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Chern. 53,2911Chern. 53, (1975. L'analyse de l'essence dYEriocephalae punctulactus a permis d'isoler deux composCs azuIeniques. Leur structure a kt6 determink sans arnbiguite par spectroscopie r.rn.n. comrne Ctant celle du dimethyl-1,4 azulene et du dimethyl-1,4 ethyl-7 azulene. La r.m.n. du carbone-13 a confirm6 ces structures et nous a perrnis de mettre en evidence sur ces composes ainsi que sur le guaiazulene (dirnkthyl-1,4 isopropyl-7 azulene) des effets de substitution du noyau azulinique.J.-R. LLINAS, D . ROARD, M. DERBESY, and E.-J. VINCENT. Can. J. Chem. 53,291 1 (1975). Two azulene compounds were isolated from the extract of Eriocephalae punctulactus; their structures were determined unambiguously by n.rn.r. as those of 1,4-dimethylazulene and 1,4-dimethyl-7-ethylazulene. These structures were confirmed by I3C n.rn.r. The effects of substitution in the azulene ring on the 13C n.m.r. spectra were demonstrated using these compounds as well as guaiazulene (1,4-dimethyl-7-isopropylazulene). [Journal translation] Dans le cadre de I'analyse effectute sur l'essence d'Eriocephalae punctulactus (encore appelte "plante bleue") en vue de dtterminer ses principaux constituants (ll), nous avons isolt et ttudit deux composts prtsentant les charactbistiques. principales des dCrivts azulCniques (coloration bleue, absorption a 596-603 nm). La skparation de ces produits nCcessite un fractionnement par distillation sur colonne bande tournante suivi d'une chromatographie sur colonne complttt enfin par chromatographie prtparative sur couche mince (11). Par spectroscopie d'absorption dans le visible, les concentrations dans l'essence ont t t t Cvalutes a 0.07% pour le dtrivt 1 et 0.32% pour le dCrivt 2. L'analyse en rtsonance magnttique nuclCaire du proton et du carbone-13 que nous allons dtcrire, nous a permis d'identifier ces deux produits comme &ant le dimkthyl-1,4 tthyl-7 azulbne (dCrivt 1) et le dimkthyl-1,4 azulbne (dkrivt 2). Partie expkrimentaleLes spectres de resonance 'H ont CtC enregistrks sur spectrometre R 32 operant en mode lock6 a la frequence de 90 MHz, en solution dans CC14 (15% vv/) et en presence de TMS pris cornrne reference interne. La ternperature de la sonde est de 30°C. Les dkplacements chimiques ont Ctt CvaluCs avec une prCcision de k0.01 p.p.rn. et les constantes de couplage a 0.1 Hz pres, par simulation de spectre sur ordinateur H P 2100 a l'aide d'une version adaptee du programme LAOCOON 111 (9). Dans certains cas, la prkcision des rnesures a Ct C IimitCe par la presence de nombreux couplages a longue distance infkrieurs a 0.2 Hz. Les rnises en Cvidence d'effet Overhauser nuclkaire ont e t t realiskes sur des solutions 'identiques prkalablement dCgaz6es. Les exaltations d'intensites observCes ont etC rapportkes aux intensites maximales des signaux obtenus soit en I'absence d'irradiation, soit en presence d'une irradiation de m&me puissance a une frequence nettement dCcalee par rapport a la resonance du pic irradik. Les valeurs obtenues ont CtC Cvaluees sur une dizaine dlintCgrations.Les dkpla...

