Metal alkanoates

ILCs where the mesomorphic properties of the phases are dictated by the structure of an organic anion are rare. A sulfonate group attached to a cholesteryl unit was synthesized and exhibited a smectic phase [34], An SmA phase was also observed in pyridinium salts of the [closo-lCB H, ] anion [18], Metal alkanoates will be discussed in the next section. 

On the basis of small angle X-ray scattering, it was shown that the metal alkanoate matrix in the mesophase consists of bilayers. In thermotropic ionic liquid aystals, an alternation exists of hydrophobic alkyl chains and conductive layers which contain metal cations and anionic carboxylic groups. In lyotropic ionic liquid aystals, there are metal cations, carboxylic groups, and water between the hydrophobic alkyl chains layers. As a result, metal alkanoates form an SmA structure [64]. 

These materials are extranely attractive for their optical and electrical properties. They have a high intrinsic ionic conductivity, which varies exponentially with temperature and is also anisotropic due to their bi-layer spatial structure [64]. For example, the lyotropic metal alkanoate potassium caproate showed a higher electrical conductivity in the smectic phase than in isotropic solutions. Since they are much less solvated within the layered structure of the smectic phase than in dilute... 

Klimiisheva GV, Garbovsldi Y, Bugaichuk S et al (2009) Novel nanocomposite materials based on mesomorphic glasses of metal alkanoates structure and nonUnear optical properties. High Eneig Chem 43 532-535... 

Bugaychuk S, Klimusheva G, Garbovskiy Y et al (2006) Nonlinear optical properties of composites based on conductive metal-alkanoate liquid crystals. Opto-Electron Rev 14 275-279... 

From a study of the decompositions of several rhodium(II) carboxylates, Kitchen and Bear [1111] conclude that in alkanoates (e.g. acetates) the a-carbon—H bond is weakest and that, on reaction, this proton is transferred to an oxygen atom of another carboxylate group. Reduction of the metal ion is followed by decomposition of the a-lactone to CO and an aldehyde which, in turn, can further reduce metal ions and also protonate two carboxyl groups. Thus reaction yields the metal and an acid as products. In aromatic carboxylates (e.g. benzoates), the bond between the carboxyl group and the aromatic ring is the weakest. The phenyl radical formed on rupture of this linkage is capable of proton abstraction from water so that no acid product is given and the solid product is an oxide. 

The method described here belongs to a group of recently developed procedures comprising the spontaneous intramolecular acylation of active derivatives of metalated p-hydroxy alkanoates. These compounds are available by reactions of carbonyl compounds with ester enolates prepared from S-phenyl alkanethioates6 or phenyl alkanoates,15 as well as by Reformatsky16 or Darzens17 reactions of carbonyl compounds with phenyl a-halo alkanoates. 

Enantiocontrolled anti-selective Michael additions of the metalated ylides derived from a-(alkylideneamino)alkanoates are attractive as a new synthetic route to enantiomers of a-amino esters. Although there are a variety of chiral glycine equivalents available, only the enolates derived from 1,4-dihydropyrazine have been successfully applied to asymmetric Michael additions (Scheme 11.22) (103-105). In these reactions, the diastereoselectivities are high. 

Either enantiomer of a-alkylated alkanoic acids, 3-substituted dihydro-2(3//)-furanones and 3-substituted tetrahydro-2//-pyran-2-ones with known absolute configuration and high optical purities can be obtained from metalation and alkylation of chiral 4,5-dihydrooxazoles (see Section 1.1.1.4.3.). 

However some of N-hydroxylamino-alkanoic acids form nitroso compounds and some of the metal salts of such compounds are explosive as shown below ... 

Apart from C02 and metal carbonates, the most abundant carbonyl compounds of natural origin are carboxylic esters and amides. These occur as fats and lipids, which are esters of long-chain alkanoic acids (pp. 789-791), and as proteins, which are polyamides of natural amino acids. The same struc-... 

Highly stereoselective aldol reactions of lithium ester enolates (LiCR1 R2CC>2R3) with (/0-2-(/ -tolylsulfiny I (cyclohexanone have been attributed to intermediacy of tricoordinate lithium species which involve the enolate and the sulfinyl and carbonyl oxygens of the substrates.43 The O-metallated /<-hydroxyalkanoatcs formed by aldol-type reaction of carbonyl compounds with enolates derived from esters of alkanoic acids undergo spontaneous intramolecular cyclization to /1-lactones if phenyl rather than alkyl esters are used the reaction has also been found to occur with other activated derivatives of carboxylic acids.44... 

Scrimin and co-workers have extensively studied the ester-cleavage abilities of various Cu(II)-chelating bidentate ligand [(2-hydroxymethyl)pyridine] amphi-phile, 9, and related bolaphile, 10, in micellar media [32], The corresponding metallomicelles are powerful catalysts for the cleavage of substrates, e.g. p-nitrophenyl alkanoates, that do not coordinate with the metal-complex core. Subsequent studies demonstrated that tridentate ligand amphiphiles such as 9,... 

In this type of separation the analyte cations compete with the eluent cation for ion-exchange sites and move down the eolumn at different rates. The ionic eluent selected depends on the cations to be separated, the type of separation column and on the detector. In many cases an aqueous solution of a strong acid such as hydrochloric, sulfuric or methanesulfonic acid is a satisfactory eluent. Sample cations commonly separated include the following alkali metal ions (Li, Na+, K", Rb, Cs ), ammonium, magnesium, alkaline earths (Ca, Sr +, Ba ), and various organic amine and alkano-lamine cations. Most other metal cations are separated with a weakly complexing eluent. 

The simplest complexes exhibiting columnar mesophases are the dinuclear metal carboxylates [M2(02CR)4], derived from simple alkanoic acids which have been synthesized with a range of metals [156]. Early work concentrated upon copper(II) carboxylates, with X-ray studies confirming the phases as hexagonal columnar... 

Conjugated esters. Active Mn is prepared from MnCl2 via Li2MnCl4 and treating the latter with Li and 2-phenylpyridine. The active metal promotes reaction of 2,2-dichloro-alkanoic esters with aldehydes to furnish conjugated esters. ... 

The Claisen condensation is little used for the preparation of <%,/ -unsaturated carboxylic acids since the methods given above are usually preferable. Cinnamic esters have, however, been obtained by Claisen s method from aromatic aldehydes, alkanoic esters, and metallic sodium, e.g., methyl 4-methoxycinna-mate924 and ethyl 5-(2-furyl)-2,4-pentadienoate925 in yields between 70% and 80%. -Substituted cinnamic esters can also be obtained by this method, from higher alkanoic esters.926... 

Long-chain alkanoic acids have a limited use as surfactants. They are very weak acids having a pH range between 5 and 6. They are soluble in most organic solvents but purely soluble in water. Alkali metals and short-chain amines as counterions yield water-soluble soaps which, as a result of hydrolysis, form with free acids the dispersible 1 1 or 1 2 association complexes, so-called "acid soaps". 

Metalation of chiral oxazolines, derived from (15,25)-l-phenyl-2-amino-1,3-propanediol, followed by alkylation and hydrolysis, leads to optically active dialkylacetic acids, e.g. eq 22, 2-substituted butyrolactones and valerolactones, p-hydroxy and -methoxy acids, 2-hydroxy carboxylic acids, and 3-substituted alkanoic acids (eq 23). ... 

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