Dynamics, Thermodynamics, and Time Asymmetry

There are two schools, or lines, of thoughtwhich attempt to unify the apparently divergent laws ofdynamics and thermodynamics and to explain the observedtime asymmetry of the universe and most of its subsystems in spite of the fact that thesesystems are driven by time-symmetric evolutionequations. They will be called the coarse-graining andthe extended dynamics schools (even if these names onlypartially describe their philosophy). The coarse-grainingschool obtains time asymmetry via a projection of thestate space onto a space of relevantstates. The corresponding projection of the primitivereversible evolution laws yields effective irreversibleevolution laws for the relevant states. Extendeddynamics always uses the same primitive reversibleevolution laws. But these laws (in adequate extensionsof the usual spaces where they are formulated)have a set of solutions S that can be decomposed intotwo subsets S₊ and S_- oftime-asymmetric solutions. Time asymmetry is establishedby choosing one of these two sets as the arena in which to formulate thetheory. This paper explains in the simplestself-contained and unbiased way the main characteristicsof both schools and points out the advantages anddisadvantages of each, in such a way as to make explicit thedebate between the schools. Some cosmological featuresof the theory are also considered, mainly the problem ofthe low-entropy initial state of the universe.     

Acid-catalysed,nucleophile-catalysed and thermal decomposition of 2-amino-3-(2′,2′-dimethylaziridino)-1,4-naphthoquinone

The course of the thermal, acid-catalysed and iodide-catalysed decomposition of 2-amino-3-(2′,2′-dimethylaziridino)-1,4-naphthoquinone (III) was investigated. Thermal and iodide-catalysed decompositions gave mainly 2,3-diamino-1,4-naphthoquinone (VI) and 2-amino-3-(2′-methylallylamino)-1,4-naphthoquinone (V) together with low amounts of 2,2-dimethyl-1,2,3,4,5,10-hexahydrobenzo[g]quinoxaline (IV) and 2-isopropyl-1H-naphthoimid-azole-4,9-dione (VII). The acid catalysed isomerization of the aziridinonaphthoquinone III with halohydric acids or with acetic acid readily gave the opening of the aziridine ring; the corresponding salts of 2-amino-3-(2′-haloisobutylamino)-1,4-naphthoquinones (VIIIa-c) and 2-amino-3-(2′-acetoxyisobutylamino)-1,4-naphthoqunone (X) were formed by cleavage of the carbon-nitrogen bond at the substituted carbon atom. Hypotheses on the mechanism of these reactions are given.     

Phase diagrams of crystalline adducts containing two volatile components

The phase relationships in binary systems forming a crystalline addition compound are obtained by means of classical thermodynamic arguments for the case in which both components are volatile. This approach can be applied to inclusion compounds and to other low-stability addition compounds existing only in the solid phase. The results are consistent with those already known for clathrates containing a volatile guest and a non-volatile host, and for symmetric systems, such as racemic compounds. The temperature range in which the adduct undergoes a congruent sublimation depends on the ratio of the vapor pressures of the two components. A relation has been found to exist between the properties of the pure components, the melting behavior and the enthalpy of formation of the adduct.     

Direct mass spectrometry of polymers. XIII.. Thermal fragmentation processes in copoly-α-amino acids

The thermal fragmentation processes in L-Proline—Sarcosine and in L-Proline—L-Alanine copolymers have been investigated by direct pyrolysis—mass spectrometry. The mass spectral data show that proline—sarcosine copolymers decompose in three steps, yielding cyclic oligomers. The first step is characterized by the presence of the Sar—Sar, Sar—Pro, and Pro—Pro cyclic dimers. In the second step the formation of several series of cyclic oligomers up to nonamers—decamers can be observed, while the third step of thermal decomposition process leads to the almost exclusive formation of Pro—Pro cyclic dimer. The proline—alanine copolymers, instead, show a single-step thermal degradation process leading to the formation both of cyclic oligomers and compounds with olefin and nitrile end-groups. Our results show that the thermal decompostion of alanine units is affected by the neighboring units along the polymer chain. Sarcosine units act as thermally labile probes, causing the selective thermal cleavage of the Pro—Sar copolymer.     

Two chrome derivatives from the brown alga Zonariatournefortii

Two minor lipid components of the brown seaweed $\text{Zonaria}$$\text{tournefortii}$ were characterized as (all Z) - 5′,7′-dihydroxy-2′-nonadeca-4,7,10,13,16-pentenyl-chrome chromone ($\text{3}$) and 5′,7′-dihydroxy-2′-pentadecylchrome ($\text{4}$).     

