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The rates of hydrogen-deuterium exchange of protons alpha to the sulphonyl group in a conformationally rigid sulphone have been measured in aqueous-DMSO. The exchange rate ratio k eq: k ax is 1·6. The greater kinetic acidity of the equatorial proton is in accord with recent MO calculations on sulphonyl carbanion stability, but does not preclude the intermediary of planar species.

A series of 1-substituted-3,5-dimethyl-4-piperidones has been prepared and the positions of cis-trans equilibria determined by NMR. The equilibrium constants for the 1-(p-substituted phenyl) compounds do not vary significantly with the para substituent and are similar to the equilibrium constant for the 1-t-butyl analogue.

Motilin, a polypeptide isolated from the mucosa of the upper meter of small intestine of the hog has been purified. The polypeptide contains 22 amino acid residues and has a calculated molecular weight of 2700. The following amino acid composition has been determined: Arg 2, Asn/Asp 1, Gln/Glu 6, Gly 2, Ile 1, Leu 1, Lys 2, Met 1, Phe 2, Pro 1, Thr 1, Tyr 1, Val 1. The N-terminal amino acid residue has been confirmed to be phenylalanine. Digestion of the molecule with carboxypeptidase A has revealed the C-terminal residues to be glycine and glutamine, the latter occupying the C-terminal position. Motilin is chemically different from all identified gastrointestinal polypeptides.

Four 4-hydroxyisoxazoles together with model compounds have been investigated by UV, IR and NMR spectroscopy and by p K a measurements, 4-Hydroxyisoxazoles exist predominantly in the hydroxy-form in a wide range of media.

A graphical treatment of coupling constant data from a number of substituted 2,3-dihydropyran systems has afforded information about the conformational equilibria within the series. Small changes in structure alter the conformational equilibrium significantly. Some trisubstituted dihydropyran rings prefer to exist in the conformer with all three groups in the pseudo-axial position.

Radioactive microspheres were used to measure ovarian and regional blood flow in unanesthetized estrous and pseudopregnant rabbits. Ovarian blood flow was 5 times higher on Day 9 of pseudopregnancy (9.4 ml. per gram per minute) than before ovulation (1.7 ml. per gram per minute). The corpora lutea received more than 80 per cent of the total ovarian blood flow and accounted for the postovulatory hyperemia. Intravenous injection of prostaglandin F 2α (PGF 2α ) caused a significant redistribution of ovarian blood flow; corpus luteum blood flow decreased while blood flow to the interstitial and follicular tissue increased. Our results suggest that prostaglandins play a role in regulating the ovarian microcirulation and that PGF 2α constricts the afferent blood vessels of the corpus luteum or small arteriovenous anastomoses.

Ionisation data for a series of phenol indicators are used to define H m values for non buffered ( H m 16·4-13·9), phosphate buffered (14·0-12·2) and borate buffered (13·5-11·2) solutions of tetramethylammonium hydroxide and methoxide mixture in methanol. The dissociation constants of the phenols in methanol are also reported.

A retrospective study was conducted from May to July 1973 among all Thai men who had been vasectomized at Ramathibodi Hospital Bangkok between January 1970 and March 1973 in order to determine their physical psycho-social and sexual responses to the operation. 63% of the men responded to an invitation to be interviewed at the hospital. Their man age was 33.5 years and 86.5% were less than 40 years of age. The mean duration of marriage was 8.4 years. The vasectomized men were a relatively well educated group; half of them had at least some secondary school education. 48.1% of the men cited friends and relatives as the original source of information about vasectomies. 22.2% learned about them from mass media. The major reasons given by the men in the study for obtaining a vasectomy were economic in nature. 68% of the men reported that they or their wives had practiced some form of birth control prior to the vasectomy operation. 45.9% of the men had the operation when they reached their expressed ideal number of children and 28.1% were vasectomized after they had exceeded their ideal. Almost all of the men reported little or no pain during the operation and after the operation the great majority reported that they had no problems. All but 1 of the men said that they would select vasectomy again as their method of birth control. The overwhelming majority of the respondents reported that their health was either the same or better since the operation. The most significant negative factors associated with health was fatigue. Most of the men stated that they were happier and more comfortable since the operation. 20% said that they were more irritable since the operation. The quality of their relationships with their wives and in the work situation seemed to be relatively unchanged. Post vasectomy changes in sexual relations were found to be minimal; if occurring at all such changes were usually improvements. It was concluded that vasectomy is a safe effective and uncomplicated procedure for permanent fertility control.

The introduction of eight alkoxy or eight alkyl substituents onto the phthalocyanine (Pc) nucleus at the non-peripheral (1,4,8,11,15,18,22,25) positions produces derivatives which are soluble in a variety of organic solvents. However, other physico-chemical properties of the two series differ. Octa-alkyl derivatives, R8 Pcs, pack as more ordered molecular assemblies in the solid state and show thermotropic liquid crystal behaviour with transition temperatures dependent upon substituent chain length and the central metal atom. In contrast, octa-alkoxy materials, (RO)8 Pcs, melt directly into the isotropic liquid. The latter can be deposited as Langmuir-Blodgett films whereas the former cannot. Experiments with examples of the two series in which one or two of the chains are functionalized at the terminal positions with a hydrophilic moiety show that these amphiphilic analogues deposit well by the Langmuir-Blodgett method. A number of the films show a high degree of molecular ordering, as judged by X-ray reflectivity methods, transmission infrared, RAIRS and polarized optical spectroscopy. Results indicate that the type of ordering is controlled by the type of substituent and the length of the chain.

