Bruce W. Baldwin

Microwave oven synthesis of esters promoted by imidazole

Using imidazole as promotion agent, primary, secondary and phenolic alcohol compounds were esterified with aliphatic and aromatic carboxylic acid anhydrides. Heating a ternary mixture of alcohol, anhydride and imidazole in an unmodified microwave oven produced esters in low to high yields, depending on the steric bulk of the alcohol.

1H NMR study of chiral recognition of amines by chiral Kemp's acid diamide

Abstract Chiral recognition by homochiral Kemps acid diamide was studied by a 1 H NMR titration method. The diamide monoacid, prepared by amidation with enantiomerically pure ( S )-α-methylbenzylamine, gave a large chemical shift change for five amines studied and showed good enantioselectivity toward cis - N -benzyl-2-aminocyclohexanemethanol.

Improved microwave oven synthesis of amides and imides promoted by imidazole; convenient transport agent preparation

Microwave dielectric loss heating without solvent or support yields amides and imides from aromatic and sterically hindered acids in the presence of imidazole in good to excellent yields under mild irradiation conditions.

New Chiral Kemp's Acid Diamides for Chiral Amine Recognition by 1 H NMR

Two Kemps acid diamides were synthesized and applied to chiral amine recognition using 1H NMR analysis. One derivative based on 1-(1-naphthyl)ethylamine had good chiral recognition of six amines and was useful to determine the optical purity for three amines, i.e., methylbenzylamine, 1-(1-naphthyl)ethylamine and 1- henylpropylamine,however, the cyclohexylethylamine derivative showed little discrimination for the amines studied. Together with the results for alkylamines, it was shown that aromatic structure was important for aromatic shielding anisotropy and π––π interactions between host and guest. The structure of the 1-(1-naphthyl)ethylamine derivative in solution was also considered based on 1H NMR data and computer simulation.

Versatility of Kemp's acid imides as heavy metal ion carriers

Kemps acid imides transport transition-metal ions through a CHCl3 liquid membrane, most effectively transporting HgII with high selectivities (Hg/Ag = 5, Hg/Cu = 14, and Hg/Pd = 86 for an aromatic imide).

(1α,3α,5α)-1,3,5-Trimethyl-1,3,5-cyclohexanetricarboxylic Acid Acetonitrile Solvate

In the title compound, CHO.CHCN, both components have crystallographically imposed C symmetry. The hydrogen bonds between the three carboxylic acid groups of (1α,3α,5α)-1,3,5-trimethyl-1,3,5-cyclo-hexanetricarboxylic acid (Kemps triacid) and three other triacid moieties make a three-dimensional hydrogen-bonding network, producing large intermolecular cavities.

A metal-organic molecular box obtained from self-assembling around uranyl ions

We used the peculiar coordination geometry of uranyl ions to build a three-dimensional superstructure of inprecedented architecture. The complexation of uranyl ions by a monoester derivative of the cis,trans regioisomer of Kemp’s triacid and µ-peroxo bridges leads a cagelike molecule with a roughly parallelepipedic inner cavity of ca. 700 A3 able to host four medium-sized organic molecules.

Chromogenic reagent for mercury based on Kemp’s acid imide

Kemp’s acid imide type chromogenic reagent showed a significant colour change with excellent selectivity for Hg II over other transition- and heavy-metal ions.

A COMPUTATIONAL STUDY ON MAGNESIUM COMPLEXATION WITH FORMATE AND HYDROGEN MALONATE ANIONS

Abstract The complexation of magnesium with hydrogen malonate and formate anions was studied with ab initio calculations. At least HF/6-31G ∗ level of accuracy is necessary for a qualitatively correct description of the complexes. The coordination space of magnesium has to be filled to attain reliable results. If crystal structures are used as experimental references, at least part of the crystal interactions must be properly included in the calculations.

Conformation of cis,trans-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid derivatives: crystal structures and semiempirical molecular orbital calculations

The conformation of three derivatives of the cis,trans epimer of Kemp’s triacid with cis-carboxy groups, namely the 4-tert-butylbenzyl ester (1), the phenethyl ester (2) and the phenethyl amide (3) was investigated. The determination of crystal structures showed that, while 1 and 2 are in the boat conformation, previously unobserved in this family of compounds, 3 is in the chair conformation, all of them with axial carboxy groups. In the first two cases, dimers are formed by hydrogen bonding between carboxy groups of adjacent molecules whereas in the third case, the presence of other hydrogen bonds involving the amide groups gives rise to the formation of layers. The conformations observed were compared with that assumed by 1 in its uranyl complex previously reported. Semiempirical molecular orbital calculations have shown that the chair and boat forms have intrinsically similar conformational stabilities. We also investigated by X-ray diffraction and differential scanning calorimetry the phase transition presented by 1.