Benzoic acid, crystallization solubility

The solvent is chosen so that the desired product is readily soluble in it at high temperatures, but only sparingly soluble at lower temperatures so that crystals form as the hot mixture cools down. The solvent used to recrystallise benzoic acid is water. 

Benzoic Acid occurs as white crystals, scales, or needles. It begins to sublime at about 100° and is volatile with steam. One gram is soluble in 275 mL of water at 25°, in 20 mL of boiling water, in 3 mL of alcohol, in 5 mL of chloroform, and in 3 mL of ether. It is soluble in fixed and in volatile oils and is sparingly soluble in hexane. 

As a consequence of the close-packing principle, chemically different molecules with similar shape and volume should have identical crystal structures [27]. Substances forming mixed crystals must be isomorphous (i.e., not only must they have an identical space group and the same number of molecules, but also a similar molecular packing), otherwise there will be a discontinuity in their solubility curve [5]. For example, benzoic acid and isopropylbenzene, in spite of the similarity in... 

IV.41 BENZOATES, C6H5COO" OR C7H502 Solubility Benzoic acid, C6H5COOH or H.C7H502, is a white crystalline solid it has a melting point of 121°. The acid is sparingly soluble in cold water, but more soluble in hot water, from which it crystallizes out on cooling it is soluble in alcohol and in ether. All the benzoates, with the exception of the silver and basic iron(III) salts, are readily soluble in cold water. 

Saccharin was discovered in 1879 by Remsen and Fahlberg. It is only slightly soluble in cold water, but is soluble in hot water, acetone, alcohol or ether. From acetone it crystallizes in beautiful crystals. It is a valuable medicinal substance as it can be used for its sweetening effect in food, by persons who have the disease known as diabetes and who are unable to use cane sugar, and only a minimum of any carbohydrate food. It does not possess any nutritive value, however. It is also used as a food preservative, but its use is restricted or prohibited by most pure food laws. It is interesting that only the or//fo-sulph-amine benzoic acid yields such a sulphinid anhydride. The para compound, on heating, yields other products. 

Curve 4 exhibits very steep solubility. Yield is obtained by cooling the feed solution. To prevent fines formation, the cooling must exactly follow the solubility curve. This is done automatically in batch crystallizers. Continuous crystallizers in series must have the crystallizer stage temperatures selected so as not to cross the solubility curve. Benzoic acid and DMT exhibit this type of solubility. 

The benzoic acid, which is neutral, is less soluble than the related anion. In fact, it is so insoluble that it precipitates out from the solution as white flaky crystals. This great difference in solubility may be used to advantage to purify benzoic acid. The benzoate anion can be extracted into an aqueous bicarbonate solution, leaving behind any neutral organic impurities. Then, after acidification, the free acid may be extracted into an organic solvent. This second extraction allows the acid to be separated from impurities that are soluble in water. 

Thermally stable copolymers of 3-(trimethylsiloxyl)- and 3,5-bis(trimethylsiloxyl)benzoyl chloride (4A) or 3-acetoxy- and 3,5-diace-toxy-benzoic acid (4B) were prepared with mole ratios of AB AB2 monomer ranging from 160-5.32 Polymers containing 10-20 mole % of branching monomers were insoluble in CHC13 but soluble in polar solvents, such as A,A-dimethylformamide (DMF) or a mixture of pyridine and benzene. Compared to the linear homopolymer of 3-hydroxy-benzoic acid, the branched polymer showed lower crystallinity and slower crystallization. There was an inverse linear relationship between percent crystallinity and the number of branches in the chain. Similarly, in an attempt to improve moldability and decrease anisotropy of rigid aromatic polyesters, 0.3-10 mole % of 1,3,5-trihydroxybenzene, 3,5-di-hydroxybenzoic acid, and 5-hydroxyisophthalic acid were copolymerized with p-hydroxybenzoic acid/terephthalic acid/4,4 -dihydroxy-diphenyl.33 The branched polymer showed a lower orientation and possessed improved flex properties. 

Cu(TpMe)2] prepared from the reaction of CuCl2 with K(TpMe) has been characterized by magnetic susceptibilities, fast atom bombardment and IR spectrometry, and X-ray single-crystal study.1 Cop-per(I) complexes containing water soluble phosphines, [Cu(TpMe)(L)] (L = 4- or 2-(diphenylphosphane)benzoic acid), have been characterized by IR in the solid state, and by NMR (JH and 31P 1H ) and electrospray mass spectroscopy in solution. Chemiluminescence technique was used to evaluate their superoxide scavenging activity.2... 

Benzoic acid, 5-(2,4-dichlorophenoxy)-2-nitro-, methyl ester Bifenox BRN 2170169 Caswell No. 561AA CCRIS 7158 5-(2,4-Diohlorophenoxy)-2-nitrobenzoic acid methyl ester MC-4379 Modown Modown 4 Flowable EPA Pesticide Chemical Code 104301 MC-4379 Methyl 5-(2,4-dichlorophenoxy)-2-nltrobenz-oate Modown, Selective herbicide used for control of annual broad-leaved weeds and some grasses in cereals, maize, sorghum, soybeans, rice and some other crops. Registered by EPA as a herbicide (cancelled). Yellow crystals mp = 84-86 poorly soluble in H2O (0.000035 g/100 ml), more soluble in MezCO (31.5 g/100 ml), chlorobenzene (44,3 g/100 ml), xylene (25.8 g/100 ml), EtOH (< 4 g/100 ml) slightly soluble in aliphatic hydrocarbons LDso (rat orl) > 6400 mg/kg, (mus orl) = 4556 mg/kg, (rbt der) > 20000 mg/kg LC50 (rat ihl) > 200 mg/l air, (duck, pheasant 8 day dietary) > 5000 mg/kg diet, (rainbow trout 96 hr.) = 0.87 mg/l, (bluegill sunfish 96 hr.) = 0.64 mg/l. Aventis Crop Science. 

