Louis A. Jones

The reaction of phenylmagnesium bromide with diethyl ether during Grignard preparation

Abstract To determine the Grignard products generated during the preparation of phenylmagnesium bromide in peroxide-free ether, the prepared compound was quenched with H2O or D2O and the products quantitatively determined by gas chromatography and gas chromatography coupled with mass spectrometry. Identified compounds showing no incorporation of deuterium were 1-phenylethanol, 1-ethoxy-1-phenylethane, 1-ethoxy-2-phenylethane, and phenol while those showing hydrogen and deuterium incorporation following D2O quench included benzene, toluene, α-deuteroethylbenzene, biphenyl and terphenyls. Enrichment studies with phenetole suggested that, if produced, it is converted near-quantitatively to phenol while similar studies with 1-ethoxy-1-phenylethane suggested this compound was not the sole intermediate in the chemogenesis of 1-phenylethanol, ethylbenzene and phenetole. It is concluded that phenylcyclidene cosynthetics originate from new Grignard reagents formed by the reaction of the incipient phenylmagnesium bromide and the solvent diethyl ether.

Critical capillary column examination of the relationship between separation number and height equivalent to a theoretical plate and their dependence on temperature

Separation numbers (TZ values) for the homologous pair C11–C12 were determined using a capillary column at 40, 60 and 80°C, as was the height equivalent to a theoretical plate, h, for each hydrocarbon at various linear velocities. Increasing temperatures produced both decreasing TZ and h values, indicating decreased column resolution but suggesting an increase in the number of theoretical plates and hence at a contradictory improved column efficiency. The optimum linear velocity required for producing maximum TZ was shown to be the expected average of that required to produce hmin for C11 and C12. Van Deemter-type plots further suggested an inverse relationship between h and TZ. The following equation was derived: TZ = (L/5.54)12 · [(t1r − tbr)/(tbrh12r + tabh12a)] − 1, where tr is the retention time of consecutive homologues a and b and L is the column length. Results using this equation were compared with those obtained with TZ = [(tbr − tar)/(wa0.5 + wb0.5)] − 1, where w0.5 is the peak width at half-height. The excellent agreement using the data from this study and previous reports clearly shows the concept of TZ to be based on sound chromatographic principles.

Van Deemter-type relationship for determining the optimum initial flow-rate and optimum pressure programming rate in temperature/pressure-programmed capillary column gas chromatography utilizing separation numbers

Accurate prediction of the optimum conditions for a double-programmed gas chromatographic separation (simultaneous temperature and pressure programming) has been accomplished for the first time using a new relationship analogous to that established by the Van Deemter equation. Separation numbers (TZ values) for CH, the homologous pair average [e.g., (C12 + C13)/2 = C12.5], were determined for a C12–C17 series of n-alkanes and related to the average of the elution flow-rate, Fe, of the two homologues used to calculate TZ. Fe is defined as the flow-rate at the time of solute elution. Conditions for analysis involved the selection of a low temperature programming rate (TPR) and four different initial flow-rates (0.677, 1.10, 1.49 and 1.89 ml/min) upon which was super-imposed a series of positive and negative pressure programming rates, PPr. Graphs of TZ versus Fe were parabolic curves which could be described in terms of longitudinal diffusion and resistance to mass transfer. Higher Fes of 1.49 and 1.89 ml/min resulted in straight lines with negative slopes as only resistance to mass transfer was operating. This effect is discussed in terms of laminar and turbulent flow (as predicted by Reynolds number, Re). All plots could be modeled by the quadratic expression TZ = x(Fe)2 + y(Fe) + z. By differentiation, the optimum Fe and maximum TZ for each CH was determined, and, from this, the optimum initial flow-rate PPR could be derived. The example cited is for the data obtained using an initial flow-rate of 0.677 ml/min, a TPR of 0.90°C/min starting at 40°C and nine different PRRs. The optimum initial flow-rate determined under these conditions was found to be 0.80 ml/min with an optimum PPR of 0.12 kPa/min.

A Comparison of Radially-Compressed and Stainless Steel Columns for the Reversed-Phase Ion-Pair Separation of Phencyclidine Synthetic Mixtures

Abstract The reversed-phase ion-pair HPLC separation of phencyclidine synthetic mixtures was optimized utilizing Radial-Pak radially compressed columns. Variables examined in the optimization included column type (C-18, C-8, or CN), pairing ion (methane-, pentane-, hexane-, or octane sulfonates) and mobile phase composition (varying concentrations of methanol or acetonitrile in water). The chromatographic behavior of the phencyclidine mixtures in the various systems utilizing radially compressed columns is compared and contrasted to a similar previous study which examined similar variables on stainless steel columns. The optimum system for radially compressed columns was found to consist of a Radial-Pak C-18 column and a mobile phase of 85:15 MeOH:H2O, 2.5% acetic acid, 1% triethylamine and 5mM sodium hexane sulfonate.

Crystal structure of 4,5-dinitronaphthalic anhydride

The structure of 4,5-dinitronaphthalic anhydride was determined in three dimensions. The molecule is not planar, the carbonyl oxygens being out of the plane of the naphthalene ring system by -0·29 and 0·26 Å. Electronic and infrared spectra seem to indicate that this deviation is not peculiar to the crystalline state. The compound crystallizes in space groupP21/c with unit cell dimensions ofa = 8·096,b = 8·813,c = 15·11 Å, and β = 92·47 °. The finalR index was 5·4%.

Synthesis and Properties of a New Polyether Ketone

SummaryA new polyether ketone has been synthesized (via addition polymerization) by reacting N,N′-bispropargyl-4,4′-diaminobenzophenone and Bisphenol A. The polymer is soluble in both polar and ketonic solvents. The inherent viscosity data indicates the molecular weight of the polymer to be low and thermogravimetric analysis suggests it to be a fairly thermostable polymer.