters, and phenolics. Analysis by gas chromatography-olfactometry revealed two predominate odor-active compounds responsible for the Brett flavor in the wines studied isovaleric acid and a second unknown compound other identified odor-active compounds included 2-phenyl ethanol, isoamyl alcohol, cis-2-nonenal, trans-2-nonenal, B-damascenone, ethyl decanoate, guaiacol, 4-ethyl guaiacol, 4-ethyl phenol. Our findings are a snapshot into the much larger picture know as Brett flavor. Ultimately this preliminary investigation requires the descriptive analyses of many more wines to know what odor active compounds describe the flavor know as "Brett". 

An exhaustive description of the constituents of olive oil was previously reported [3,11]. In virgin oil non-glyceride components represent 0.5-1.5% the content of phenolic constituents ranges between 50-500 mg/kg (expressed as cafifeic acid). 

The most common reagent for nitration of benzene, simple alkylbenzenes and other less reactive compounds is a mixture of concentrated nitric and sulfuric acids. However, nitration of activated substrates, such as aniline, phenol or pyrrole, occurs with nitric acid alone or in water, acetic acid or acetic anhydride. Concentrated sulfuric acid can oxidize these substrates. A description of the use of other nitrating reagents is outside of the scope of this review, but can be found in Smith and March s Advanced Organic Chemistry29 or Larock s Comprehensive Organic Transformations30. 

It is usually extremely difficult to calculate AGs of ground-state acids from first principles with uncertainty of less than several kcalmol, which translates into uncertainty of several pXa units. In the excited state an additional difficulty involves the accurate electronic description of the excited state, which makes the task of calculating the pX of a photoacid even tougher. A recent attempt to calculate the excited-state pKl of phenol resulted in a value larger by more than 4 pXa units than the experimental one (a value of pX (calc) = —0.2, compared to the experimental value of about 4). A very recent calculation of the ground-state dissociation constant of phenol resulted also in overestimation of the dissociation constant, giving 7.2 compared to the experimental value of about 10.0. ... 

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