Acetic acid chloro-substituted

Benzofurazan (benz-1,2,5-oxadiazole) reacted with bromine by addition to give a4,5,6,7-tetrabromo adduct. Bromine in hydrobromic acid solution 4-brominated both 5-methyl- and 5-bromo-benzofurazans (74JHC8I3). When 4,7-dinitrobenzofurazan was treated with ammonium chloride in refluxing acetic acid, nucleophilic displacement gave rise to the 4-chloro-7-nitro derivative (83URP1004375). Naphtho[l, 2-c]furazans (42) are mainly 4-halogenated, but there is minor substitution in the 8-position (73CHE1331). 

The earliest oxidations were effected with nitrous fumes and later with mercuric oxide and isoamyl nitrite.74 Lead tetraacetate in acetic acid is in many cases the reagent of choice, but the removal of by-products can present some difficulties.75 IV-Haloimides and amides in alcoholic solutions have been reported to yield essentially pure tetrazolium salts76 and have been found specially useful in the preparation of heteroaryl-substituted tetrazolium salt.77,78 The novel formazans 49 have been successfully oxidized to 50 using 7V-chloro succinimide (Eq. II).79 tert-Butyl hypo-... 

PMR) trends that correspond to relative rates.179 From an examination of the displacement of chloride from l-chloro-5-nitrofuran by potassium iodide in acetic acid or by sodium sulfide in water it was concluded that the substitution need not be a true nucleophilic substitution. Initially there could be a transfer of one electron from the nucleophile to the furan nucleus the resultant radical anion loses chloride to form a furyl radical and product.179... 

Another of the important concepts in dealing with acid strength is illustrated by the dissociation constants for the chloro-substituted acetic acids. The dissociation constants are as follows CH3COOH,... 

Halogenation can be run under milder conditions using more active quaternary ammonium polyhalides such as pyridinium tribromide. The reaction between thiophene and benzyltrimethylammonium tribromide in acetic acid-ZnCl2 provided 2,5-dibromothiophene [6]. Chloro- and iodo-substituted thiophene derivatives may be prepared in the same manner. In comparison, bromination of thiophene employing 2 equivalents of NBS in chloroform gave 2,5-dibromothiophene in 56% yield [7]. 

Another growing technique is super-critical fluid chromatography. Recent references to soil analysis include the following applications aliphatic hydrocarbons, polyaromatic hydrocarbons, polychlorobiphenyls, dioxins, alkyl and aryl phosphates, chloro, organophosphorus, triazine, substituted urea, phenoxy acetic acid, Dacthal herbicides and insecticides and mixtures of herbicides and pesticides and mixtures of organic compounds. 

Sprio et al. reported the preparation of 6-acetylimidazo[2,l-Z)]thiazoles derivatives 57 (74JHC91). TTie synthesis involves substituted 4-(2-thiazo-lyl)aminoisoxazoles 56, which were obtained in good yield by the reaction of N-(3,5-dimethylisoxazol-4-yl) thiourea 55 with a-chloro ketones. Subsequent isoxazole ring opening led to intermediates which readily underwent cyclization by refluxing in acetic acid or ethanol/hydrochloric acid. 

With one equivalent of IV-chlorosuccinimide (NCS) in acetic acid at 25°, thienothiophene 1 gives the initial thienothiophene 1 (11%), 2-chloro- (78%) and 2,5-dichlorothieno[2,3-6]thiophene (10%), while a 70% yield of 2,5-dichlorothieno[2,3-6]thi(q)hene is produced with two equivdents of NCS. Similar results were obtained from thienothiophene 2 with one and two equivalents of NCS. About 0.4% 3-chlorothieno[2,3-6]thiophene was detected by gas-liquid chromatography among the chlorination products of 1. The same amount of /9-isomer is found in thiophene chlorination products. In the case of thienothiophene 2, the corresponding /9-isomer was not observed in the reaction products. To identify 3-chloro-substituted thiophene and thienothiophenes 1 and 2 in reaction mixtures, these compounds were prepared independently from the corresponding 3-bromo derivatives by Uthiation followed by chlorination at —70°. 

H, R = Me R = R = H, R = Me R> = R = Me, R = H R = OH, R = R = 9-Benzyloxymethylcarbazole and its 3-chloro, 3,6-dichlo-ro, and 3-nitro analogs gave comparable products (120) but only under acid catalysis. However, the use of acid with 9-hydroxymethylcarbazoles led to 3-substitution and the formation of 121 (R = H, Cl, and 9,9 -Dicarbazolylmethane is formed from 9-hydroxymethylcarbazole on treatment with acetic acid or from its acetate on reaction with carbazol-9-ylmagnesium iodide. ... 

Reactions of a number of l-phenylimidazole-2-carboxamides with chlorine in acetic acid, NCS, or hypochlorite failed to introduce chlorine into the 4- or 5-positions (80JHC409). Chlorination of a variety of 2,4-disubstituted imidazoles, however, was quite facile, Thus, 2,4-diesters [83JCS(P1)809] and 2-amino-4-aryl compounds [80IJC(B)526] were readily 5-chlorinated, and even when both the 4- and the 5-positions were blocked, as in 5-aminoimidazole-4-carboxamide, 2-chlorination with iodine monochloride was possible (89MI5). When all three carbons were substituted (e.g., in 2,4,5-triphenyl-, 2-chloro-4,5-diphenyl-, and 2-trichloromethyl-... 

Ketene itself and simple alkylketenes are inert towards nonactivated alkenes. F or the preparation of cyclobutanones formally derived from ketene or an alkylketene and nonactivated alkenes, the more reactive dichloroketene or alkylchloroketenes can be used. The corresponding a,a-dichloro- or oc-chlorocyclobutanones can readily be dechlorinated by treatment with zinc in acetic acid, or tributyltin hydride in near quantitative yields. F or example cycloaddition of substituted cyclohexene to dichloroketene gave dichlorocyclobutanone 1 which was dechlorinated to 2 with zinc.13,18 Likewise cycloaddition of cycloalkcnes to chloro(methyl)ketene gave 3 which was dechlorinated to 4.14... 

Commerciol Dichlorohydrin consists of the above two isomers, the proportions of which depend on method of prepn d 1.36-1.39, bp 175-80°, flash p 74°, Glycerol was the main source for the prepn of glycerol chloro-hydrins until the process for direct substitutive chlorination of propylene to allyl chloride paved the way for synthesis by chlorohydrination of allyl chloride. In the synthesis from glycerol, excess HCI is used in the presence of 4% acetic acid. The reaction is run at 130° to yield 90% of product which is mainly the a,y-form. Synthesis from propylene yields a mixt of approx 70% a,/8-form 8c 30% a,y-form. Addn of HCI to epichlorohydrin, CH2 CHCH> Cl, at... 

Electrophilic chlorination of quinoline under neutral conditions occurs in the orientation order 3 > 6 > 8. Hammett ct+ values predict an order for electrophilic substitution of 5 > 8 = 6 > 3. The reactivity order can be affected by substitution of an electron-withdrawing group in the benzene ring, which directs the chlorination to the pyridine ring. Thus, NCS in acetic acid or sulfuryl chloride in o-dichlorobenzene converts 8-nitroquinoline into 3-chloro-8-nitroquinoline in high yield (91M935). 

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