A large number of papers dealing with the computer estimation of thermodynamic properties of real fluids have appeared recently (1-5). Generally; the predicting methods which yield accurate results over a wide range of conditions are quite complex to use and need lengthy calculations on large core memory computers. They are often limited to the prediction of the departure functions. Our purpose was to provide the students and the research staff of our school with a simple and efficient means to evaluate some properties of real gases for computer calculations in applied thermodynamics and chemical engineering. We set up on a small computer, a package of FUNCTION subroutines written in Fortran IV, which were able to calculate separately specific volumes, heat capacities, enthalpy and entropy of a large number of compounds fur a given pressure and temperature. The characteristic ptoperties of these compounds, used in these functions, are stored in a permanent file on disc memory. Principle of ComputationThe method we used involved, first the estimation of the value of the thermodynamic function for the compound in the ideal gas state, and second, the associated isothermal function departure which was derived from a generalized equation of state.Several types of correlations have been used (6-9,24) to obtain analytical expressions for the ideal gas heat capacity ( C p o ) , (9) used a set of thermodynamically consistent equations ((1)-(3)), based on a polynomial development of the fifth degree for the enthalpy H " = A + B T + C T 2 + D T 3 + E T 4 + F T 5 (1) CPD = B + 2CT + 3 D P + 4ET3 + 5 F P (7) So = BlnT + 2CT + 312DP + 413 E F + 514 FT4 + G (3) (Ho = 0 kJ kg-' a t O°K, S o = 0 kJ kg-lK-' at ODK and 1 atm) These equations produce values which fit well with the values calculated by statistical mechanical procedures for 146 gases. Among the numerous generalized equations of state (10-17) which we have tested, we selected the three parameters model of Lee and Edmister (16): This equation (4) was initially intended for the calculation of fugacity coefficients and enthalpy departure of gases. This model gives a good representation of PVT data in a wide pressure and temperature range. I t is very simple to use and can readily he extended to gas mixtures. enthalpy (Ho), and entropy (So). Passut and Danner (8) and Huang and Dauhertwhere T, = critical temperature (OK), PC = critical 'pressure (atm), w = acentric factor, and R = gas constant (82.05606 em3 atm mole-' K-'1. To obtain the specific volume, the compressibility factor (Z = PVIRT) is computed fur each value of P and T by solving the cubic eqn. (14) derived from eqn. (4). In all cases the largest real root was retained.Z3 -ZZ -Z[P2b2/R2T2 + PbIRTo P / R 2 P ] + (abe ) P2/R3T3 = 0 (14)

Abstract-NMR studies on E and 2 enolic phosphates with no substituent on carbon 1 provided evidence for the existence of planar and gauche conformations. When no bulky substituents are present in the cisoid position of the phosphates two planar and twogauche forms are possible. The most stable conformation is the planar form having the phosphate group trans to the double bond. With a bulky substituent in the cisold position of the phosphates the planar form with the group cis to the double bond could not be observed. A close agreement is obtained between the values of dihedral angles determined from observed coupling constants and those calculated with the CND0/2 method. Changes observed in cisoid and transoid *J(POCCH) coupling constants with temperature variation and the reversal of magnitude of these constants when a bulky substituent is on carbon 15* are explained.R6sum6-L'analyse RMN des phosphates d'tnols E et Z non substituts sur le carbone 1, nous a permis de mettre en Bvidcnce l'existence dc conformations planes et gauches. Dans le cas de phosphates ne cornportant pas dc groupcrnent volumincux en position cisolde par rapport au groupement phosphate, il est possible d'envisager dcux formes planes et deux formes gauches. La conformation la plus stable est la formc plane oh le groupement phosphate est en trans par rapport a la double liaison. Dans le cas de phosphates comportant un groupement volumincux en position cisoide, la formc plane oh le groupemcnt est en cis par rapport a la double liaison n'a pu &tre mise en evidence. Un bon accord est obtcnu entrc lcs valeurs des angles diedres des formes gauches dtterminkes A partir des constantes de couplage et calculkes en utilisant la mtthode CND0/2. La variation des constantes *J(POCCH) cisolde et transo1dc en fonction de la temptratwe, a pu &tre justifike et pcrmettra d'expliqucr le renversement apparent dc la valeur de ces constantes lorsquc l'on place un substituant sur le carbone