Benzoic acid, crystallization oxidation

CgHgO, PhCH = CHCOiH. Colourless crystals. Decarboxylales on prolonged heating. Oxidized by nitric acid to benzoic acid. Ordinary cinnamic acid is the trans-isomer, m.p. 135-136 C on irradiation with u.v. light it can be isomerized to the less stable cis-isomer, m.p. 42" C. 

Prepare a mixture of 30 ml, of aniline, 8 g. of o-chloro-benzoic acid, 8 g. of anhydrous potassium carbonate and 0 4 g. of copper oxide in a 500 ml. round-bottomed flask fitted with an air-condenser, and then boil the mixture under reflux for 1 5 hours the mixture tends to foam during the earlier part of the heating owing to the evolution of carbon dioxide, and hence the large flask is used. When the heating has been completed, fit the flask with a steam-distillation head, and stcam-distil the crude product until all the excess of aniline has been removed. The residual solution now contains the potassium. V-phenylanthrani-late add ca. 2 g. of animal charcoal to this solution, boil for about 5 minutes, and filter hot. Add dilute hydrochloric acid (1 1 by volume) to the filtrate until no further precipitation occurs, and then cool in ice-water with stirring. Filter otT the. V-phcnylanthranilic acid at the pump, wash with water, drain and dry. Yield, 9-9 5 g. I he acid may be recrystallised from aqueous ethanol, or methylated spirit, with addition of charcoal if necessary, and is obtained as colourless crystals, m.p. 185-186°. 

Benzoic Acid. Ben2oic acid is manufactured from toluene by oxidation in the liquid phase using air and a cobalt catalyst. Typical conditions are 308—790 kPa (30—100 psi) and 130—160°C. The cmde product is purified by distillation, crystallization, or both. Yields are generally >90 mol%, and product purity is generally >99%. Kalama Chemical Company, the largest producer, converts about half of its production to phenol, but most producers consider the most economic process for phenol to be peroxidation of cumene. Other uses of benzoic acid are for the manufacture of benzoyl chloride, of plasticizers such as butyl benzoate, and of sodium benzoate for use in preservatives. In Italy, Snia Viscosa uses benzoic acid as raw material for the production of caprolactam, and subsequendy nylon-6, by the sequence shown below. 

The synthesis of 1 -benzothiepin 1 -oxide (23) can be achieved via complex formation with tricarbonyl iron, and quantitative oxidation of the coordination compound 22 with 3-chloroperoxy-benzoic acid. Subsequent irradiation at — 50 C provides 23, which crystallized as yellow needles after low-temperature (-40 C) chromatography, and was characterized by 1H NMR spectroscopy at — 30 C23 before loosing sulfur within one hour at 13°C to give naphthalene. 

The recovery and purification of benzoic acid from a liquid-phase toluene oxidizer may involve distillation alone or it may involve a combination of distillation followed by extraction and crystallization. 

In either case, the initial distillation involves separating toluene and any material lower boiling than benzoic acid and recycling those low boilers to the toluene oxidizer. The benzoic acid and higher boiling fractions are then distilled and/or subjected to an extraction and crystallization process to... 

Although the motion of protons does not lead to electrical conduction in the case of benzoic acid, electronic and even ionic conductivity can be found in other molecular crystals. A well-studied example of ionic conduction is a film of polyethylene oxide (PEO) which forms complex structures if one adds alkaline halides (AX). Its ionic conductivity compares with that of normal inorganic ionic conductors (log [cr (Q cm)] -2.5). Other polymers with EO-units show a similar behavior when they are doped with salts. Lithium batteries have been built with this type of... 

