Benzoic acid esters from

Semmler and Liao have examined the solid body isolated from Manila elemi oil by Schimmel Co. This was found to be a sesquiterpene alcohol, CjgHjgO, which has been named elemol. It was purified by converting it into its benzoic acid ester, from which the cohol was prepared in a pure state by hydrolysis. It has the following characters —... 

The principal low-level impurity was later identified to be the keto acid produced by oxidation of the ketoaldehyde. A very small amount of the benzoic acid resulting from hydrolysis of the methyl ester could also be detected. 

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

Which of the two is the cis form and which the trans form has not been determined. A third cinnamic acid, viz., iso-cinnamic acid, is also known, but the constitution of it has not been established. Cinnamic acid is found in nature in the resin storax both as the free acid and as the cinnamic alcohol ester, styrin. It is also found in Peru and Tolu balsams as the free acid and as the benzyl alcohol ester, the benzoic acid ester of benzyl alcohol being present also. Thus benzyl alcohol, benzoic acid, cinnamic alcohol and cinnamic acid are all constituents of esters present in these plant resins. Allo-cinnamic acid, the geometric isomer, is obtained from coca leaves from which the alkaloid cocaine is also obtained (p. 896). When cinnamic acid is heated with lime it loses carbon dioxide and yields the unsaturated side-chain hydrocarbon st3rrene, or phenyl ethylene, CeHs—CH = CH2. On reduction it yields first cinnamic aldehyde, found in oil of cinnamon (p. 842) and then cinnamic alcohol. Both cinnamic acid and allo-cinnamic acid yield anhydrides. 

One year later, in 1934, Vavon and co-workers [5] determined the relative reactivities of Grignard reagents with a different type of substrates benzoic acid esters. Steric requirements played a role when the alcohol component of the ester was changed from primary, to secondary, to tertiary the relative rates of reactions of ethylmagnesium bromide were 400 40 1, respectively. The relative rates of reaction of ethyl-, isopropyl-, n-butyl-, and phenylmagnesium bromide with ethyl benzoate decreased in this order. The reaction with rert-butylmagnesium chloride was reported to be extremely slow."... 

G) Hydrolysis of Esters. Place 2 ml of ethyl or methyl benzoate 3.nd 10 ml of 10 per cent sodium hydroxide solution in a test tube provided with a micro condenser. Heat in a water bath for 20-30 minutes until the ester layer disappears. The solution contains the alcohol and the sodium salt of the acid. If it is desired to separate the alcohol, the liquid is distilled until 5 ml of distillate is collected otherwise, the solution is cooled, and acidified with hydrochloric acid. Benzoic acid separates from the solution. The crystals are filtered and dried. 

The cr value alone can, of course, be used to understand the mechanism of those reactions which do not come under the ambit of cj+ and u values. For instance, the base hydrolysis of a benzoic acid ester may take two different pathways (a) nucleophilic attack of hydroxide ion on the carbonyl carbon to result in a tetrahedral intermediate, in a rate determining step, followed by its collapse into carboxylic acid or (b) nucleophilic attack of hydroxide ion on the alkyl carbon of the ester function, leading to the formation of the carboxylate directly. Since the carbonyl carbon is closest to the ring, the effect of a substituent felt by it must be much larger than the effect felt by the alkyl carbon. Hence, the rate of hydrolysis will be expected to increase much more in the former instance than in the latter with the increase in the substituent s a value. This is indeed the case as evident from the a versus rate constant k given in Table 3. The large increase in the rate of hydrolysis with the increase in cr could be justified only if the tetrahedral pathway is involved. The correlation of cr with log k is linear as seen from the plot in Fig. 5. 

Cocaine This drug, which has become such a pariah in our society, is the prototype for the local anesthetics. It is one of the success stories as evidenced by the wide variety of local anesthetics that have been made free of any abuse potential. Indeed, the structure of procaine, which is a simple benzoic acid ester, illustrates how the pharmacophore moiety can be abstracted from a more complex natural product. 

