Methyl p-chlorobenzoate

Treatment of methyl p-chlorobenzoate with an equivalent amount of commercial potassium silanolate 97 in abs. diethyl ether affords, after 4h, pure, anhydrous potassium p-chlorobenzoate in 84% yield and methoxytrimethylsilane 13 a. Trimethylsilyl trifluoroacetate reacts hkewise with sodium trimethylsilanolate 96 in THF to give sodium trifluoroacetate, in 98% yield, and hexamethyldisiloxane 7 [119] (Scheme 4.45). 

The intervention of an intermediate with the symmetry of a benzocyclopropenone (166, R = Cl) is also demanded by the formation of methyl p-chlorobenzoate in the photolysis of the lithio derivative 173 of the chlorosubstituted 3-p-tolylsulpho-nylamino-benzo-l,2,3-triazin-4-one128) ... 

Methyl ester, C H.ClOj, methyl p-chlorobenzoate, mp 44. Sodium salt, CjH4ClNa02, sodium p-chlorobenzoate. White, odorless, crystalline powder, freely sol in water. Ingredient of Microbin which also contains the ortho isomer. USE Sodium salt as a preservative. 

Benzoic m-Toluic (Benzoic acid, 3-methyl-] p-Toluic [Benzoic acid, 4-methyl-J 3,5-Dimcthylbcnzoic [Benzoic acid, 3,5-dimcthyl-] p-Chlorobenzoic [Benzoic acid, 4-chloro-] p-Bromobenzoic [Benzoic acid, 4-bromo-J Phthalic [ 1,2-Bcnzcncdicarboxylic acid] Toluene [Benzene, methyl-] (78) m-Xylene [Benzene, 1,3-dimethyl-] (82) />-Xylene [Benzene, 1,4-dimethyl-] (74) Mesitylene [Benzene, 1,3,5-trimethyl-] (82) p-Chlorotolueno [Benzene, l-ehloro-4-methyl-] (94) p-Bromotolucnc [Benzene, l-bromo-4-methyl-] (94) o-Xylene [Benzene, 1,2-dimethyl-] (64)... 

Diazomethane In a distillation flask equipped with an distillation funnel and a cooler, place a solution of 5 g of potassium hydroxide in 8mL of water and 25 mL of ethanol. Warm the distillation flask to 65 °C in a water-bath. Add a solution of 21.5g (0.1 mol) of A-methyl-lV-nitroso-p-toluenesulfamide in 130 mL of diethyl ether through the instillation funnel in 5 min. If the distillation funnel becomes empty, pour 20 mL of diethyl ether into the funnel, and distill it gradually. Continue distillation until the distilled ether solution becomes colorless. About 3 g of diazomethane is contained in the whole resultant ether distillate. Caution these procedures should be conducted in a laboratory hood Orbencarb, methyl 2-chlorobenzylsulfone (I), 2-chlorobenzoic acid (II), methyl 2-chlorobenzoate analytical standard materials (Ihara Chemical Industries Co., Ltd) Orbencarb and I standard solution for gas chromatography 1.0 qgmL in acetone Methyl 2-chlorobenzoate standard solution for gas chromatography 0.1 qgmL" in n-hexane... 

According to the other scheme, phenylhydrazone (3.2.46) undergoes cyclization in the presence of the same p-chlorobenzoic acid chloride, during which acylation of hydrazone and its cyclization into methyl ester of 5-methoxy-2-methyl-2-(p-chlorobenzoyl)-3-indoly-lacetic acid (3.2.52) simultaneously take place. The resultiug product is further hydrolyzed by au alkali to give indomethaciu (3.2.51) [113,114]. 

By analogy, flash vacuum pyrolysis of a p-chlorobenzoate ester (378, Ar=4-C1C6H4) (90TL1487) produced oxazole-4,5-xylylene (379), which could be trapped with S02 to give adduct (381). The unstable intermediate also gave a Diels-Alder adduct (380) with methyl acrylate (for the similar reactions see Section 3.3.3.3.3). 

Flak and Schaber (5,62) used reverse-phase HPLC for the quantitative and simultaneous determination of benzoic acid and sorbic acid, as well as 4-hydroxybenzoic acid, salicylic, 5-nitrofurylacrylic, and p-chlorobenzoic acid and the EsHBA (methyl, ethyl, propyl) in wines and beverages. The first five compounds can be determined by isocratic elution from a Clg column using 0.12 M acetate, pH 3.8 acetonitrile (85 15), and all may be separated with gradient elution (increasing acetonitrile from 10 to 60%, with a simultaneous decrease of the pH of the acetate buffer from 3.9 initially to 3.3). 

Methyl esters may be prepared by reaction of the aromatic carboxylic acid with diazomethane (cf. Section 4.2.25, p. 433) or, more conveniently, by reaction with a boron trifluoride-methanol reagent. The latter procedure is illustrated by the preparation of methyl m-chlorobenzoate and dimethyl terephthalate (Expt 6.164). t-Butyl esters may be prepared by conversion of the acid into an N-acylimidazole by reaction with N,N -carbonyldiimidazole, followed by reaction with t-butyl alcohol in the presence of DBU62 (Expt 6.165). 

Place 9.4 g (0.06 mol) of m-chlorobenzoic acid and 66 ml (0.12 mol) of boron trifluoride-methanol complex (14% w/v of BF3 Section 4.2.8, p. 421) in a 250-ml round-bottomed flask. Heat the mixture under reflux on an oil bath for 2 hours, cool and pour into about 250 ml of saturated sodium hydrogen carbonate solution. Extract the organic product with three 50 ml portions of ether, dry the ethereal extract over magnesium sulphate and evaporate on a rotary evaporator. Distil the residue under reduced pressure and collect the methyl m-chlorobenzoate as a colourless liquid of b.p. 63 °C/3mmHg the yield is 9.3 g (91%). 

CD studies of pyranosides derivatized as tribenzoates have shown that the pairwise couplings are additive. For example in the 2,3,4-tris-p-chlorobenzoate of methyl-a-D-manno-pyranoside there are three pairwise couplings (2,3), (3,4) and (2,4).[2] As shown in Figure 35, each of the three is predicted to exhibit a (-) exciton chirality, and thus (assuming additivity) the net CD is expected to correspond to a (-) exciton chirality. This is, in fact, observed. In other sugars, where some of the individual couplets may have a (+) exciton chirality, and others a (-) exciton chirality, the net predicted exciton CD would be determined by the magnitudes and signs of each of the component couplet CEs. Nakanishi et al have shown this approach to be exceptionally reliable. [37]... 

Figure 35. (a) Stable chair conformation of methyl a-D-mannopyranoside and (b) exciton coupling CD Cotton effects of its 2,3,4-tris-p-chlorobenzoate. (c) Pairwise couplings of the 2,3,4-tri-p-chlorobenzoate with (-) chiralities noted for each. 

This procedure has been modified to become an effective catalytic procedure in which iV-methyl-moipholine A -oxide is used as the secondary oxidant. In this manner, ( )-stilbene has been converted into (+)-r/irco-hydrobenzoin (55% yield after two reciystallizations, >99% ee) on a one molar scale, by treatment with osmium tetroxide (0.002 mol equiv.) and iV-methylmoipholine 1 -oxide (1.2 mol equiv.) in aqueous acetone in the presence of dihydroquinidine p-chlorobenzoate (0.134 mol equiv.). The latter compound can be recovered in 91% yield. 

C—O—CHCH2CH3 ib) Cl Ans. (a) s-Butyl p-chlorobenzoate, ib) p-chlorophenyl 2-methyl butanoate... 

---