Halides chloroformic acid ester

From Boron Halides. Using boron haUdes is not economically desirable because boron haUdes are made from boric acid. However, this method does provide a convenient laboratory synthesis of boric acid esters. The esterification of boron haUdes with alcohol is analogous to the classical conversion of carboxyUc acid haUdes to carboxyUc esters. Simple mixing of the reactants at room temperature or below ia a solvent such as methylene chloride, chloroform, pentane, etc, yields hydrogen haUde and the borate ia high yield. 

Phosgene, as well as the easier to handle diphosgene (chloroformic acid trichloromethyl ester) or triphosgene (carbonic acid bis(trichloromethyl) ester) transform primary, secondary and tertiary amides and thioamides to chloromethyleneiminium chlorides (25 equation 15), whereby the reaction with thioamides is of broader scope and proceeds with fewer side reactions. The amide chlorides derived from primary and secondary amides can lose HCl, giving nitriles or imidoyl halides, respectively. /V-Sub-stituted formamides can be converted to isonitriles via amide halides. ... 

Alkylmercaptomethyleneiminium salts (267 Scheme 39), which are accessible either by addition of thiols to the nitrile function in the presence of hydrogen halides or by reaction of chloroformic acid thioethyl ester with thioamides, can also be transformed to the corresponding thioimidates (268). 

The acylpalladium complex formed from acyl halides undergoes intramolecular alkene insertion. 2,5-Hexadienoyl chloride (894) is converted into phenol in its attempted Rosenmund reduction[759]. The reaction is explained by the oxidative addition, intramolecular alkene insertion to generate 895, and / -elimination. Chloroformate will be a useful compound for the preparation of a, /3-unsaturated esters if its oxidative addition and alkene insertion are possible. An intramolecular version is known, namely homoallylic chloroformates are converted into a-methylene-7-butyrolactones in moderate yields[760]. As another example, the homoallylic chloroformamide 896 is converted into the q-methylene- -butyrolactams 897 and 898[761]. An intermolecular version of alkene insertion into acyl chlorides is known only with bridgehead acid chlorides. Adamantanecarbonyl chloride (899) reacts with acrylonitrile to give the unsaturated ketone 900[762],... 

Other examples are acetoacetates alkylamines and alkylhalides/acid halides ethers esters chloroformates ketones lactames lactones malonates mercaptanes and orthoesters in aliphatics catechol/hydroquinone/resorcinol, cresidines haloaromatics in aromatics and coumarines, cyanuric chloride, picolines, quinolines, and thiazoles in heterocylics. 

Carboxylic acid chlorides and chloroformate esters add to tetrakis(triphenylphosphine)palladium(0) to form acylpalladium derivatives (equation 42).102 On heating, the acylpalladium complexes can lose carbon monoxide (reversibly). Attempts to employ acid halides in vinylic acylations, therefore, often result in obtaining decarbonylated products (see below). However, there are some exceptions. Acylation may occur when the alkenes are highly reactive and/or in cases where the acylpalladium complexes are resistant to decarbonylation and in situations where intramolecular reactions can form five-membered rings. 

The interaction of alkyl halides, preferably iodides or bromides, with hexamine in chloroform or alcohol solution forms quaternary ammonium salts which on heating with hydrochloric acid are readily converted to primary amines. The procedure has been employed successfully in the reaction of primary, but not secondary or tertiary, aliphatic halides, certain benzyl halides, halo ketones, halo acids, and halo esters. The yields range from 40% to 85%. 

Copper can be determined by use of ion associates, formed by the cationic complexes of Cu(I) with cuproine [63-65], neocuproine [65], bathocuproine [66] and thio-crown ethers [67,68], associated with the acid dyes such as Rose Bengal (e = 7.8-10 ) [63,65,66], the ethyl ester of eosin (e = 9.4-10 ) [64], and Erythrosin [63]. These ion-associates are extracted into chloroform [65,66], 1,2-dichloroethane [64,67,68], and other solvents. The ion-associates of cyanide [69] and chloride [70,71] complexes of Cu(I) with Methylene Blue (1,2-dichloroethane, = 9.8-10 ) [69], and Ethyl Violet (toluene, = 9.6-10 ) [70] are also worth mentioning. The halide complexes of Cu(I) with azo dyes have also been extracted. 

Carboxylic, and arylsulfonic acid halides react rapidly with pyridines generating 1-acyl- and 1-arylsulfonylpyridinium salts in solution, and in suitable cases some of these can even be isolated as crystalline solids. The solutions, generally in excess pyridine, are commonly used for the preparation of esters and sulfonates from alcohols and of amides and sulfonamides from amines. 4-Dimethylaminopyridine (DMAP) is widely used (in catalytic quantities) to activate anhydrides in a similar manner. The salt derived from DMAP and t-butyl chloroformate is stable even in aqueous solution at room temperature. " ... 

An alternative approach to increasing the rate of esterification is to activate further the intermediate (2). N-Bromosuccinimide has been used for this purpose, but unsaturation in the carboxylic acid or alcohol is not tolerated. More generally useful is the addition of an activated halide, usually A//y/ Bromide, to a chloroform solution of (1) and a carboxylic acid, resulting in formation of the acylimidazolium salt (3) (eq 4). Addition of the alcohol and stirring for 1-10 h at room temperature or at reflux affords good yields of ester in a one-pot procedure. These conditions work well for the formation of methyl, ethyl, and i-butyl esters of aliphatic, aromatic, and a,/3-unsaturated acids. Hindered esters such as i-butyl pivalate can be prepared cleanly (90% yield). The only limitation is that substrates must not contain functionality that can be alkylated by the excess of the reactive halide. 

Intramolecular acylations are quite common. The normal procedure involving an acid halide and Lewis acid can be used. One useful alternative is to dissolve the carboxylic acid in polyphosphoric acid (PPA) and heat to effect cyclization. This procedure probably involves formation of a mixed phosphoric-carboxylic anhydride. Cyclizations can also be carried out with an esterified oligomer of phosphoric acid called polyphosphate ester. This material is chloroform-soluble. ... 

The polyamide and the polyether segments are usually incompatible, phase separation often occurs and the reaction between the reactive chain-ends can only take place at the interface. This reaction can be accelerated by using very reactive functional groups, such as acid halides. The synthesis of polyamides and polyesters via interfacial polymerization has been extensively reviewed by P. W. Morgan [43] in the mid-sixties. A few years later, Castaldo et al. [44] successfully synthesized a poly(ether ester amide) based on PA6.6 and PEO. The a,oj-dihydroxy polyether was first reacted with a diacid chloride for several hours, either in the bulk or in chloroform, and at a rather low temperature (60-90°C). The mixture was then poured into a vigorously stirred aqueous solution of diamine and sodium hydroxide. Later, de Candia et al. [45] reproduced this technique to study the physical and mechanical properties of the copolymer. The same polymerization technique was also used to prepare copolymers based on PPO as the polyether segment and PA6.10 as the polyamide block [3,46,47]. 

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