Acid chlorides Subject

This corresponds to a yield of benzocyclobutenone, >99% homogeneous by VPC, of 32% with respect to the 2-toluic acid chloride subjected-to pyrolysis, and of 63% with respect to the 2-toluic acid chloride consumed in the reaction. 

Because of the presence of an extended polyene chain, the chemical and physical properties of the retinoids and carotenoids are dominated by this feature. Vitamin A and related substances are yellow compounds which are unstable in the presence of oxygen and light. This decay can be accelerated by heat and trace metals. Retinol is stable to base but is subject to acid-cataly2ed dehydration in the presence of dilute acids to yield anhydrovitamin A [1224-18-8] (16). Retro-vitamin A [16729-22-9] (17) is obtained by treatment of retinol in the presence of concentrated hydrobromic acid. In the case of retinoic acid and retinal, reisomerization is possible after conversion to appropriate derivatives such as the acid chloride or the hydroquinone adduct. Table 1 Hsts the physical properties of -carotene [7235-40-7] and vitamin A. 

The esters are prepared by first treating estradiol with the appropriate acid chloride. The resulting diester, 27, is then subjected to mild acid or basic hydrolysis in this way, the phenolic ester group is removed selectively. 

After further working up there is obtained an oily crystalline residue which is subjected to chromatography on silica gel. The 16a-methyl-6a,9a-difluoro-A -pregnadien-11/3,21-diol-3,20-dione is eluated with ethyl acetatereacted with valeric acid chloride to give the valerate ester. 

In addition to those methods already discussed, ketones can also be prepared from certain carboxylic acid derivatives, just as aldehydes can. Among the most useful reactions of this type is that between an acid chloride and a Gilman diorganocopper reagent such as we saw in Section 10.8. We ll discuss this subject in more detail in Section 21.4. 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

Nitriles can also be obtained by the method of Kolbe alkyl iodides (bromides or chlorides) are heated with alkali cyanide (example, benzyl cyanide), or salts of alkylsulphuric acids are subjected to dry distillation with potassium cyanide ... 

Several papers have been devoted to the subject of reactions of phosphoranes with carboxylic acids and their derivatives. Thus triphenylphosphine dibromide (111) in acetonitrile cleaves lactones,93 while the corresponding dichloride (112) converts esters into acid chlorides.94 The reactions of esters with phosphorus pentachloride (101) have been studied further,95 and the influence of structural changes on the yields of products (113) and (114) has resulted in minor modifications to the mechanism previously96 outlined. 

Photolytic. Dalapon (free acid) is subject to photodegradation. When an aqueous solution (0.25 M) was irradiated with UV light at 253.7 nm at 49 °C, 70% degraded in 7 h. Pyruvic acid is formed which is subsequently decarboxylated to acetaldehyde, carbon dioxide, and small quantities of 1,1-dichloroethane (2-4%) and a water-insoluble polymer (Kenaga, 1974). The photolysis of an aqueous solution of dalapon (free acid) by UV light (X = 2537 A) yielded chloride ions, carbon dioxide, carbon monoxide, and methyl chloride at quantum yields of 0.29, 0.10, 0.02, and 0.02, respectively (Baxter and Johnston, 1968). 

The acetone extracts were diluted 2 1 with water and partitioned against methylene chloride. The methylene chloride-soluble extracts were analyzed by comparative TLC (X). The aqueous phases were concentrated to dryness and dissolved in water that contained 5% acetonitrile and 0.2> acetic acid. These solutions were applied to SEP-PAK cartridges (Waters Associates) and the cartridges were washed with 5-10 ml of water and eluted with 5 ml of 50t acetonitrile. From 90 to 95% of the 1 C was recovered from the cartridges in the 50% acetonitrile eluate. The eluates were concentrated to dryness and dissolved in 18% acetonitrile/1% acetic acid and subjected to HPLC as previously described for PCNB metabolism in peanut roots (6). 

A mild method for generating reactive ketenes has been developed59 which involves the dehalogenation of cc-bromo carboxylic acid chlorides at low temperatures (— 80 C) with pentacarbonylmanganese(IV) anion [Mn(CO),]. For example, subjecting 16 to these conditions provides a practical synthesis of the corresponding eyclobutanediones 18. 

Can be prepd by treating the appropriate acid chloride or anhydride with Na or H peroxide in the presence of a base (Ref 4) Alperox C is stable at ord temp, but because of its rather low mp, it should be stored in a cool place prolonged storage at temps close to or above its nip causes decompn It burns upon ignition but without violent-decompn characteristic of most organic peroxides should not be subjected to friction, such as by grinding... 

A mixture of acid chloride (20 mmol), spray-dried KF (2.32 g, 40 mmol) and anhyd MeCN (20 mL) was stirred for 3 h at rt. Inorganic material was removed by filtration and the filtrate was poured into an aqueous solution of HC1. The oily material was separated and subjected to distillation. 

Fluorinated diaeyl peroxides have acquired an important role in organo-fluorine chemistry and have become the subject of intensive research.202-204 Bis(per)fluoroaIkanoyI or -aroyl peroxides are generally synthesized in excellent to moderate yields in the same manner as for nonfluorinated peroxides, that is by reaction of acid chlorides or anhydrides with sodium peroxide or hydrogen peroxide.205-206 Similarly, perfluoroalkanoyl chlorides and fluorides, many of which are accessible by industrial processes, react with hydrogen peroxide in the presence of hydroxide to give the diacyl peroxides l.206-207... 

The alcohol 177 was converted to starting substrates oxazolidinone 178 by acylation followed by reduction of the azide function along with cyclization. Oxazolidinone 178 was protected with f-butylpyrocarbonate-4-(dimethylamino) pyridine (DMAP) and triethylamine, which was further subjected to reductive cleavage of the benzyl ester unit to afford carboxylic acid 179. The treatment of 179 with solution of l-chloro-/V./V,2-trimethyl-1-propenv I airline resulted in the easy formation of the corresponding acid chloride which on reaction with imine in the presence of triethylamine provided the stereoselective formation of spiro-p-lactam 180. 

The various methods for introducing a formyl group (—COH) into a phenolic nucleus are discussed in Section 6.10.1, p. 990. The formation of phenolic ketones (e.g. HO-C6H4-COR) by the standard Friedel-Crafts acylation procedure (i.e. the reaction of a phenol with an acid chloride in the presence of aluminium chloride) does not always give acceptable yields except in the case of polyhydroxyphenols (p. 1006). The preferred method is to convert the phenol into the phenyl ester and to subject this to rearrangement (the Fries reaction) in the presence of aluminium chloride. 

To a stirred solution of [4-(2-pyrimidinyl)piperazino]ethylamine (2.0 g, 0.01 mol) in 50 ml of methylene chloride, adamantane-l-carboxylic acid chloride (3.6 g, 0.018 mol) and triethylamine (2.9 g, 0.015 mol) were added. Stirring was continued at room temperature overnight. The methylene chloride solution was washed with water, dried over anhydrous sodium sulfate and evaporated under reduced pressure. The remaining residue was subjected to preparative HPLC. The residue was dissolved in ethyl acetate (10 ml) and subjected to flash chromatography using a 9 inch column of silica gel and ethyl acetate as the eluent. The N-[2-[4-(2-pyrimidinyl)-l-piperazinyl]ethyl]tricyclo[3.3.1.1(3,7)] decane-l-carboxamide was separated. 

The reaction of carbonyl compounds with P(III) acid chlorides has been widely discussed in the literature. The most complete information on this subject was compiled in the review [42]. As far as the carbonyl derivatives of indole in such reactions are concerned the information here is sparse. 

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