Benzoic acid recrystallization

N-(4 Methoxyphenyl)-N-benzoyl-3-chloro-3-chloroantranlllc acid (4) 2 To ice cooled NaoEt (Irom 0 11 g Na and 10 mL ElOH) was added in rapid succession meltiyl 2 chloro 6 hydroxybenzoate 2 (0 86 g 4 7 mmol) and N (4 methoxyphenyl)benzimidyl chloride 1 (t 14 g 4 7 mmol) in EI2O (30 mL) The mixture was stirred vigorously and allowed to stand at rt tor 48 h The oily solid obtained alter evaporation was heated to 210 215°C lor 70 min under N2 The product was diluted with water (5 4 mL) ElOH (10 8 mL) and treated with 1 M NaOEt (5 4 mL) The mixture was relluxed lor 90 mm the solvent evaporated and the aqueous solution acldilied The dark oil was heated with NaOH (7 5 g) m EtOH (22 mL) Alter removal ol benzoic acid by exhaustive extraction with water the product was recrystallized Irom EtOH to give 0 36 g ol 4 (27 7%), mp 139 5 140 5°C... 

Pyridine has been phenylated with the following free-radical sources benzenediazonium chloride with aluminum trichloride the Gomberg reaction " phenylhydrazine and metal oxides A -nitroso-acetanilide dibenzoyl peroxide phenylazotriphenylmethane di-phenyliodonium hydroxide and electrolysis of benzoic acid. ° Although 2-phenylpyridine usually accounts for over 50% of the total phenylated product, each of the three phenyl derivatives can be obtained from the reaction by fractional recrystallization of the... 

A mixture of 10 g of 4-(2, 4 -difluorophenyl)-phenol and 27.2 g of potassium carbonate is exposed to carbon dioxide at 1,300 psi and 175°C. The dark mass obtained from this car-donation is then dissolved in 300 ml of water and 200 ml of methylene chloride and the two layers separated. The water layer is then extracted with 100 ml of methylene chloride and then acidified with 2.5 N hydrochloric acid. This mixture is then filtered and the cake dried in vacuo to yield 5.32 g of the crude product. The crude product is then recrystallized from benzene-methanol. An additional crystallization of this semipure material from benzene-methanol yields analytically pure 2-hydroxy-5-(2, 4 -difluorophenyl)-benzoic acid (MP 210°-211°C). 

The aqueous phase was rendered acid with concentrated hydrochloric acid (weak Congo red and the separated acid taken up in ether. The isolated crude acid was recrystallized from dibutyl ether, yielding colorless crystals of 4-[(2-methvl-1,2-dicarbobenzoxy-hvdra-zino)-methyl] -benzoic acid, which melted at 112°C. The so-obtained product was sufficiently pure for further reaction. 

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. 

Preparation of 2 -Amino-6 -diethylaminofluoran (74a). A mixture of 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid (0.1 mol), p-anisidine (0.1 mol), and concentrated sulfuric acid (100 g) was stirred at 50 °C for 24 h. After being cooled, the mixture was poured into water (500 ml), and made alkaline by 20% aqueous sodium hydroxide. The precipitate was filtered off, washed with water, dried, and then recrystallized from toluene to give 2 -amino-6 -diethylaminofluoran in 90% yield as an off-white powder, mp 213-215 °C. 

Preparation of 6 -Diethylamino-2 -n-octylaminofluoran (74d). To a solution of 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid (0.1 mol) in 98% sulfuric acid (150 g) was added p-n-octylaminoanisole (0.1 mol) in limited amounts, while the temperature was maintained not to rise above 30 °C. The resulting mixture was stirred at room temperature for 20 h, and poured into ice water (1000 ml). The resinous precipitate was collected by decantation, and then refluxed with a mixture of toluene (250ml) and 20% aqueous sodium hydroxide (100 g) for 1 h. The toluene layer was separated, washed with hot water, concentrated, and the residue recrystallized from isopropanol (100 ml) to give 6 -diethylamino-2 -n-octylaminofluoran in 75% yield as a white powder, mp 127-128 °C. 

