Dimer acid, adducts

The extraction of most acids is accompanied by extraction of water. In the extraction of HNO3 by TBP into kerosene, many different species have been identified, several of which involve hydration. The ratio of acid adduct is not very predictable. For example, HCIO4 apparently is extracted into kerosene with 1-2 molecules of TBP, HCl into ethylether with one molecule of ethylether, etc. Also, the extracted acid may dimerize in the organic solvent, etc. Example 2 illustrates the complexity of the extraction of HNO3 by TBP into kerosene. 

The dimer [MCp 2CH3]2f f can also be viewed as a Lewis acid adduct. Monomer and dimer are in rapid equilibrium down to -60 C, giving rise to a single LU-CH3 resonance in the NMR spectrum of The limiting spectrum of A at -90 C shows a 1 1 2 pattern... 

ADDUCTS OF LIQUID EPOXY, CTBN AND DIMER ACID... 

Later, McPherson (39) demonstrated that the Inclusion of a CTBN/liquid epoxy adduct enhanced both the flexibility and adhesion of a dimer acid flexibllized epoxy/brominated epoxy mixture when cured with a combination of chlorendic and nadic-methyl anhydrides. With an epoxy-glass laminate as substrate, such mixtures were coated at 0.5-2.0 mils thickness, cured, sensitized and copper plated (1.5 mils) by an electroless process. 90 peel testing (2 inches/mln. rate, 25 C) gave 14.0 pli peel force where 5.0 pli is considered normal. 

Resin acid dimer adducts with maleic anhydride and acrylic acid were also used to prepare epoxy resins [107, 109]. The epoxy precursors were prepared by the reaction of the Diels-Alder adducts with di(ethanol)amine, followed by treatment with epychlorydrine under alkaline conditions, as shown in Fig. 4.21 for the acrylic acid adduct [109]. After curing, the ensuing materials produce high stability coats [109]. 

One vital observation made by Nierenstein was that there was a considerable reluctance of acyl bromides to form the corresponding bromomethyl ketones. Acid bromides on reaction with diazomethane were also found to form substituted 1,4-dioxanes or specifically 3,6-dibromo-3,6-diphenyl-1,4-dioxane 8, resulting from the dimerization of adducts. The dimerization according to him could be attributed to the poor mobility of the bromide compared to the chloride group. 

R = t-C Hg, L = THF [55]). Monomeric, solvent-free CP2MR have not been reported yet. From this it may be clear that the metals Sc and Y have strong tendency to fill their coordination sphere either by dimerization or adduct formation. Another indication of the strong Lewis acid character of Group IIIB complexes is the fact that compounds of the type Cp MCI can coordinate LiCl to give Cp2M(]i-Cl)2LiL2 (M = Sc, Y, La,... 

Addition compounds form with those organics that contain a donor atom, eg, ketonic oxygen, nitrogen, and sulfur. Thus, adducts form with amides, amines, and A/-heterocycles, as well as acid chlorides and ethers. Addition compounds also form with a number of inorganic compounds, eg, POCl (6,120). In many cases, the addition compounds are dimeric, eg, with ethyl acetate, in titanium tetrachloride-rich systems. By using ammonia, a series of amidodichlorides, Ti(NH2) Cl4, is formed (133). 

Currently, there is continuing work on an iadustry standard method for the direct determination of monomer, dimer, and trimer acids. Urea adduction (of the methyl esters) has been suggested as a means of determining monomer ia distilled dimer (74). The method is tedious and the nonadductiag branched-chain monomer is recovered with the polymeric fraction. A micro sublimation procedure was developed as an improvement on urea adduction for estimation of the polymer fraction. Incomplete removal of monomer esters or loss of dimer duriag distillation can lead to error (75). 

Evidendy, a dimerization of SeO takes place under the influence of the Lewis acid SbCls resulting in the centrosymmetric cydo-dodecasulfurdioxide adduct shown in Fig. 1. 

On reaction with Li-HMDS 492 and subsequent treatment with MegSiCl 14 a-ketoesters such as 512 afford N-silylated Schiff bases such as 513, which can be reduced to amino acids 514 or amino alcohols 515 and dimerized with methanol or H2O to give the imidazolone 516 [95]. Analogous treatment of benzil with Li-HMDS 492 and quenching with Me3SiCl 14 gives 517, which reacts with the Li-enolate of methyl isobutyrate 498 at 78 °C in THF to give the adduct 518 in 75%... 

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