Acetamido-2-methoxybenzoic acid methyl ester Amprol Plus (veterinary) Benzoic acid, 4-(acetylamino)-2-ethoxy-, methyl ester EINECS 200414-3 Ethopabate Ethyl pabate pancoxin. Coccidiostat, used in poultry, often as Amprol Plus, a combination with amprolium. Crystals mp = 148-149 Xm = 298, 267 nm (A l im 805,365) slightly soluble in H2O, more soluble in organic solvents. 

Benzoic acid, 4-(dimethylamino)-, ethyl ester EINECS 233-634-3 Ethyl 4-dimethylaminobenzoate Parbenate Speedcure EDB. UV photoinitiator. Crystals mp= 63-65" d = 1.0610 insoluble in H2O, soluble in organic solvents. Aceto Corp. Lambson Ltd. 

Beilstein Handbook Reference) AI3-00513 Benzoic acid, 2-hydroxy-, ethyl ester BRN 0907659 EINECS 204-265-5 o-(Ethoxycarbonyl)phenol Ethyl 2-hydroxybenzoate Ethyl o-hydroxybenzoate Ethyl salicylate PEMA No. 2458 Mesotol NSC 8209 Sal ether Sal ethyl Salicylic acid, ethyl ester Salicylic ether Salicylic ethyl ester Salotan. Used in perfumery has been used in veterinary medicine as a counter-irritant. Crystals mp = 45° bp = 231-234°, bpio = 150-151° d = 1,1326 Xm = 238, 305 nm (c = 13800, 6590, MeOH) insoluble in H2O, soluble in CCI4, very soluble in Et20, freely soluble in EtOH,... 

Beilstein Handbook Reference) AI3-00861 Benzoic acid, 3,4,5-trihydroxy-, methyl ester BRN 2113180 CCRIS 5567 EINECS 202-741-7 Gallic acid methyl ester Methyl 3,4,5-trihydroxybenzoate Methyl gallate Methylgallate NSC 363001. Used by ophthalmologists as an antiseptic in conjunctivifis. Crystals mp = 202 soluble in hot H2O, EtOH, MeOH, Et20. 

Beilstein Handbook Reference) AI3-04243 Benzoic acid, 4-methyl-, methyl ester BRN 1100609 p-Carbomethoxytoluehe CCRIS 6071 EINECS 202-784-1 HSDB 5327 Methyl 4-methylbehzoate Methyl p-methylbenzoate Methyl 4-toluate Methyl p-toluate Methyl p-toluenecarboxylate NSC 24761 p-Toluic acid, methyl ester. Crystals mp = 33.2° bp = 220° Xm = 238,281 nm (s = 14200, 557, MeOH) insoluble in H2O. very soluble in EtOH, Et20. 

Beilstein Handbook Reference) AI3-15626 Benzoic acid, 3-methyl- BRN 0970526 EINECS 202-723-9 m-Methylbenzoic acid m-Toluic acid m-Toluylic acid meta-Toluic acid NSC 2214. Used in manufacture of N,N-diethyl-m-toluamide, a broad-spectnim insect repellent. Crystals mp = 108.7° bp = 263° d 2 = i.054slightly soluble in H2O, CHCI3. very soluble in EtOH, Et20 slightly soluble in H2O, soluble in organic solvents. CK Witco Chem. Cap. CK Witco Chem. Ltd. MitsubisN Gas. 

Beilstein Handbook Reference), A13-15627 Benzoic acid, 4-methyl- BRN 0507600 p-Carboxytoluene Crithminic acid EINECS 202-803-3 4-Methylbenzoic acid NSC 2215 p-Methylbenzoic acid p-Toluic acid 4-Toluic acid p-Toluylic acid. An animal feed supplement used in agricultural chemicals. Crystals mp = 179.6° bp = 274-275° Xm = 236,280 nm (e = 13500, 614, MeOH) insoluble in H2O, slightly soluble In TEA, very soluble in EtOH, Et20, MeOH. Degussa-Huls Cap. National Starch Chem. UK Penta Mfg. 

HA (2-amino-3-hydroxy-benzoic acid) forms colourless crystals, slightly soluble (<1 mM) in water or aqueous solutions at physiological pH values. Owing to its amphoteric properties, the substance is readily soluble in both acidic and basic solutions. However, HA is easily autoxidised when dissolved in alkaline media. So relatively concentrated solutions should be prepared with the aid of diluted hydrochloric acid, where it is reasonably stable. HA does not show any light absorption in the visible range, whereas has a X,max of 297 nm (e 2496 Ivr cm 1) in the UV region, at pH 2. The substance is fluorescent, with A x 323 nm, A,em 414 at pH 6.4. 

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