Many cellulose derivatives form lyotropic liquid crystals in suitable solvents and several thermotropic cellulose derivatives have been reported (1-3) Cellulosic liquid crystalline systems reported prior to early 1982 have been tabulated (1). Since then, some new substituted cellulosic derivatives which form thermotropic cholesteric phases have been prepared (4), and much effort has been devoted to investigating the previously-reported systems. Anisotropic solutions of cellulose acetate and triacetate in tri-fluoroacetic acid have attracted the attention of several groups. Chiroptical properties (5,6), refractive index (7), phase boundaries (8), nuclear magnetic resonance spectra (9,10) and differential scanning calorimetry (11,12) have been reported for this system. However, trifluoroacetic acid causes degradation of cellulosic polymers this calls into question some of the physical measurements on these mesophases, because time is required for the mesophase solutions to achieve their equilibrium order. Mixtures of trifluoroacetic acid with chlorinated solvents have been employed to minimize this problem (13), and anisotropic solutions of cellulose acetate and triacetate in other solvents have been examined (14,15). The mesophase formed by (hydroxypropyl)cellulose (HPC) in water (16) is stable and easy to handle, and has thus attracted further attention (10,11,17-19), as has the thermotropic mesophase of HPC (20). Detailed studies of mesophase formation and chain rigidity for HPC in dimethyl acetamide (21) and for the benzoic acid ester of HPC in acetone and benzene (22) have been published. Anisotropic solutions of methylol cellulose in dimethyl sulfoxide (23) and of cellulose in dimethyl acetamide/ LiCl (24) were reported. Cellulose tricarbanilate in methyl ethyl ketone forms a liquid crystalline solution (25) with optical properties which are quite distinct from those of previously reported cholesteric cellulosic mesophases (26). 

Ethyl or longer-chain phenyl ethers, in addition, would produce an ion of m/z 94 (C6H60+ ) via McLafferty-type rearrangement [reaction (6.29)]. The ion of m/z 93 (C6H7N+) is also prodnced from ionized 2-alkyl and 4-alkylpyridines via the McLafferty rearrangement. The m/z 105 ion (CeHsCO" "), which is produced via a-cleavage, is evidence for the presence of phenyl ketones and esters and amides of benzoic acids. Esters of benzoic acids will also produce a characteristic ion of m/z 122 as a result of the McLafferty rearrangement ... 

The simplest aromatic carboxylic acid is benzoic acid (8-72), which is relatively widespread in plant materials, mainly as 1-O-benzoyl-P-D-glucopyranose (see Section 4.3.3.3), but both compounds are non-volatile polar substances that do not have any impact on food flavour. In essential oils, benzoic acid is found in the form of flavour-active esters. Benzoic acid arises from cinnamic acid or cinnamoyl-CoA through side-chain shortening by a C2 unit. Its content in fruits and vegetables is generally very low, at around 0.05%. In cranberries it is present predominantly as 6-O-benzoyl-P-D-glucopyranose, known as vaccinin (see 4-92), in an amount of around 0.2%. Free benzoic acid is also present in a very small amount (about 0.0015%) in yoghurts where it results from hippuric acid hydrolysis. It is often also added to foods as a preservative. A typical example of a preserved product is table mustard, where concentrations of benzoic acid typically reach 1000 mg/kg. 

Gray s group also prepared the propanoate of (2-hydroxypropyl)cellulose (PPC or C3PC) from the esterification reaction of HPC (Mw = 100,000 g/mol) and propionyl chloride or propionic anhydride in acetone (Tseng et al. 1982). The appearance and behavior of the polymer is similar to APC, however this ester displayed iridescent colors at room temperature. In the same year (Bhadani and Gray 1982), the synthesis of the benzoic acid ester of HPC (BzPC) from the reaction of the aromatic benzoyl chloride with HPC in pyridine was described. The polymer showed a thermotropic liquid crystalline phase below 160 °C. Benzoic acid ester of HPC was fractionated from acetone solution by precipitation with methanol-water and polymers with different molecular weights were obtained (Bhadani et al. 1983). 

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