W-Chlorobenzoic acid

Thus o-hydroxyphenyl-llthium cannot be obtained from o-bromophenol and lithium but, under proper conditions, o-bromophenol reacts with n-butyl-lithium to give a good yield of the lithium salt of o-hydroxyphenyl-hthium. An interesting application is to the preparation from m-bromochlorobenzene and M-butyl-lithlum of w-chlorobenzoic acid—an expensive chemical ... 

In a recent study, reaction of chiral allenamides 54 with m-chloroperbenzoic acid (m-CPBA) led to an epoxidation and subsequent ring opening by w-chlorobenzoic acid [19] The resulting a-keto aminals 55 were obtained with high diastereoselectiv-ity (Scheme 17.19). 

The oxidation of dienyl enolsilanes to the corresponding a-hydroxy ketones has also been developed and explored by Rubottom.19 For example, diene 37 was cleanly converted to ketone 38 under standard conditions. As expected, high selectivity for oxidation of the more electron-rich double bond was observed. As illustrated by the conversion of 37 to 39, acylation of the crude alcohols was achieved in high yields after removal of w-chlorobenzoic acid and the hexane solvent employed for the oxidation. 

In a follow-up study [34] it was discovered that the condensation of cyanothioacetamide with ethyl 2-ethoxymethylene-3-oxobutanoate in the presence of piperidine in fact gave a 41 % yield of 3-cyano-5-ethoxycarbonyl-6-methylpyridine-2(l//)-thione (III.92), and not the isomeric 4-methyl derivative as previously thought [32]. Methylation of (III.92) (Mel-KjCOj-DMF) followed by reduction (LiAlH4-Et20), methoxymethylation, and oxidation with w-chlorobenzoic acid led to the alcohol (III.98) (50%), the ether (Ill.lOO)... 

Chlorohenzoic acid [74-11-3] M 156.6, m 238-239°, pK 3.99. Purify it as for /w-chlorobenzoic acid, has also been crystallised from hot water, and from EtOH. [Beilstein 9 IV 973.]... 

In order to better understand the properties of the metathesized plant oils, postmodification of these polymerized seed oils was also examined [25]. To explore the possibilities of new materials that could arise from the polymerized oils, Larock and coworkers evaluated both the hydrogenation and epoxidation of metathesized soybean oils. Normally, thermally polymerized metathesized oils yield a yellow, brittle gel. This brittle gel is often undesirable, so other processes were investigated to develop a more usable material. In order to alter the properties of the material, complete hydrogenation was accomplished with 10% palladium on carbon to produce a white/pale cream-colored, crystalline material with melting points between 53 and 60 C. This metathesized soybean oil was also treated with conditions to invoke epoxidation of the double bonds. Unfortunately, the initial attempts with m-chloroperbenzoic acid (mCPBA) were problematic for the metathesized soybean oil despite being satisfactory for unaltered soybean oil. It was found that material that had been epoxidized by mCPBA would polymerize in a few hours, most likely due to the difficulty in the complete removal of the w-chlorobenzoic acid generated during the epoxidation. To circumvent this problem, conditions... 

Photolytic. Plimmer and Hummer (1969) studied the irradiation of chloramben in water (2-4 mg/L) under a 450-W mercury vapor lamp (7, >2,800 A) for 2-20 h. Chloride ion was released and a complex mixture of colored products was observed. It was postulated that amino free radicals reacted with each other via polymerization and oxidation processes. The experiment was repeated except the solution contained sodium bisulfite as an inhibitor under a nitrogen atmosphere. Oxidation did not occur and loss of the 2-chloro substituent gave 3-amino-5-chlorobenzoic acid (Plimmer and Hummer, 1969). 

Crosby, D.G. and Leitis, E. Photodecomposition of chlorobenzoic acids, /. Agric. Food Chem., 17(5) 1033-1035, 1969. Crosby, D.G. and Moilanen, K.W. Vapor-phase photodecomposition of aldrin and dieldrin. Arch. Environ. Contam. Toxicol, 2(l) 62-74, 1974. 

A series of oxovanadium(iv) carboxylates V0(RC02)2 (RCO2 = acetate, propionate, butyrate, isobutyrate, valerate, pivalate, phenylacetate, benzoate, or w-chlorobenzoate) have been prepared by the reaction of freshly prepared hydrated V2O4 with a mixture of the corresponding acid and anhydride in toluene or DMF solution, and/or by the reaction of VOCI2 and the corresponding carboxylic acid in aqueous solution. I.r., electronic, and e.s.r. spectra... 

