Benzoic crystalline

To obtain crystalline perbenzoic acid, dry the moist chloroform solution with a little anhydrous sodium or magnesium sulphate for an hour, filter, and wash the desiccant with a little dry chloroform. Remove the chloroform under reduced pressure at the ordinary temperature whilst carbon dioxide is introduced through a capillary tube. Dry the white or pale yellow residue for several hours at 30-35° under 10 mm. pressure. The yield of crystalline perbenzoic acid, m.p. about 42°, which is contaminated with a little benzoic acid, is 22 g. It is moderately stable when kept in the dark in a cold place it is very soluble in chloroform, ethyl acetate and ether, but only shghtly soluble in cold water and in cold hght petroleum. 

Although the main uses for benzoic acid are as a chemical raw material, it also has numerous direct uses. Benzoic acid is used in substantial quantities to improve the properties of various alkyd resin coating formulations, where it tends to improve gloss, adhesion, hardness, and chemical resistance. Benzoic acid terminates chain propagation in alkyd resins (qv) and promotes crystallinity in the final product. 

Aromatic carboxyUc acids are produced annually in amounts of several million metric tons. Several aromatic acids occur naturally, eg, benzoic acid (qv), sahcyhc acid (qv), cinnamic acid (qv), and gaUic acids, but those used in commerce are produced synthetically. These acids are generally crystalline sohds with relatively high melting points, attributable to the rigid, planar, aromatic nucleus (see Phthalic acids). 

Aconitine produces an intense tingling sensation when a drop of a solution, 1 in 10,000, is applied to the tip of the tongue. It also gives a characteristic unstable, crystalline precipitate when a few drops of potassium permanganate solution are added to a solution of the alkaloid in dilute acetic acid. The formation of acetic acid when the alkaloid is heated dry, or of benzoic acid when it is hydrolysed by alkali, have also been suggested as identification tests. For the recognition of minute quantities a biological test is probably the best procedure. ... 

The acetyl group in aconitine may be eliminated in two other ways (a) by heating aconitine in sealed tubes with methyl alcohol, when methylbenzoylaconine, m.p. 210-1°, is formed, or (b) by heating the alkaloid at its melting-point, when pyraconitine, C32H43O9N, m.p. 167-5° (171°, Schulze), [a] ° — 112-2° (EtOH), is formed. The latter yields crystalline, laevorotatory salts, and on hydrolysis by alkalis affords benzoic acid and pyraconine, C2sH3gOgN, amorphous, [a]n — 91° (HgO), but yields a crystalline hydrochloride, B. HCl. 2-5H20, m.p. 154° (135°, Schulze), Md - 102° (HgO) (- 124-6°, Schulze). ... 

Neopelline, C2sH3305(0Me)3(NMe). 3H2O, was isolated from amorphous aconitine by Schulze and Berger. It is amorphous, and on alkaline hydrolysis furnishes acetic and benzoic acids with neoline, C2aH390gN, amorphous, but yielding a crystalline hydrobromide, needles, m.p. 210-5° (dec.), — 4-31°, and an acetyl derivative, the auri-... 

Delphinine, C34H47O9N (Walz) or C33H45O9N (J. and C.). The alkaloid crystallises in rhombs, or six-sided plates, m.p. 198-200°, [a]f ° + 25° (EtOH), shows mutarotation in alcoholic solution, and forms an acid oxalate, B. H2C2O4, m.p. 168° dry), a hydrochloride, B. HCl, m.p. 208-210°, and a monobenzoyl derivative, m.p. 171-3°. On alkaline hydrolysis it yields one molecule each of acetic and benzoic acids. The basic, hydrolytic product of this action is delphonine, C24H3g07N, which is amorphous, but can be distilled at a bath temperature of 140° and a pressure of 0-001 to 0-0001 mm. The brittle, possibly semi-crystalline resin so obtained, has m.p, 76-8° and [a]f ° - - 37-5 (EtOH). 

The caustic potash is melted with a small quantity of water in a siheror nickel crucible. The temperature of the mass is brought to 150, and the finely powdered benzil added. The benzil melts, and the mixture shortly changes to a solid mass of potassium ben/ilatc. The cooled melt is dissolved in water, and the alkaline solution acidified with hydrochloric acid, which precipitates the benzilic acid. The crystalline mass, which contains small quantities of benzoic acid, is separated from the mother-liquor and washed with cold water. It is then transferred to a porcelain basin, dissolved in hot water, and the solution boiled until the smell of bcn/oic acid has gone. On cooling, benzilic acid crystallises out, and is purified by a second crystallisation from hot water. 

