Benzoic acid ester compounds

Chemically stable benzoic acid ester compounds and biphenyl-based ferroelectric liquid crystal have been synthesized as well. The spontaneous polarization is relatively low in these two-ring systems [17], but very interestingly, the... 

This point is well-illustrated by the data of Table 19, which show the effect of methyl substituents on the rate coefficients for methyl ester formation from benzoic acid. The compounds fall naturally into three classes. Those with no ortho substituent react 3-4 times as fast as those which have one orthomethyl group, while 2,6-dimethylbenzoic acid, the only compound with two orf/io-substituents, did not give the ester at a measurable rate. 

C-Acylations of C,H-acidic compounds have also been realized on insoluble supports. The few examples that have been reported include the C-acylation of support-bound ester enolates with acyl halides [9], Claisen condensations of polystyrene-bound ketones with benzoic acid esters, the C-acylation of nitriles with acyl nitriles or anhydrides, and the C-acylation of phosphonates with acyl halides (Entries 5-9, Table... 

Patent Compounds Derived from Benzoic Acid Esters, Composition... 

Similarly to CDMA and II, and in contrast to CTMA, the LIF excitation spectra for the other molecules considered (i.e., ABN [86, 92b], EIN [92b], 4-dialkylamino derivatives of pyrimidine (except VIII) [90] and benzoic acid esters, XI and XII [88, 91, 94]) show the characteristic pattern of low-frequency vibrations (Table 1). Similar patterns have been analyzed for alkylbenzenes and toluenes [111], fluorotoluene [112, 113a,b], m-cresol [113c], toluidines [113d] and dialkylanilines [87a, 114] in terms of the internal rotation of the methyl groups, torsion of the dialkylamino group and inversion. The precise nature of the vibrations active in the LIF spectra of the considered compounds is not yet clear, but it is most probably associated with torsion and inversion of the dialkylamino group [86, 87, 88b, 90c]. The lowest... 

The factor 2.48 puts a on the same scale as Hammett s er, and the k0 values are rate constants for acid and base hydrolysis of acetic acid esters (i.e., R is a methyl group in the reference compound). Usually R is an ethyl or methyl group, but in many cases the rate constants do not depend on the nature of R. Equation 8 is based on the fact that acid hydrolysis rates of substituted benzoic acid esters are only slightly affected by the nature of the substituent, but acid hydrolysis rates of aliphatic esters are strongly affected by substituents. These effects were taken to be caused by steric factors thus log(/c//c0)acid defines s. It is reasonable to assume that steric factors affect base-catalyzed rates in the same way. Substituent effects on base hydrolysis of aliphatic compounds are composed of both polar and steric effects, and subtraction of the latter yields a measure of the former. The parameter a is important because it allows one to evaluate substituent effects on aliphatic reaction rates by a formula analogous to the Hammett equation, or by a bivariate relationship, the Taft-Pavelich equation (Pavelich and Taft, 1957) ... 

Crude and refined oils are known to contain the following aromatic compounds aromatic and polynuclear aromatic hydrocarbons (PAHs), phenols and cresols, heterocyclics (such as pyridine, quinoline), benzoic acid, esters and ethers. Many are quite water-soluble (Table IV) and are expected to be found in the dissolved fraction. 

Taft equation. Taft (1956) has extended the Hammett-type correlation to aliphatic systems. Because steric effects of substituents in aliphatic systems cannot be ignored as they were for m- and / -substituted benzene compounds, Taft recognized the need to develop separate terms for the polar and steric effects for substituent constants. Based on the observation that the acid-catalyzed hydrolysis of meta- and para-substituted benzoic acid esters are only slightly affected by the electronic nature of the substituent group (p values are near 0), Taft concluded that the acid-catalyzed hydrolysis of aliphatic esters would also be insensitive to polar effects of substituent groups. Any effect on rate due to substituent groups could therefore be attributed to steric effects. Taft defined a steric substituent constant, E, by ... 

The use of a Hammett substituent constants in QSAR analyses has been prominent since the early studies by Hansch and Fujita (1964) in medicinal chemistry. The electron-withdrawing/releasing potency of substituents on an aromatic system has been formalized by the Hammett equation (Hammett, 1940). The relative reactivities among homologous series of compounds under defined conditions - for example, the logarithms of the rate and equilibrium constants for the hydrolysis of substituted benzoic acid esters (rate constant k) and the ionization constants (K) of the corresponding acids, were found to be linearly related ... 

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. 

D-Mannose-based alkyne, on similar clicking with 0-, m-, and / -substituted azido benzoic acid esters, afforded triazolyl glycoconjugates 65-67 (Scheme 6.17). These molecules were evaluated for their in vitro cytotoxic activity against seven cancer cell lines, where compound 65 showed increased activity (IC50 = 23.8 pM) than precursor 63 (ICgg = 93.2 pM) for CEM lymphoblasts. Also, deacetylation of compound 65 results in dramatic loss of activity [39]. 

Perfumes, Flavors, Cosmetics, and Soap. Many naturally occurring esters in essential oils and some synthetic esters are important fragrance and flavor compounds (61,62). They are used in perfumes, flavors, cosmetics, soaps, detergents, and air fresheners. Benzyl, butyl, ethyl, methyl, and phenyl esters of benzoic acid are used as flavors, perfumes, and food preservatives. Glyceryl 4-aminobenzoate [136-44-7] and 2-ethyUiexyl 4-dimethylaminobenzoate [21245-02-3] are used in cosmetic sunscreen preparations. Alkyl esters of 4-hydroxybenzoic acid, called parabens, have been used under various names for fungus infections of the skin, and as preservatives in lotions and creams (101). Soap and cosmetic fragrances use large amounts of amyl and benzyl saHcylate. Benzyl saHcylate [118-58-1] is also used in deodorant sprays. 2-Ethylhexyl saHcylate [118-60-5] and 2-ethylhexyl 4-methoxycinnamate [5466-77-3] are used in sunscreen formulations (102). 

It forms a characteristic benzoic ester, Cj HjgO. CO. CgH, melting at 54°. This is a useful compound for identifying menthol and may be obtained by heating menthol with the theoretical amount of benzoic acid, in a sealed tube to 170° excess of acid is removed by shaking with a boiling solution of sodium carbonate, and the ester is crystallised from alcohol. Menthol forms a phenylurethane, melting at 111° to 112°. 

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