Alkoxylation-carboxylation reactions

Pyridinecarboxylates (99) give photosubstitution products on irradiation with alcohols the products have alkyl or alkoxy substituents, and the product ratios depend on the absence or presence of added mineral acid. A mechanistic rationalization is presented, based on the involvement of a triplet excited state located largely on C==0 or a triplet located largely on the ring (for alkylation), and a singlet excited state (for alkoxylation). The reaction of pyridinecarboxylic acids in the presence of transition-metal ions is reported pyridine-2-carboxylic acid gives pyridine and 2,2 -bipyridyl with iron(iii), but 2-pyridone with copper(ii) pyridine-3-carboxylic acid (100) with Fe gives a dehydrodimer without decarboxylation. 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

Other functional groups which have a heteroatom rather than a hydroxyl group capable of directing the hydrogenation include alkoxyl, alkoxycarbonyl, carboxylate, amide, carbamate, and sulfoxide. The alkoxy unit efficiently coordinates to cationic iridium or rhodium complexes, and high diastereoselectivity is induced in the reactions of cyclic substrates (Table 21.3, entries 11-13) [25, 28]. An acetal affords much lower selectivity than the corresponding unsaturated ketone (Table 21.3, entries 14 and 15) [25]. 

No analogous reactions take place with carboxylic acid esters. Cristol and his co-workers [49] therefore suggest that initially an alkoxyl ion is formed and afterwards the corresponding alcohol and nitrate ion are produced ... 

A survey of the chlotomethylation of aromatic compounds has been made, and a thorough study of the conditions of the reaction for the production of benzyl chloride has been carried out. The reaction is generally applicable to aromatic hydrocarbons. The effect of substituents on the ease of chloromethylation is pronounced alkyl and alkoxyl groups facilitate the introduction of the chloromethyl group, whereas halogen, Carboxyl, and nitro substituents retard or prevent the reaction. Zinc chloride, sulfuric acid, and phosphoric acid have been used as catalysts when needed. A chief by-product is the f is -chloromethyl compound. 

Benzoic acids substituted with alkyl, halo, hydroxyl, alkoxyl, cyano, or nitro groups react to give the corresponding substituted anilines in 41-80% yields. The carboxyl group in an a-amino acid does not react with hydrazoic acid the reaction proceeds, however, if the amino group is further removed. This difference in reactivity is shown by the conversion of a-aminoadipic acid to i(-ornithlne (75%). ... 

The two-electron process in the electrodecarboxylation of carboxylates has been intensively investigated from the mechanistic and synthetic viewpoints. Significant progress of such carbenium reactions has been recognized in alkoxylation, acetoxylation, acetamida-tion, olefin formation ( 6-elimination), rearrangement, C-C bond cleavage, and so on. Typical reaction patterns of the electrogenerated cation intermediates and their synthetic potentialities are discussed next. 

The introduction of a hydroxyl group at the -carbon atom both increases the reactivity of the molecule and results in the appearance of radicals formed by abstraction from the a-position (e.g. CHg.C(OH). CO2H from lactic acid). These observations, and those described earlier for the reactions of alcohols, ethers, and ketones, are correlated by the assumption that the hydroxyl radical is markedly electrophilic the carbonyl and carboxylic groups deactivate the C—H bonds in their vicinity, reaction tending to occur predominantly at more distant sites, whereas the hydroxyl and alkoxyl groups, having available p electrons, activate the C—H bonds to which they are attached, as represented by the contribution of such structures as (38) and (39) to the transition state for the reaction ... 

The alkoxylation of these structures, having carboxyl groups and hydroxyl groups, is a self catalysis process, catalysed by the acidic -COOH groups. Two simultaneous reactions take place the esterification of carboxyl groups with PO (reaction 16.14) and the etherification of hydroxyl groups (reaction 16.15) [34]. 

Substitution of an amino for the alkoxyl group of simple aliphatic ethers has little preparative importance the ether linkage must be weakened by a carbonyl, carboxyl, or nitrile group in the -position if the reaction is to occur under not too drastic conditions. Certain /8-methoxy ketones of type (17) can be converted into / -amino ketones below 100°.1081 Cleavage of the ether group in activated enol ethers is still easier for instance, 2-(acetoxymethylene)-... 

Abstract Progress in the field of metal-catalyzed redox-neutral additions of oxygen nucleophiles (water, alcohols, carboxylic acids, and others) to alkenes, alkynes, and allenes between 2001 and 2009 is critically reviewed. Major advances in reaction chemistry include development of chiral Lewis acid catalyzed asymmetric oxa-Michael additions and Lewis-acid catalyzed hydro-alkoxylations of nonacti-vated olefins, as well as further development of Markovnikov-selective cationic gold complex-catalyzed additions of alcohols or water to alkynes and allenes. 