I ve included 2532 (Benzoic acid, 2-acetamido) to show that you sometimes get a bonus. Here nd(aa) means you get needle-like crystals from acetic acid. Acetic acid (aa) is the recrystallization solvent (see Chapter 10, Recrystallization ), and you don t have to find it on your own. Thus, pa ye nd (al) means that pale yellow needles are obtained when you recrystallize the compound from ethanol. 

Addition of HC1 to the benzoic acid extract will produce huge amounts of white crystals. Get out the Buchner funnel and have a field day Collect all you want. But they won t be in the best of shape. Recrystallize them. ("Note This compound is insoluble in the aqueous recovery solution.)... 

Manufacture. ///-Hydroxybenzoic acid was first obtained by the action of nitrous acid on / -aminobenzoic acid (48). It is more conveniendy prepared by the sulfonation of benzoic acid with fuming sulfuric acid. The resulting ///-sulfobenzoic acid is mixed with salt and fused with caustic soda at 210—220°C. The fusion melt is dissolved in water and acidified with hydrochloric acid to precipitate the cmde product. Final purification is generally achieved by recrystallization from water. 

A reactor was charged with a benzoic acid-acrylic ether derivative (81 mmol), 2,5-dihydroxybenzaldehyde (37 mmol), 4-dimethylaminopyridine (22 mmol), and 200 ml of CH2CI2 and then treated with the dropwise addition of 1,3-dichlorohexylcarbodi-mide (81 mmol) dissolved in 100 ml of CH2CI2. After the addition the mixture was stirred at ambient temperature for 10 hours and a precipitate formed that was removed and the organic layer was washed with water, dried with MgSOzt, and concentrated. The residue was purified by column chromatography, recrystallized from ethanol, and 27 mmol of product isolated. 

To 3 parts of 3,5-diiodo-4-(3-iodo-4-hydroxyphenoxy)benzoic acid 10 parts of acetic acid anhydride was added and mixture was heated on oil bath for some hours. In the result of this reaction amorphous precipitate was obtained. After recrystallization from glacial acetic acid 2.4 parts of 3,5-diiodo-4-(3-iodo-4-acetoxyphenoxy)benzoic acid were obtained. 

The n-butyl 4-nitro-2-n-butoxybenzoate obtained was dissolved in 50% aqueous ethanol. To this solution was added 2 - 3 molecular equivalents of sodium carbonate, and the resulting mixture, was stirred under reflux for about 16 h. After the ethanol has been distilled off under reduced pressure, the remaining aqueous solution was diluted with water and made acidic with concentrated hydrochloric acid. The precipitated yellow solid was filtered, washed with water, dried in a vacuum oven at 90°C and recrystallized from ethyl acetate. There was thus obtained a 4-nitro-2-n-butoxy-benzoic acid (95.5% yield), melting point 120.9°-122.8°C (corn). 

Guanidinocaproic acid p-tosyl salt and thionyl chloride were mixed together to react at the room temperature. An endothermic reaction occurred and the caproic acid gradually dissolved. Then the reaction mixture was left standing for 1 to 2 h and was extracted with ether. The lower oily layer and the ether layer were separated from each other and the lower layer was repeatedly washed with ether. Then the oily substance (caproic acid chloride) was added with benzoic acid ethyl ester in tetrahydrofuran, and the mixture was stirred. After the mixture became a uniform solution, of pyridine were gradually added. An exothermic reaction occurred and an oily substance came to be separated in the lower layer. After the completion of the reaction, the oily substance was washed with water and then recrystallized from hot water once or twice. Thus 4-(6-guanidino-hexanoyloxy)-benzoic acid ethyl ester salt was obtained as white crystals. 

The solvents were then evaporated, yielding 4-[(2-methyl-l,2-dicarbobenzoxyhydrazino)-methyl]-benzoic acid isopropylamide as a yellow oil, which crystallized upon triturating with ether MP 90°-92°C. This product was then covered with 70 ml of a 33% solution of hydrogen bromide in glacial acetic acid, and then permitted to stand for 2 hours with occasional swirling, whereupon a thick slurry of crystals was formed. The precipitate was filtered off, washed with 20 ml of glacial acetic acid and finally with ether, yielding crystals of 4-[(2-methyl-hydrazino)-methyl]-benzoic acid isopropylamide hydrobromide, which after recrystallization from methanol/ether melted at 216°-217°C (dec.). 

