2-Hydroxy-benzoic acid effects

Organic acids may inhibit growth when present in the undissociated form because of their abiHty to change the pH inside the ceU. The most efficient are benzoic acid and sorbic acid, but formic, acetic, and propionic acid also have this effect. The parabens, ie, -hydroxy benzoic acid esters, are also used because of their antimicrobial effect over a broad pH range. 

Each component of Jessner s solution has specific effects (Fig. 3.1). Salicylic acid (ortho hydroxy benzoic acid) is a beta hydroxy acid agent... 

Berge and Deye studied the effect of column surface area on the retention of polar solutes [18]. They found that there was a linear relationship between retention and the surface area. 4-Hydroxy benzoic acid was used as a model acidic compound, and sulfamethazine, sulfanilamide, sulfi-somidine, and sulfapyridine were used as the model basic compounds. The separations were carried out on a packed Nucleosil Diol column with a methanol-modified carbon dioxide as the mobile phase. The UV detector was used for the analysis. It was observed that 0.1% acetic acid for the acidic solutes and 0.1% isopropylamine for basic solutes was required in the methanol to achieve the separations. The efficiency was found to be similar for 100-, 300-, and 500-A packing materials. 

The experimentally determined S-L-V equilibrium data for salicylic acid (2-hydroxy-benzoic acid)-l-propanol-C02 were correlated by using the Stryjek-Vera modification of the Peng Robinson EOS in conjunction with Eq. (35) for the solid state fugacity of the solute (58,62), as described earlier. This procedure also yielded good agreement of the liquid phase compositions of salicylic acid in the temperature and pressure ranges of 273 to 367 K and 1.0 to 12.5 MPa. The P-Ttraces of S-L and L-V equilibria were calculated for a fixed solute concentration on C02-free basis, and subsequently the P-T trace for the S-L-V equilibrium was found from the point of intersection of these two lines. The liquid phase compositions of the solute as a function of pressure at a constant temperature at the condition of S-L-V equilibrium were calculated to assess the effect of pressure or addition of antisolvent on solute crystallization. It was reported that two isobaric points of the CO2 mole fraction could be observed on the curve of the S-L equilibrium temperature vs the CO2 mole fraction at constant temperature as it passes through a mini-... 

For a simple bond fission it is doubtful if comparison of the observed isotope effect with the theoretical maximum will give a trustworthy estimate of the position of the transition state small effects are therefore ambiguous as diagnostic tools and must be coupled with other experiments. Another example involving decarboxylation is the bromine-catalysed decomposition of 3,5-dibromo-4-hydroxy-benzoic acid (Eqn. 50) [30b]. 

The active substance most often used in pyrotechnic whistles is gallic acid (3, 4, 5 trihydroxybenzoic acid). The potassium salts of benzoic acid of 2, 4, dinitrophenol and of picric acid (2, 4, 6 trinitro-phenol) and the sodium salt of salicylic acid (o-hydroxy benzoic acid) are also effective. They are combined with potassium chlorate, perchlorate, or nitrate (Formulas 156—160). 

ABSTRACT. The geometries of inclusion complexes of a-cyclodextrin(a-CD) with guests, benzoic acid, p-hydroxy benzoic acid, and p-nitrophenol in aqueous solution have been determined by comparing the complexation induced C-13 shifts of guest molecules with quantum chemical predictions. In the calculations, the non-polar environmental effect produced by the a-CD cavity on the C-13 shifts of included guest molecule has been formulated by the so-called solvent effect theory. The geometries of the complexes predicted theoretically were consistent with those... 

Hydroxy-benzoic acid 3-nitrooxymethyl-phen-yl ester (B-NOD) in vitro increased cGMP production in platelets in a dose-dependent manner (Bing et al. 2000). The effect of sodium nitroprusside donor was greater than that of B-NOD. Inhibition of platelet aggregation was approximately 25% as compared to the control sodium nitroprusside. 

As the effectiveness against bacteria is weak, weaker than the activity against moulds, 2-phenyl ethanol is in general applied in combination with other microbicides, e.g. with p-hydroxy-benzoic acid esters (Section 6.1.10), quaternary ammonium compounds (Section 16-1), p-chloro-m-cresol (Section 5.3.1) for the preservation of cosmetic and pharmaceutical products. It is especially effective in acidic media. 

Phenoxy ethanol is mentioned in the EC positive list of preservatives for cosmetic products (maximum authorized concentration 1%) In general it is applied in combination with other preservatives, such as />-hydroxy benzoic acid esters (Section 6.1.10), l,2-dibromo-2,4-dicyanobutane (Section 15.11) and others. More effective is the 2-phenoxy ethanol hemiformal (Section 3.1.3). 

Carbon-carbon bond formation as a consequence of substitution on the phenolic aromatic ring can be effected in a variety of other ways too. For example, if the sodium salt of phenol is heated at high pressure with carbon dioxide to 125-250°C, or//io-substitution occurs (Equation 8.29) at 250-300 C, the para-hydroxy benzoic acid results (Equation 8.30). The carboxylation process is known as the Kolbe-Schmitt reaction. ... 

In comparison with the lower p-hydroxybenzoic acid alkyl esters the butyl ester is far and away the most effective one and presents an equalized spectrum of effectiveness (see Table 81). However, the application of the butyl ester as a preservative in cosmetics, toiletries and pharmaceuticals is, in spite of its high activity, limited because of its low water solubility and high log POW. But combinations of p-hydroxy-benzoic acid butyl ester with the lower alkyl esters perform excellently. 

In a previous report [7], we have successfully applied the quantum chemical method to the determination of the geometry of a-CD inclusion-complexes with substituted benzenes such as p-nitrophenol, p-hydroxy-benzoic acid, and benzoic acid. This method was based on the so-called solvent-effect theory and it was assumed that the a-CD cavity has the environmental effect of lower dielectric constant( l) on a included part of the guest and the other part of guest is exposed to the aqueous phase of higher dielectric constant( 2) shown in Fig,IB. 

Calundann GW (1979) Polyester of 6-hydroxy-2-naphthoic acid and para-hydroxy benzoic acid capable of readily undergoing melt processing. US Patent 4,161,470, 17 July 1979 Chang L, Friedrich K (2010) Enhancement effect of nanoparticles on the sliding wear of short fiber-reinforced polymer composites a critical discussion of wear mechanisms. Tribol Int 43 2355-2364... 

When substituents can also be involved in the resonance effects, changes in acidity become more marked. Consider hydroxy- and methoxy-benzoic acid derivatives. The pATa values are found to be 3.0, 4.1, and 4.6 for the ortho, meta, and para hydroxy derivatives respectively, and 4.1, 4.1, and 4.5 respectively for the corresponding methoxy derivatives. 

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