N-substituted Groups Research Articles

Conformational behaviors of N-substituted N-lauroylglycinates in aqueous micellar and DMSO solutions and their Krafft points

The 13C and 1H NMR spectra of N-lauroylglycines and/or their sodium salts substituted at the peptide nitrogen atom, CH 3(CH 2) 10CON( X)CH 2COOH/or Na; X =H, CH 3, CH 2CH 3, (CH 2) 2CH 3, (CH 2) 3CH 3, (CH 2) 2OH, and (CH 2) 3OH, were measured in DMSO- d 6 and D 2O solutions. The existence of both cis and trans isomeric forms of peptide groups was observed for all the surfactant samples except N-lauroylglycine ( X =H) and its sodium salt, which were present only in the trans conformation. The population of the trans isomer in DMSO- d 6 solutions decreases monotonously as the alkyl chain length of N-substituent becomes longer. It is interesting to note that the population of the trans isomer in aqueous micellar solutions decreases with the increasing chain length of N-hydroxyalkyl groups but unexpectedly increases with the size of N-substituent in the case of N-alkyl groups. The conformational behaviors of these surfactant molecules in the micellar aggregates may be explained in terms of the steric and hydrophobic interactions between the N-substituted groups and the long N-acyl chain. The Krafft points of the calcium salts of surfactants were found to be markedly depressed with increasing chain length in N-substituted groups. Sodium N-hydroxypropyl- N-lauroylglycinate especially shows the Krafft point to be lower than 0°C even in hard water and is useful as a surfactant, being applicable in hard and/or cold water.

SYNTHESES OF POLYMER-BOUND RHODIUM COMPLEXES AND THEIR APPLICATION AS CATALYSTS FOR THE HYDROFORMYLATION OF DIISOBUTYLENE (II)

Five kinds of polymer-anchored aminophosphine-rhodium complexes were synthesizedby ionic and covalent bonding methods. These anehored rhodium complexes synthesizedpossess good catalytic activity and aldehyde-formation selectivity in the hydroformylationof diisobutylene. The complexes anchored via covalent bonds on polymers showedexcellent reproducibility on recycling. After reaction, it indicated that the loss of rhodiumof the catalysts was very small as shown by analysis.

Torsional angles in N-substituted benzamides and related compounds by carbon-13 N.M.R. chemical shifts

The torsional angles in 30 N-substituted benzamides and related compounds have been estimated by the use of the 13C substituent chemical shifts of the meta and para carbon atoms. Steric interaction between the N-substituted groups and the ortho hydrogen atoms of the benzene ring is the major determinant of non-planarity in these systems. A linear relationship between steric substituent constants of the N-substituted groups of some benzamides and the torsional angles is proposed. Dynamic processes involving rotation about the C-N bond, nitrogen inversion and ring inversion contribute a dynamic steric effect to the overall steric interaction. The preferred conformations of some N-substituted groups is also discussed.

13C-NMR studies on 1-N-[(S)-4-amino-2-hydroxybutyl]kanamycin A (butikacin) and related aminoglycosides.

The 13C-NMR spectra of 1-N-[(S)-4-amino-2-hydroxybutyl]kanamycin A (butikacin) (Fig. 1, 1b) and some of its related compounds have been recorded and are tabulated, assigned and discussed. The chemical shifts of many of the carbon nuclei are shown to be reasonably invariant amongst this series of compounds. A procedure is described for the determination of the (R,S)-epimer ratio of kanamycin A derivatives which have N-substituted groups containing a chiral centre.

On the specificity of the Folin and Lowry reagents for amine derivatives

Reactivities of several amine derivatives with the Folin and Lowry reagents were examined. Tertiary amines reacted with the Folin reagent to produce a blue color, and secondary amines having a 2-hydroxyethyl group reacted with the Folin reagent only in the presence of Cu 2+, i.e., with the Lowry reagent. On the other hand, primary and quarternary amines and amine N-oxides produced no color with either reagent. Reactivities of tertiary amines were greatly influenced by the nature of the N-substituted groups, and the color yield of those forming stable chelate complexes with metals was strongly inhibited by the presence of Cu 2+, indicating that the formation of a stable complex with Cu 2+ reduces the reactivity of tertiary amino nitrogen. The requirement of Cu 2+ for the color development with secondary amines having a 2-hydroxyethyl group may be due to the formation of weak chelate complex with Cu 2+.

Inclusion complexes of .BETA.-cyclodextrin with tranquilizing drugs phenothiazines in aqueous solution.

The interaction of tranquilizing drugs phenothiazines with β-cyclodextrin in aqueous solution was studied by circular dichroism, ultraviolet (UV) absorption, and proton magnetic resonance spectroscopies. The induced circular dichroism bands and UV absorption changes were quantitatively investigated and stoichiometric ratio, which was found to be 1 : 1, and formation constants of inclusion complexes were obtained. In β-cyclodextrin-drug system, protons located in a cavity of β-cyclodextrin were found to be subjected to anisotropic shielding, while protons of phenyl and N-substituted groups in the drug shifted to low field, in which all peaks caused remarkable broadening. Formation constants were correlated well with partition coefficient of drug and also with the magnitude of proton magnetic resonance spectral broadening. These spectral changes strongly suggested that aromatic portion of drug was included into hydrophobic cavity of β-cyclodextrin, while N-substituents of drug interacted with the outside groups of β-cyclodextrin cavity.

A study of the inhibiting properties of some derivatives of thiourea

Polarization of mild steel in 0·1 and 1·0 M hydrochloric acid in the presence of derivatives of thiourea has been studied at various inhibitor concentrations. The inhibition efficiency of the compounds was related to the properties of the polar groups and the size of the N-substituted groups. A mechanism for high adsorption and inhibition of S-containing compounds based on the principle of hard and soft acids and bases is suggested.

Functional group and substituent effects, both steric and electronic, upon the ultraviolet absorption spectra of some N-alkyl- and N,N-dialkyl-derivatives of some cinnamamides and benzalcyanoacetamides

Conjugative and steric constants for N-substituted carboxyamide groups have been derived which allow the calculation of the long wavelength absorption maxima of N-alkyl- and N,N-dialkyl-derivatives of cinnamamide and benzalcyanoacetamide. Deviations between calculated and observed values indicate that there may be steric interference between bulky N,N-dialkylcarboxyamide groups and the benzylic hydrogen atom.