Transesterification. lAlkoxy-de-alkoxylation or Alcoholysis of carboxylic esters] It is catalyzed by acids or bases. It is an equilibrium reaction and should be shifted in the desired direction. 

Commercial poly(butadiene), which is mainly the 1,4 isomer, is also used to improve the impact resistance of polystyrene (Chapter 1). Polydienes also increase the rate of physical disintegration of polyblend containing them. The addition of a styrene-butadiene block copolymer e.g. SBS, page 9 et seq.) to polyethylene also accelerates the peroxidation of the latter. However, this system also requires a polymer-soluble transition metal ion catalyst e.g. an iron or manganese carboxylate) to increase the rate of photooxidation in the environment by the reactions shown in Scheme 5.3. The products formed by breakdown of alkoxyl radicals (PO ) (Scheme 3.4) are then rapidly biodegradable in compost (page 107 et seq.). 

Diene platinum complexes such as (COD)PtCl2, (NBD)PtCl2 (NBD = norbor-nadiene) and (DPD)PtCl2 (DPD = dicyclopentadiene) easily react with nucleophilic reagents such as carboxylates, alkoxylates, amines and hydroxides to afford the addition products in high yields [8,114- 117]. For example, reactions are shown in eqs. (21.41)-<21.43). 

Hydroperoxides decompose relatively slowly at ambient temperatures in the dark, but in light they are readily photolysed to free radicals, (Scheme 1.1, reaction d). Consequently, the rate of photo-oxidation of the hydrocarbon polymers is orders of magnitude higher than thermal oxidation. In addition, small amounts of transition metal compounds, notably iron, cobalt, manganese and copper, have a powerful catalytic effect on radical formation from hydroperoxides [14], leading to rapid molecular weight reduction by breakdown of the intermediate alkoxyl radical and the formation of carboxylic acids and esters as oxidation end products (see Scheme 1.2) [15]. 

Usually the above method may be applied to substances with a free phenolic hydroxyl group and a free para position or a para position that is substituted by a halogen, hydroxyl or alkoxyl, sulphonic acid or carboxylic acid group since in general these substances give a positive reaction. 

A few examples of polymerization reactions catalyzed by MOFs are reported [161]. Zn carboxylate [162] was shown to catalyze the polymerization of propylene with CO to polycarbonates (M = 75,000g/mol). Alkoxylation of propylene glycol or acrylic acid with ethylene/propylene oxide resulted in polyols. Radical polymerization of divinylbenzene was performed using [M Cbdcj CtedjJ (M=Cu, Zn) [163-165]. 

The palladium(II)-catalyzed olefin carbonylation reaction was first reported more than 30 years ago in studies by Stille and co-workers and James et al. The reaction of carbon monoxide with cis- and tra 5-but-2-ene in methanol in the presence of palladium(II)-chloride and copper(II)-chloride yielded threo- and eryt/zro-3-methoxy-2-methyl-butanoate, respectively. The transformation that was based on the well-known Wacker process for oxidation of ethylene into acetaldehyde in water " is now broadly defined as the Pd(II)-catalyzed oxycarbonylation of the unsaturated carbon-carbon bonds. This domino reaction includes oxypalladation of alkenes, migratory insertion of carbon monoxide, and alkoxylation. Since the development of this process, several transformations mediated by palladium(II) compounds have been described. The direct oxidative bisfunctionalization of alkenes represents a powerful transformation in the field of chemical synthesis. Palladium(II)-promoted carbonylation of alkenes in the presence of water/alcohol may lead to alkyl carboxylic acids (hydrocarboxylation), diesters [bis(aIkoxycarbonyla-tion)], (3-alkoxy carboxylic acids (alkoxy-carboxylation), or (3-alkoxy esters (alkoxy-carbonylation or alkoxy-alkoxy-carbonylation). Particularly attractive features of these multitransformation processes include the following ... 

As shown in Table 26.2, the general formula of an ester is RCCXTR. Comparing the general formula of an ester with that of a carboxylic acid, we see that an ester is a molecule in which the hydroxyl group (—OH) of a carboxylic acid functional group is replaced by an alkoxyl group (—OR ). In the lab, esters can be prepared by the reaction of a carboxylic acid and an alcohol. The products of the reaction are an ester and a water molecule. 

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