An evaluation is presented of the TEMPER model as a representation of, and a tool for, the analysis of international relations. The major assumptions implicit in the model were examined and assessed to determine their degree of scientific validation, relevance to problems of crisis management, and relevance to decisions of the U.S. and the Department of Defense. Equations and computer routines dealing with political aspects of the model were analyzed. Recommendations were made to eliminate, modify or combine routines, correct errors and ambiguities, and simplify propositions embedded in the model. Strengths and novel features of the TEMPER design were also identified. The most radical recommendation in this report is to transform TEMPER into a family of partial models for man-machine interaction in the analysis of international crisis. Time-sharing now makes this practicable. TEMPER is potentially a powerful device for the study of international relations.

Publisher Summary This chapter discusses aromaticity of heterocycles. At a time when the validity of the concept of aromaticity is questioned, increasingly, it seems appropriate to review various definitions in common use and to survey their applications in heterocyclic chemistry. From a qualitative viewpoint the characteristics of an aromatic compound are easy to define. A compound is said to be aromatic if it is cyclic and unsaturated with an enhanced stability over simple olefinic compounds. The characteristic aromatic reactivity of the type described is clearly a matter of degree and is difficult to assess quantitatively. From a simple consideration of pyridine, which reacts less readily with electrophiles but more readily with nucleophiles at the ring carbon atoms than does benzene, it soon becomes apparent that attempts to discuss even relative aromatic character using kinetic criteria is fraught with difficulties; this is apart from the fundamental objection that chemical reactivity is not solely a function of ground-state stability.

The 220 MHz spectra of the title compounds are reported and values for the internal ring dihedral angle, Ψ, formed between the C-2C-1 and C-3C-4 bonds, calculated using the R-value method. The trimethyltetralone exists in a conformer having Ψ = 51° and the 4-methyl group in the axial position. 4-Methyl-1-tetralone exists in a conformational equilibrium where the mean value of Ψ for the conformers adopted is 56°.

Tautomeric equilibria in the heteroaromatic and the analogous saturated series are compared. Available methods of conversion of free energy ΔG° into enthalpy ΔH° terms are applied and discussed. The ΔH° values obtained are used to demonstrate that 2-pyridone and 2-pyridinethione retain most of the aromatic resonance energy of pyridine, that 2-pyridone imine is also strongly aromatic, but that 2-pyridone methide is far less so. The work is compared with other estimates of the aromaticity of these compounds.

Aromatic resonance energies for 4-pyridone and its analogues are similar to those for the 2-pyridone series. For the bicyclic compounds, the differences in aromaticity between the quinolinoid and the quinolonoid forms are significantly less than for the monocyclic derivatives. A new acidity function H–(q) is derived for the deprotonation of methyl quaternary salts to netural heterocyclic methide and imine bases. Quantitative tautomeric ratios are reported for the thioamide–thioimidate equilibrium in an Appendix.

Dipole moments and n.m.r. data for 1,3-dithian 1-oxide, its 2,2-dimethyl derivative, and certain conformationally rigid 1,3-dithian 1-oxides are reported. The results, together with u.v. data for 1,3-dithian 1-oxide and its cis-and trans-2-t-butyl derivatives, demonstrate that the mobile compounds exist predominantly as the conformer with the SO bond equatorial. The direction of the sulphoxide dipole moment is discussed.

U.v. spectra of the pyridinoid title compounds and of models for the corresponding pyridonoid tautomers show that the pyridinoid tautomeric forms are greatly preferred in aqueous solutions. pKa Measurements allow quantitative determinations of tautomeric equilibrium constants which are compared with data for various other systems; the latter data include new results for some enamine–imine equilibria. The aromatic character of the pyridonoid forms of the title compounds is discussed.

The tautomerism of acyl- and sulphonyl-amidines is reviewed. The structures of the cations of mobile and fixed forms of acetyl-, benzoyl-, mesyl-, and tosyl-amidines are established by u.v. spectroscopy. Quantitative pKa measurements demonstrate that the H2N–CRN–Y form predominates for all series with KTca. 30 for the acyl- and ca. 107 for the sulphonyl compounds.These results are compared with the tautomerism of 2-acylamino- and 2-sulphonamido-pyridines, and differences in tautomeric behaviour are rationalised.

Consideration of tautomeric equilibria allows the estimation of the aromatic stabilization energy of 2-pyridone as 25 kcal mol–1: the method is applied to related compounds.

Thermodynamic parameters for the protonation of nine substituted pyridines and nine azine N-oxides are obtained from basicity measurements of the bases at 25, 40, 60, 80, and 90° using the spectrophotometric method. The protonations of both series of bases follow linear ΔH0–pKa correlations. The spectrophotometric measurements are also used to assess the temperature variation of the H0 and HA acidity functions and the relationship HA=mH0+C is found to be approximately temperature independent.