Anisic acid is p-methoxy-benzoic acid, C, H. COCHg. COOH.. It is found in aniseed oil, and also in Tahiti vanillas. It is a crystalline body-melting at 184°. 

Figure 17 Differential scanning colorimetric trace of the liquid crystalline copolyester of 8-(3-phenyl hydroxy) octanoic acid and paro-hydroxy benzoic acid.

Benzoic acid (benzene carboxylic acid) is a white crystalline solid with a characteristic odor. It is slightly soluble in water and soluble in most common organic solvents. 

Subsequent to the development of the (salen)Cr-catalyzed desymmetrization of meso-epoxides with azide (Scheme 7.3), Jacobsen discovered that the analogous (salen)Co(n) complex 6 promoted the enantioselective addition of benzoic acids to meso-epoxides to afford valuable monoprotected C2-symmetric diols (Scheme 7.15) [26], Under the reaction conditions, complex 6 served as a precatalyst for the (salen) Co(iii)-OBz complex, which was fonned in situ by aerobic oxidation. While the enantioselectivity was moderate for certain substrates, the high crystallinity of the products allowed access to enantiopure materials by simple recrystallization. 

However, the hydrogen-bonded mesogens that are of most interest in the context of this article are those elaborated initially by Kato and Frechet in the early 1990s [24-33]. In this approach, a pyridine, which may or may not have liquid crystal properties, was hydrogen bonded with a 4-substituted benzoic acid to form a new species with its own, distinct mesomorphism. For example, complex 9 shows a SmA phase that persists to 238 °C (n = 2, m = 4), while its free component pyridine is nematic to 213 °C the component benzoic acid is also nematic (as the H-bonded dimer) to 147 °C (although note that the notional monomer would not be liquid crystalline). 

The regioselectivity of a Rhodococcus rhodochrous nitrilase has been demonstrated for the conversion of 5-fluoro-l,3-dicyanobenzene to 5-fluoro-3-cyano-benzoic acid [62]. The nitrilase was expressed in an Escherichia coli transformant, and a cell-free extract was employed as catalyst (0.14wt% cell-free extract) in 0.1m sodium phosphate buffer (pH 7.2) at 25 °C containing 0.18 m 5-fluoro-l,3-dicyanobenzene. After 72 h, the conversion was >98% and the reaction was stopped by addition of phosphoric acid (pH 2.4) to yield 5-fluoro-3-cyano-benzoic acid as a crystalline product (97% isolated yield). 

Ph-HQ/HQ/BB (50/50) is a crystalline polyarylate and its HDT is 297 °C. We found that copolymerization involving small amounts of the third unit (HBA) into this system could improve its crystallinity (Figure 19.13) and HDT finally, the HDT of the copolyarylate Ph - HQ/HQ/BB/p-hydroxy benzoic acid (HBA) (47.5/47.5/5) increased to above 300 °C. 

In the following we shall focus on heterogeneous acid-base reactions. One of the best known case studies is the reaction of crystalline benzoic acid with ammonia to form 1 1 ammonium salts [19, 20]. Crystalline p-chlorobenzoic anhydride reacts with gaseous ammonia to give the corresponding amide and ammonium salt [22] a similar reaction has been investigated in the case of optically active cyclopropanecarboxylic acid crystals [23]. 

Nitrosylsulfuric acid is used in making caprolactam from benzoic acid and in preparing many disperse azo dyes. Other apphcations are bleaching, maturing, dough-conditioning cereal products, and in preparing crystalline diazonium sulfates. 

Benzoic acid is ordinarily obtained as a feathery, light crystalline powder. Certain habit modifications can cause the material to exist as needles or as plates. 

When crystallized from an acetone-water mixture, benzoic acid is obtained as the crystalline needles shown in Figure 1 A. On the other hand, a mixture of needles and irregular crystalline solid is obtained from methanol-water mixtures (Figure IB). From pure water, aggregates of monoclinic crystals are obtained (Figure 1C). 

Benzoic acid is ordinarily obtained as a highly crystalline material, which aids in its purification and contributes to its use as a reference material. The x-ray powder diffraction pattern of benzoic acid was obtained on a Jeol JDX-3530 diffractometer system. The x-ray radiation was provided by copper target, operated at 40.0 kV and 30 mA. The powder pattern was obtained using a step angle of0.040 degrees 2-0, and each step was... 

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