Crystallizable elastomers by chemical modification of transtactic polydiolefins. Hydrochlorination

Solutions of crystalline, high-melting trans-1,4 polybutadiene (trans-PB), trans-1,4 mix 1,2 butadiene-piperylene copolymer (BPC, low piperylene content), and isotactic trans-1,4 piperylene (trans-PP) were partly hydrochlorinated under mild conditions with gaseous HCl. Glass transition and melting temperatures were strongly affected by the addition of HCl. Several hydrochlorinated trans-PB and -BPC were semicrystalline or amorphous elastomers, susceptible to reversible crystallization when stretched. The straininduced crystallinity was similar to that shown by trans-polybutadiene sequences, particularly in the form that is unstable in bulk at room temperature (form II). The addition of HCl to the asymmetric double bond in trans-PP occurs in a stereoselective way, according to ¹³C-NMR. under the experimental conditions of the present study the occurrence of side reactions was observed; these reactions decrease the polymer unsaturation to a lower level than that calculated by the amount of HCl added to the polymer.     

Synthesis of some 2,3-Dihydro-11bH-thiazolo[3,2-d][1,4]benzoxazepin-5-(6H)one derivatives. A new heterocyclic ring system

Condensation of (S)-penicillamine methyl or ethyl ester hydrochloride with salicylaldehyde and its C-5 derivatives, provided the diastereomeric thiazolidine derivatives 1 and 2 . The resulting amino function was acylated to afford the amides 3 and 4. Cyclization of the latter led to the 2,3-dihydro-11bH-thiazolo[3,2-d]-[1,4]benzoxazepin-5-(6H)ones 5 and 6. Conformational data for these heterocyclic compounds are discussed.     

Angle-resolved photoelectron spectroscopy of randomly oriented 3-hydroxytetrahydrofuran enantiomers.

Circular dichroism in the angular distribution of valence photoelectrons emitted from randomly oriented 3-hydroxytetrahydrofuran enantiomers (ThS and ThR) has been observed in gas-phase experiments using circularly polarized vacuum ultraviolet (VUV) light. The measured dichroism for both ThS and ThR, acquired at the single magic angle theta=234.73 degrees and at photon energies of 22, 19, 16, and 14 eV, points to an asymmetric forward-backward scattering of the photoelectrons from their highest occupied molecular orbitals (HOMO) HOMO-1 and HOMO-2, of up to 5%, depending on the photon energy. The asymmetry reverses on exchange of either the helicity of the radiation or the configuration of Th. The photoionization dichroic D parameters of ThS and ThR have been measured and their values discussed in the light of LCAO B-spline density functional theory (DFT) predictions. While an acceptable agreement is found between the dichroic parameter measured and calculated at the highest photon energy for the HOMO and HOMO-2 orbitals of Th, a significant discrepancy is observed for the HOMO-1 state which is attributed to the floppiness of Th, in particular to the comparatively large sensitivity of the size and shape of its HOMO-1 on nuclear vibrational motion.     

Thermodynamics of transfer of non-ionic solutes between immiscible liquid phases. I. Transfer of normal alcohols fromn-octane to water at 25°C

A recently developed calorimetric method has been employed to estimate the thermodynamic functions for transfer of 1-propanol, 1-butanol, 1-pentanol, 1-hexanol and 1-heptanol from n-octane to water at 25°C. A linear correlation for G _t ^o as a function of the number of carbon atoms of the alchohol molecule has been found but for H _t ^o and S _t ^o the dependence gave well defined minima.     

Investigation on the isomerization of 2-amino-3-aziridino-1,4-naphthoquinones to benzo[g]quinoxalines

The course of the hydriodic acid-catalysed and iodide-catalysed isomerization of various 2-amino-3-substituted-aziridino-1,4-naphthoquinones (I) to 1,2,3,4,5,10-hexahydrobenzo[g]-quinoxaline-5,10-diones (III) is investigated, and steric aspects of the reaction are also considered. Only in the case of the phenylaziridino derivative (Ie) does hydriodic acid afford direct cyclization to the corresponding benzoquinoxalinedione (IIIe); in all other cases the hydriodides (V) of the cleavage products (II) are obtained, and liberation of the free bases (II) results in cyclization to the corresponding benzoquinoxalinediones (III) when the aziridine ring is monosubstituted or trans disubstituted, with retention of configuration in the latter case. In contrast, the free bases (II) obtained from cis disubstituted (I) are relatively stable and cyclize with excess iodide yielding trans disubstituted (III). Correspondingly, monosubstituted and trans disubstituted I undergo iodide-catalysed isomerization to III whereas cis disubstituted I do not react.