Dipole moments and molecular conformation in aliphatic diazoketones

The dipole moments of diazoacetone RCOCHn₂ and its three chloro derivatives substituted at the alkyl group have been determined. The experimental values are consistent with a rigid planar structure of the COCHN₂, where the CO and CN₂ groups may be either in cis or trans configuration In the parent molecule, an equilibrium is operative between the two and in the halogenated derivatives the cis configuration only is present. As to a possible free or hindered rotation of the halogenated alkyl group R around the R—Co bond, a comparison between found and calculated dipole moment values, and a qualitative consideration of internal steric and electrostatic factors, suggest that a single steric configuration is preferred in the monochloro and dichloro derivatives. The angle of 150° and 40° between the molecular plane containing the COCHN₂ grouping, and the plane defined by the C(carbonyl)—C(alkyl)—X(X = Cl in the former, H in the latter molecule) was found. A similar rigid structure is also expected in the parent molecule and, to a greater extent, in its trichloro derivative.     

The surface tension and surface potential of aqueous solutions of normal aliphatic alcohols

Surface tension and surface potential measurements have been made as functions of concentration and temperature for a homologous series of normal aliphatic alcohols. The results are fitted to a two-dimensional equation of state and the surface tension measurements are checked for consistency with the corresponding surface potential results. From the temperature dependence of the surface tension the quantities ΔH⁰. ΔS⁰, and ΔG⁰ for the adsorption process are calculated. These results are correlated with corresponding solution thermodynamics. The molecular configuration in the surface has been tentatively deduced. The surface phase more closely resembles the bulk solution than the vapor. The negative entropy of adsorption from the vapor is very large and it is suggested that the additional factors responsible for the high values are changes in internal degrees of freedom of the hydrocarbon portion of the molecule, and “cluster” formation in the water in the immediate neighborhood of the solute molecule.     

Ice nucleation by monolayers of aliphatic alcohols

Monolayers of aliphatic long chain alcohols (C_nH_2n+1OH) were found to induce nucleation of ice at temperatures approaching O°C in contrast to water-soluble alcohols which are efficient antifreeze agents. The corresponding fatty acids and alcohols with bulky hydrophobic groups, induce ice nucleation at temperatures lower by as much as 12°C. The freezing point induced by the amphiphilic alcohols was found to be sensitive not only to area per molecule but also to chain length and parity, reaching higher temperatures for monolayers with n odd. Grazing incidence X-ray diffraction studies performed on some of these alcohols at the air/water interface (at 5°C and at zero pressure), demonstrated the formation of crystalline two-dimensional clusters with a distorted hexagonal cell whose dimensions resemble those of hexagonal ice. The catalysis of ice nucleation by these alcohol monolayers may be rationalized in terms of the structural match between the monolayer domains and the ab layer of hexagonal ice.     

Photoionization mass spectrometry of aliphatic monoterpene alcohols

Summary 1. The dissociative processes observed in the photoionization of monoterpene alcohols have been investigated. It has been established that the relative intensities of the peaks of the heavy ions, including the molecular ions, are higher on photoionization than on electron impact.2. It has been found that the mass spectra of the isomeric alcohols obtained on photoionization differ from one another to a greater degree than the electronic mass spectra.Agrophysical Scientific-Research Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 723–726, November–December, 1974.     

Mass spectra of branched long-chain aliphatic alcohols

The mass-spectral behaviour of long-chain aliphatic primary alcohols of the normal, iso-and anteiso-series have been discussed. The mass-spectral fragmentation of individual alcoholic types have been found to be structurally specific. The mass spectra of some deuterio derivatives have shown, however, the complicated nature of the fragmentation processes.     

Mitsunobu reactions of aliphatic alcohols and bulky phenols

Alkylation of hydrazinedicarboxylate (a Mitsunobu by-product) is not a notable problem in common Mitsunobu alkyl aryl etherification reactions. Good yields can be obtained with a wide range of solvents. However, this side reaction can cause yield reduction for the reactions of sterically hindered phenols and primary alcohols. To suppress the side reaction, solvent effect was investigated. It was found that hydrazinedicarboxylate is about five times less soluble in diethyl ether than in THF, and the yields are improved for ortho-substituted phenols of a wide range of steric hindrance using diethyl ether as the solvent instead of THF which is the more commonly used for Mitsunobu reactions.     

Copper-catalyzed coupling of aryl iodides with aliphatic alcohols

[reaction: see text] A simple and mild method for the coupling of aryl iodides and aliphatic alcohols that does not require the use of alkoxide bases is described. The reactions can be performed in neat alcohol. For more precious alcohols, the etherification was carried out in toluene as solvent using 2 equiv of alcohol. Additionally, the cross-coupling of an optically active benzylic alcohol with an unactivated aryl halide was demonstrated to proceed with complete retention of configuration.     

In-beam electron impact mass spectrometry of aliphatic alcohols

The characteristics of the in-beam electron impact mass spectra of six isomers of undecanol as well as several 1-alkanols have been examined. In addition to the characteristic ions observed in the conventional electron impact spectra, the [2M+1]⁺, [2M+1-H₂O]⁺, [2M+1-2H₂O]⁺, [2M-R or R′]⁺, [2M-H₂O? R or R′]⁺, [2M? 2H₂O? R or R′]⁺ and [M+1? H₂O]⁺ peaks are common in the in-beam electron impact mass spectra of the undecanol isomers of structure RCH(OH)R′. Deuterium labelling experiments have shown that the extra proton in the protonated dimer ions, [2M+1]⁺, originates from the hydroxy group. The processes which produce the important peaks in the high m/e regions are discussed.     

Reactions of 1,3,5-trinitrobenzene with primary aliphatic alcohols

Analysis of reactions of 1,3,5-trinitrobenzene (TNB) with alcoholates of primary aliphatic alcohols (substitution of the nitro group or generation of σ^H-complexes at the unsubstituted position of TNB) leads to the conclusion that high basicity of alcoholates (MeONa, EtONa) of unsubstituted primary alcohols promotes formation of σ^H-complexes, thus preventing nucleophilic substitution of a nitro group. Introduction of electron-withdrawing substitutes (R = HC≡C, H₂C = CH, pyridyl) into the alcohol molecule (RCH₂OH) reduces the basicity of their alcoholates which makes substitution of nitro groups possible aff ording the corresponding 1-alkoxy-3,5-dinitrobenzenes in the presence of K₂CO₃ in N-methylpyrrolidone at 80 °C.