Dilute sulphuric acid white, crystalline precipitate of benzoic acid from cold solutions of benzoates. The acid may be filtered off, dried between filter paper or upon a porous tile and identified by means of its melting point (121°). If the latter is somewhat low, it may be recrystallized from hot water. 

Ethyl 4,5-Dlbenzamldopent 4-enoate (2) Ethyl 3-imidazol-4(5)-ylpropanoate 1 (9.2 g, 54 rnnwl) in ElOAc (140 ml) was treated with benzoyl chloride (IS 7 g, 112 mmol) in ElOAc (40 mL) and 1M NaHCOs (380 ml) added simultaneously In 1 h under ice-cooling. The reaction mixture was stirred for 1 h, then a further portion olbenzoyichionde (15 7 g, 112 mmol) in EtOAc) and 1M NaHCOs (280 mL) was added in the same manner, followed by an additional portion of 1M NaHCOs (200 mL) The reaction mixture was stirred for 24 h, then the organic layer was separated, concentrated, and the residue dissolved in THF (300 mL) The THF solution was stirred with 10% NaHCOa (600 mL) for 24 h to decompose any N-lormyl intermediate and to remove benzoic acid Extraction with EtOAc, drying (Na2S04), solvent evaporation and recrystallization of the residue from EtOAc hexane afforded 16 24 g of 2 (84%), mp 128-129 C... 

The ester formed above is heated under reflux for 9 hours with 50 ml. of 48% aqueous hydrobromic acid. The reaction mixture is dissolved in 250 ml. of hot water and allowed to cool overnight. The precipitated benzoic acid is removed by filtration, and the filtrate is evaporated to dryness under reduced pressure. The solid residue is dissolved in 50 ml. of hot water, and the solution is brought to pH 6 (isoelectric point for leucine) with 6 i T ammonium hydroxide solution, after which 200 ml. of 95% ethanol is added. Cooling in the refrigerator for 36 hours allows precipitation of the amino acid. The yield is 6.3 g., or 78%. The product may be recrystallized from a mixture of water and ethanol. 

A mixture of 500 g. (4.10 moles) of benzoic acid and 1 kg. of 20% fuming sulfuric acid is heated gradually until a temperature of 210° is reached. The temperature of the mixture is held at 210° mtil a small test portion shows complete water solubility. This requires about 5 hours. The cooled mixture is poured into 2 1. of cold water and filtered if necessary the resulting solution is added to a mixture of 5 1. of boiling saturated sodium chloride solution and 150 g. of solid sodium chloride. The mixture is cooled, and the precipitated product is collected by filtration and washed with cold saturated sodium chloride solution. Recrystallization of the salt three times from saturated sodium chloride solution followed by drying at 100° gives a 90% yield of white needles of sodium w-carboxybenzenesul-fonate. 

Isolate the 2-naphthol from Flask 2 employing vacuum filtration on a Hirsch funnel (see Fig. 2 in Chapter 3) and wash it on the filter with a small quantity of ice water. Determine the weight of the crude product and then recrystallize it from boiling water. Similarly isolate, weigh, and recrystallize from boiling water the benzoic acid in Flask 1. The solubility of benzoic acid in water is 1.9 g/L at 0°C and 68 g/L at 95°C. 

Crude benzoic acid is purified by sublimation or recrystallization. 

The salt crystals of l-(S)-2 of 4-(2,5-diisopropylbenzoyl)benzoic acid 1 with (S)-phenylethylamine (S)-2 were prepared by recrystallization from a methanol solution ofboth components (Scheme 27.1a). The crystals underwent enantiospecific photocyclization on irradiation at >290 nm with a high-pressure mercury lamp through Pyrex glass under argon at 288 K to give a cyclobutenol (S)-4 in almost quantitative optical yield and 100% chemical yield [23]. 

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