C6H6

The 7i-orbitals of benzene, C6H6, may be modeled very crudely using the wavefunctions and energies of a particle on a ring. Lets first treat the particle on a ring problem and then extend it to the benzene system. 

Aryl 9-fluorenecarboxylates prepared from the phenol and the acid chloride (9-fluorenecaibonyl chloride, Pyr, C6H6, 25°, 1 h, 65% yield) can be cleaved by photolysis (hv, Et20 reflux, 4 h, 60% yield). The related aryl xanthenecarboxy-lates (i) were prepared and cleaved in the same way. ... 

From RCO2K CH3SCH2CI, Nal, 18-crown-6, C6H6, reflux, 6 h, 85-97% yield. ... 

Recrystd from MeOH or C6H6 containing a little EtOH. The phenylureido derivative has m 154°. [7 Chem Soc 461 1946.]... 

Aminosalicylic acid (5-amino-2-hydroxybenzoic acid) [89-57-6] M 153.1, m 276-280 , 283 (dec), pK 2.74 (CO2H), pK 5.84 (NH2). Cryst as needles from H2O containing a little NaHS03 to avoid aerial oxidation to the quinone-imine. The Me ester gives needles from C6H6, m 96°, and the hydrazide has m 180-182° (From H2O). [Fallab et al. Helv Chim Acta 34 26 1951, Shavel J Amer Pharm Assoc 42 402 1953.]... 

Benzeneazodiphenylamine (4-phenylazodiphenylamine) [28110-26-1] M 273.3, m 82, pK 1.52. Purified by chromatography on neutral alumina using anhydrous C6H6 with 1% anhydrous MeOH. The major component, which gave a stationary band, was cut out and eluted with EtOH or MeOH. [Hogfeldt and Bigeleisen J Am Chem Soc 82 15 I960.] Crystd from pet ether or EtOH. See Sudan I. 

Benzenedimethanol (1,2-bishydroxymethylbenzene) [612-14-6] M 138.2, m 61-64 , 63-64 , 64-65 , 65-66.5 , b 145 /3mm. Recrystd from C6H6, H2O, pet ether or pentane. It has been extracted in a Soxhlet with Et20, evaporated and recrystd from hot pet ether. Also dissolve in Et20, allow to evaporate till crystals are formed, filter off and wash the colourless crystals with warm pet ether or pentane. The diacetate has m 35 , 35-36 . [J Am Chem Soc 69 1197 1947, IR and UV J Am Chem Soc 74 441 7952.]... 

Benzoic acid [65-85-0] M 122.1, m 122.6-123.1, pK 4.12. For use as a volumetric standard, analytical reagent grade benzoic acid should be carefully fused to ca 130 (to dry it) in a platinum crucible, and then powdered in an agate mortar. Benzoic acid has been crystd from boiling water (charcoal), aq acetic acid, glacial acetic acid, C6H6, aq EtOH, pet ether (b 60-80 ), and from EtOH soln by adding water. It is readily purified by fractional crystn from its melt and by sublimation in a vacuum at 80. ... 

Biphenyl-4-carboxylic (4-phenylbenzoic) acid [92-92-2] M 198.2, m 228 , pK 5.66 (in 50% 2-butoxyethanol). Crystd from C6H6-pet ether or aq EtOH. 

Bromoisatin [87-48-9] M 226.0, m 245°(dec), 251-153°, 255-256°. Forms red prisms or needles from EtOH. The N-acetate crystallises as yellow prisms from C6H6, m 170-172°, and the N-methyl derivative form orange-red needles from MeOH, m 172-173°. [Chem Ber 47 360 1914, 53 1545 7920 Reel Trav Chim Pays-BasTi 197 1954 Tetrahedron Lett 215 1978.]... 

Dissolved in 20% NaOH, extracted with a small amount of C6H6, then steam distd, until clear. The soln was then cooled and acidified slightly with 15% H2SO4. The thiol was distd out, dried with CaS04 or CaCl2, and fractionally distd under N2 [Mathias and Filho J Phys Chem 62 1427 1958]. Also purified by pptn as lead mercaptide from alcoholic soln, with regeneration by adding dilute HCl to the residue after steam distn. All operations should be carried out in a fume cupboard due to the TOXICITY and obnoxious odour of the thiol. 

Carbazole-9-carbonyl chloride [73500-82-0J M 300.0, m 100-103 , 103.5-104.5 . Recrystd from C6H6. If it is not very pure (presence of OH or NH bands in the IR) dissolve in pyridine, shake with phosgene in toluene, evaporate and recrystallise the residue. Carry out this experiment in a good fume cupboard as COCI2 is very TOXIC, and store the product in the dark. It is moisture sensitive. The amide has m 246.5-247 , and the dimethylaminoethylamide hydrochloride has m 197-198 . [Weston et al. J Am Chem Soc IS 4006 1953.]... 

Chloromethyl anthracene [24463-19-2] M 226.7, m 141-142° dec, 141-142.5°. If it is free from OH in the IR then recryst from hexane- C6H6 or C6H6 as needles. If OH is present then some solvolysis has occurred. In this case treat 8.5g with SOCI2 (4.8g) in dioxane (60mL) and reflux for 5h, then evaporate to dryness and wash the residue with cold and recrystallise. With KI/Me2CO it forms the iodomethyl... 

---