Recent model studies strongly support the proposed mechanism. The first crystal structures of Fe(II) complexed to benzoylformate show that an a-keto acid can coordinate to the iron as either a monodentate or didentate ligand [236]. Exposure of these [Fe(II)(L)(bf)]+ complexes (L = tmpa or 6-Me3-tmpa) to 02 results in the quantitative conversion of benzoylformate to benzoic acid and C02, modeling the oxidative decarboxylation reaction characteristic of this class of enzymes. As with the enzymes, the use of 1802 in the model studies results in the incorporation of the label into the benzoate product. For [Fe(6-Me3-tmpa)(bf)]+, the rate of the oxidative decarboxylation increases as the substituent of the benzoylformate becomes more electron-withdrawing, affording a Hammett p of +1.07. This suggests that the oxidative decarboxylation involves a nucleophilic attack, most plausibly by the iron-bound 02, on the keto carbon of benzoylformate to initiate decarboxylation as proposed in Figure 27. 

When nine moles of phenyllithium in ether acted upon tetraacetyl-glucosyl chloride, the reaction mixture being subsequently decomposed with water, four products resulted. From the ether layer a quantitative yield of methyldiphenylcarbinol was recovered. Acetylation of the residue from the water layer, followed by fractional crystallization led to two crystalline substances and a residual sirup. The first crystalline product was (tetraacetyl-j3-D-glucopyranosyl)benzene (IV). The second m. p. 142-143°, [a]o24 — 2.3° (chloroform), appeared to be isomeric with IV. It oxidized to benzoic acid and deacetylated to give a sirup which consumed two moles of periodate with liberation of one mole of formic acid. While these properties are to be expected for a structure related to IV, this substance differed from both of the anomeric (tetraacetyl-n-glucopyranosyl)benzenes, nor did it appear to be a mixture of them. Its exact constitution is not yet known. 

The variation of the composition of benzoic acid, thm obtained, from that which Berzelim foxmd by the analysis of the benzoate of lead, earned m at first to niistnist our own analysis. Upon ncar inspection however, we found it necessary to admit, that the cause of the difference between the two analyses should be sought in the composition of the salt analyzed by Berzelius, We therefore undertook the analysis of the acid united to a base, and chose the benzoate of silver because of the facility with which it is obtained pure and crystallized, and because the oxide of silver shews but little dispmi-tion to form compounds. 

In vain did I endeavor to separate water from the benzoic acid, ° by saturating the crystallized acid with a given quantity of oxide of lead, and therefore could not infer the presence of water of crystallization this analysis farther gave four atoms of oxygen, although I had previously foimd by analysis of the salt of lead that the acid in it saturated three times as much of the oxide as in the neutral benzoate, I was therefore induced since the results did not correspond, to reject this analysis of the crystallized acid. 

Benzoic Ether. A colorless oil liquid, slightly heavier than water, aromatic in taste and odor. It boils at 410 Fahr It is prepared as follows Take 4 parts 90 per cent, alcohol, 2 parts crystallized benzoic acid, and 1 part concentrated muriatic acid distill them together, and, as soon as the product turns milky when mixed with water, change the receiver and collect the subsequent distillate add water to it, decant the ether from the surface of the water, and boil it with water and a little oxide of lead (to separate the benzoic acid) lastly, free it from water by allowing it to stand over chloride of calcium. Benzoio ether is also called benzoate of ethyl. 

Phenylacetic acid crystallizes in lustrous plates and melts at 76°. It is converted by oxidizing agents into benzoic acid, whereas the isomeric toluic acids are converted into phthalic acids —... 

The chlorobenzene processes for the production of phenol have lost then-importance since the 1970 s. Occasionally, the toluene oxidation process, also developed by Dow is still used. In the first stage of this process, toluene is oxidized to benzoic acid with air in the liquid phase at 150 to 170 °C and 5 to 10 bar, in the presence of cobalt salts, with 90% selectivity. By-products are methylbiphenyls, benzyl alcohol, benzaldehyde and esters. Following the purification of the crude product by distillation or crystallization, the benzoic acid is transformed into phenol in the presence of copper (II) salts with air and steam at 230 to 250 °C, and 2 to 10 bar, by way of the intermediate compounds copper benzoate, benzoyl-salicylic add and phenyl benzoate. The recovered crude phenol is refined by distillation. The molar yield of phenol is around 85 to 90%. 

---