Carboxylic function, introduction

The use of carbonate precursor (56) allows the introduction of a carboxylic function in the cycloadduct. The proposed mechanism involves internal delivery of a Pd-bound carbon dioxide to the TMM unit as depicted in Scheme 2.17 [27, 28]. 

We have developed an efficient and practical method for clean oxidation of starch (21-23) resulting in the oxidation of primary alcohol function in Ce position and the cleavage of vicinal diols in C2 and C3 position (Figure 30.2). We used small amounts of cheap iron tetrasulfophthalocyanine catalyst, pure water as reaction medium and H2O2 as clean oxidant to achieve a one-pot conversion of starch resulting in the introduction of aldehyde and carboxyl functions in polymer chains. The iron content... 

As example of introduction of amino and a carboxylic functions in a rigid bicyclic glyco-structure, compound 14-S was treated with tetrabutylammonium azide in toluene at 70 °C, affording the azide 30-S in 87 % yield (Scheme 9). 

The oxidative introduction of carboxylic functions to nanotubes provides a large number of CNT-functional exploitations and permits covalent functionalization by the formation of amide and ester linkages and other carboxyl derivatives [24]. Bifunctional molecules (diamines, diols, etc.) are often utilized as linkers. More illustrative examples are nanotubes decorated with amino-functionalized dendrimers, nucleic acids, enzymes, etc., and the formation of bioconjugates of CNTs [96]. 

The present method consists of three steps as illustrated in Scheme 1. In the first step, monolayer films of polyamic acid long chain alkyl-amine salts 4 at the air-water interface are prepared.(9) Unexpectedly, the polyamic acid 3 itself, which possess hydrophilic carboxyl functions in the polymer backbone, did not afford a stable monolayer at the air-water interface. Introduction of a hydrophobic long alkyl chain into 3 was performed by mixing polyamic acids and longchain alkylamines. Polyamic acid salts 4, thus obtained, afforded very stable monolayer films at the air-water interface. In the second step,(10) the polyamic acid salt monolayer films are successfully deposited on appropriate plates such as glass, quartz, or silicon wafer. Finally polyimide multilayer films are obtained by treatment of polyamic acid salt multilayer films on the plates with a mixture of acetic anhydride and pyridine. 

Carboxylation reactions based on carbon dioxide have a great interest as the direct introduction of the carboxylic functionality represents, wth respect to the conventional synthetic methodologies, a way for both saving energy and reducing the production of wastes. Despite such aspects, that have a positive environmental impact, the only "direct carboxylation" process exploited at the industrial level is the more-than-one-hundred-years old Kolbe-Schmitt reaction. This process converts phenol (in the form of a Group 1 element salt) and carbon dioxide into a mixture of o- and p-OH-benzoic acid. The major product depends on the reaction conditions and the metal used (Na or K, respectively). This reaction has been recently reviewed [4] by several research groups and extended to other substrates. 

Functionalization Introduction or modification of functional groups Chlorination/bromination of polyolefins capping carboxylic groups on polyesters ... 

Flemion is quite different from prior membranes in that it is based on specific perfluorinated copolymers with pendant carboxylic acid as a functional group. The introduction of carboxylic functions in the polymer has realized high permselectivity in cation transport with high conductivity, which is indispensable to electrochemical application of ion exchange membranes. 

The polymeric complexes derived from 4-nitro- and cyanostilbazoles also show a smectic A phase up to about 200 °C [78a]. Polysiloxane complexes 32 also exhibit thermally stable smectic A or C mesophases [79-81]. These carboxyl-functionalized polymers and stilbazoles are miscible in a whole range of composition and show stable mesomorphic behavior [26, 79]. The introduction of the chiral stilbazole for the formation of a mesogenic complex leads to the induction of ferroelectricity [80]. Polymeric complex 33 exhibits a chiral smectic C phase, while no ferroelectricity is observed for each of single components. The value of spontaneous polarization for 33 x — 0.43, n = 5) is 21.0 nC/cm at 112 °C. The hydrogen bonding between the carboxylic acid and... 

Mycobactin species produce a range of siderophores, the water-soluble exochelins (for instance, exochelin MS 11), mycobactin P 1 (a hydrophobic siderophore, which is not secreted from the organism), and the carboxymy-cobactins (which are also secreted) (Table 5). The car-boxymycobactins are similar to mycobactin P, the only difference being the introduction of a co-carboxyl function on the central lipid substituent. It is proposed that the exochelins and carboxymycobactins scavenge iron from the environment and donate it to mycobactin P. which acts as an intracellular ion store. ... 

A decrease in toughness above an optimum value of the functionality of the liquid rubber can be explained in terms of solubility parameter and chemical interactions. The solubility parameter of epoxy is higher than acrylate rubber (PEHA). With the introduction of carboxyl functionality the solubility parameter of the acrylate oligomer increases. When the functionality reaches an optimum value, the solubility parameter difference between the epoxy and acrylate rubber becomes less than 0.1. As... 

Oxidation is an important tool for the introduction of carbonyl and carboxyl fiinctions into biopolymers. The tendency of the oxidation of polysaccharides depends substantially on the nature of the oxidants and the conditions. Most of the oxidants known from the low-molecular organic chemistry produce both carbonyl and carboxyl functions to a varying extent depending on the... 

During the course of a peptide synthesis, protection of the amino and carboxyl functions may not be adequate. Under the conditions of peptide bond formation nucleophilic or other chemically reactive amino acid side chains may participate in unwanted side reactions. This may be avoided by protection of these side chains with protecting groups that meet the same general requirements of all protecting groups introduction and removal under mild conditions, etc. 

The following sections describe the applications of substituted 1,1-diphenylethylene chemistry for the preparation of phenol, amino, and carboxyl functionalized polymers as well as for the preparation of polymers with aromatic functional groups which provide fluorescent labels. These examples show that anionic functionalization chemistry utilizing substituted 1,1-diphenylethy-lenes as outlined herein provides a versatile and general functionalization methodology for quantitative introduction of functional groups at the chain ends and within the polymer chain by design. 

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