Hydroxybenzoic acid esters

The derivative of p-hydroxybenzoic acid having a following stracture  

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Vitamin Bi (thiamine), B2 (riboflavin). Be (pyridoxine), B12 (cyanocobalamine), C (ascorbic acid), E (tocopherols), folic acid, pantothenic acid, K, K2, K3 (menadione), PP factor (nicotinamide), biotin Benzimidazole drugs, bromoisovalerylurea, cardiazol, chlorhexidine, dicoumarol, dulcin, isoniazid, 2-nitrofuran derivatives, parabens (4-hydroxybenzoic acid esters), phenacetin, phenylbutazone (and its metabolite oxyphenbutazone), propipocaine, quercetin, rutin, thiomersal (sodium ethylmercurithiosalicylate)... 

Valkova, N., Lepine, F., Valeanu, L., Dupont, M., Labrie, L., Bisaillon, J. G., Beaudet, R., Shareck, F. and Villemur, R., 2001. Hydrolysis of 4-hydroxybenzoic acid esters (Parabens) and their aerobic transformation into phenol by the resistant Enterobacter cloacae strain. Applied and Environmental Microbiology 67, 2404-2409. 

The parabens are a class of 4-hydroxybenzoic acid esters (primarily methyl, ethyl, propyl, and butyl esters) that are used as biological preservatives in liquid and semisolid dosage forms.Another preservative often used is benzyl alcohol. Parabens and benzyl alcohol are compendial items. These materials are very stable... 

Table 4. Physical and Antimicrobial Properties of />Hydroxybenzoic Acid Esters ...

Fig. 6.2 Separation of benzoic acid, sorbic acid and p-hydroxybenzoic acid esters by...

In 1983, Nixon and Scheimann reported that 2-acyl(or formyl, methoxycarbonyl)-phenol can add to 4-(methoxycarbonyl)-2,3-butenoate to yield 4-(methoxycarbonyl)-3-(phenoxy)-3-buteneate 522. o-Hydroxyphenyl ketone, o-hydroxybenzaldehyde or o-hydroxybenzoic acid esters reacted with 4-methoxycarbonyl-2,3-butenoate in a... 

Several wholly aromatic polyesters are available. As expected, they are more difficult to process, stiffer, and less soluble, but are employed because of their good high-thermal performance. Ekonol is the homopolymer formed from p-hydroxybenzoic acid ester (structure 4.51). Ekonol has a Tg in excess of 500°C. It is highly crystalline and offers good strength ... 

A theoretical approach is applied to elucidate the molecular conformations, associated flexibility, and dynamics of polylp-hydroxybenzoic acid) esters, pHB. Properties such as the radius of gyration and persistence length which are characteristic for the stiffness of a macromolecule are calculated on the basis of two different theoretical methods (a) Molecular dynamics and (b) the RIS model augmented by the more recent scheme for the matrix computations. The analysis of the results obtained by the latter method reflects a strong dependence on the choice of the structural parameters of the system. 

Uekama, K., Ikeda, Y., Hirayama, F., Otagiri, M., and Shibata, M. 1980. Inclusion complexation of p-hydroxybenzoic acid esters with andfS-cyclodextrins dissolution behaviors and antimicrobial activities.Yakugaku Zasshi, 100 994-1003. 

Figure 6.1 UV chromatograms of the test mixture of four / -hydroxybenzoic acid esters (1, methyl 2, ethyl 3, propyl 4, butyl) after the column and after the NMR flow cell at flow rates of (a) 1.0 and (b) 0.1 ml/min conditions column, LiChrospher RP select B, 125 x 4 mm id, 5 Jim, spectrometer, Bruker DRX 600 probe head, 4 mm z-gradient LC probe, active volume 120 a1 eluents, acetonitrile (A) and D2O (B) gradient, t = Omin A/B (40/60), t = 8 min A/B (70/30) at a flow rate of 1.0 ml/min and t = 80 min A/B (70/30) at a flow rate of 0.1 ml/min...

Acidic preservatives are the most widely used for oral preparations, such as the p-Hydroxybenzoic acid esters and salts of benzoic acid. These are adequately soluble in aqueous systems and possess both antifungal and antibacterial properties. Methyl and propyl p-hydroxybenzoic acid are often used together in a 10 1 ratio. Concomitant use of multiple esters makes possible a higher total preservative concentration owing to the independent solubilities of each and, according to some researchers, maximizes the antimicrobial effect. 

Aalto TR, Firman MC, Rigler NE. p-Hydroxybenzoic acid esters as preservatives I uses, antibacterial and antifungal studies, properties and determination. ] Am Pharm Assoc (Sci) 1953 42 449-457. 

Kamada A, Yata N, Kubo K, Arakawa M. Stability of p-hydroxybenzoic acid esters in acidic medium. Chem Pharm Bull 1973 21 2073-2076. 

Aoki M, Kameta A, Yoshioka I, Matsuzaki T. Application of surface active agents to pharmaceutical preparations I effect of Tween 20 upon the antifungal activities of p-hydroxybenzoic acid esters in solubilized preparations [in Japanese]. / Pharm Soc Jpn 1956 76 939-943. 

Lehner SJ, Muller BW, Seydel JK. Interactions between p-hydroxybenzoic acid esters and hydroxypropyl-P-cyclodextrin and their antimicrobial effect against Candida albicans. Int J Pharm 1993 93 201-208. 

Matthews C, Davidson J, Bauer E, et al. p-Hydroxybenzoic acid esters as preservatives II acute and chronic toxicity in dogs, rats and mice. / Am Pharm Assoc Sci) 1956 45 260—267. 

W G Tammilehto S and Buchi J, p-Hydroxybenzoic acid esters (Nipagins). I. Physicochemical properties, Pharm. Acta Helv., 43, 726-738 (1968). 

Econol Poly(p-hydroxybenzoic acid ester) Sumitomo Chem. 

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