Layton, A. C., Sanseverion, J., Wallace, W., Corcoran, C. Sayler, G. S. (1992). Evidence for 4-chlorobenzoic acid dehalogenation mediated by plasmids related to pSS50. Applied and Environmental Microbiology, 58, 399-402. 

Dinitro-2-chlorobenzoic Acid, col ndls(from w), mp 196-200°, bp 24 0-41°, dec ca 25 3°, explodes on heating to higher temp other props methods of prepn are given in Beil(Ref 1) and... 

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%). 

Oxidation of similarly substituted 3,6-dihydro-27/-selenines 91 with w-chloroperoxybenzoic acid affords the corresponding selenopyrans 92 as well as its 3-chlorobenzoic acid addition product (Equation 38) <1993CC577>. This reaction and that mentioned in Scheme 4 presumably proceed through initial oxidation at selenium followed by a Pummerer-type a-oxidation. Typical yields of the selenopyrans were relatively modest. The effect of base on this reaction was investigated however, it was not clear whether added base was really helpful in improving yields in the reaction. 

Treatment of the isomeric dihydroselenines 93 containing electron-withdrawing groups in both the 2- and 6-positions with w-chloroperbenzoic acid also leads to formation of Pummerer-type oxidation products, the 4H-selenines 94 and the corresponding w-chlorobenzoate ester by-products (Equation 39) <1999J(P1)1155>. The esters could be converted to the corresponding 477-selenines by treatment with polyphosphoric acid trimethylsilyl ester (PPSE), a useful reagent for eliminations under neutral conditions. These 4/7-selenines were key intermediates in the synthesis of selenabenzenes. 

Details of the preparation of p-chlorotoluene are given in Expt 6.71, which also includes o-chlorotoluene, chlorobenzene, w-chloronitrobenzene and o-chlorobenzoic acid as examples of cognate preparations. 

In the following epoxidation step, m /a-chlorobenzoic acid (w-CPBA) has the choice to attack the 10,11-double bond or the 13,14-double bond. Because a hydrogen bond between the alcohol at C-9 and the peracid stabilizes the transition state 80, only the 10,11-double bond is epoxidized. In addition, this hydrogen bond also directs the attack to come from the same side as the alcohol and thus leads to a high substrate-controlled stereoselectivity. 

The recovery of the wi-chlorobenzoic acid, the by-product from w-chloroperbonzoicacid oxidations, i.s facilitated by using midhyh ue chloride as the solvent in peroxidations since the p( ra.cid is very soluble whereas the acid is (jiiite insoluble. ... 

Cool the solution of n-butyl-lithium to — 35° in a Dry Ice - acetone bath and add, whilst stirring vigorously, a solution of 48 g. of w-chlorobromo-benzene (Section IV,62) in 75 ml. of anhydrous ether. Stir for 8-10 minutes and pour the mixture with stirring on to a large excess of solid carbon dioxide in the form of a Dry Ice - ether slush contained in a -litre beaker. Isolate the acid as detailed above for p-Toluic acid and recrystallise it from hot water. The yield of m-chlorobenzoic acid, m.p. 150-151°, is 27 g. 

Synasia Fine Chem. http //www.synasia.com] TCI Am. http //www.tciamerica.com p-Chlorobenzoic acid CAS 74-11-3 EINECS/ELINCS 200-805-9 Synonyms Benzoic acid, 4-chloro- Benzoic acid, p-chloro- p-Carboxychlorobenzene Chloradracylic p-Chlorbenzoic acid 4-Chlorobenzoic acid Chlorodracylic acid Empirical C7H5CIO2 Formula CIC6H4COOH Properties Wh. to off-wh. light fluffy powd. or triclinic cryst. sol. in DMSO, 95% ethanol, methanol, acetone si. sol. in ether sol. < 1 mg/ml in water insol. in CS2, CCU, ligroin, benzene m.w. 156.57 sp.gr. 1.541 (24/4 C) m.p. 239-243 C b.p. subl. 

FIG. 4 Plots of vapor pressure of the crystalline substances versus the time required to become amorphous in mixtures with activated carbon. (O) At 25°C and atmospheric pressure ( ), at 40°C and reduced pressure. 1, Benzoic acid 2, o-hydroxybenzoic acid 3, w-hydroxybenzoic acid 4. p-hydroxybenzoic acid 5, o-chlorobenzoic acid 6, m-chlorobenzoic acid 7, p-chlorobenzoic acid. (From Ref. 13.)... 

---