Reference standards for negative ion mass spectrometry

The negative ion mass spectra of phosphonitrile chlorides (PNCl₂)_n (n≥3) are studied. Since this series of compounds give very intense negative [M]^? and [M? Cl]^? ions, they can be used as good reference standards for negative ion mass spectrometry.     

Electrophilic addition to o-ArY-substituted phenylalkynes. A highly selective cyclization controlled by heteroatoms

Treatment of -(phenyloxy)phenylalkyne with HClO₄ or HBF₄ gave dibenz(b, f)oxepin , whereas the sulfur analogue, -(phenylthio)phenylalkyne , provided 1-phenyl-1-benzothiophenium salts .     

Preparation of polyaryl esters by a new direct polycondensation reaction with arylsulfonyl chlorides in pyridine

Arylsulfonyl chlorides were successfully used as a new condensing agent for the synthesis of polyaryl esters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols. High-molecular-weight polymers (M_w = 84,000) were prepared by reacting dicarboxylic acids with the sulfonyl chlorides in pyridine in the presence of LiCI, followed by treating with a pyridine solution of bisphenols. The polycondensation was significantly affected by factors, such as, the kind of arylsulfonyl chlorides, its amount, the conditions of initial reaction of the acids with the sulfonyl chlorides, the amounts of LiCI added, and dropwise addition of bisphenols.     

Direct polycondensation of aromatic dicarboxylic acids and bisphenols with tosyl chloride and N,N-dimethylformamide in pyridine

A Vilsmeier adduct derived from arylsulfonyl chlorides and DMF in pyridine was successfully used as a new condensating agent for the synthesis of aromatic polyesters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols and also of hydroxybenzoic acids. Polymers of high molecular weights (M?_w = 78,000) with relatively narrow molecular weight distribution (M?_w/M?_n ≈ 3.0) were prepared by reacting aromatic dicarboxylic acids with the adduct in pyridine, followed by addition of bisphenols. The polycondensation was significantly affected by the amount of DMF, the nature of the arylsulfonyl chlorides, the conditions of initial reaction of the acids with the adduct, and the rate of reaction with bisphenols. The process was adaptable to the direct polycondensation of hydroxybenzoic acids, affording polymers of high molecular weight (η_inh = 1.73).     

Kinetics of polymer decomposition

Kinetic equations have been developed for polymers that decompose by the zipper mechanism. The usual assumption of steady state kinetics has not been made. Plots of the fraction decomposed α, as a function of time demonstrate a variety of patterns depending upon the relative values of the fraction k₁, of chains becoming activated per second and the fraction k₂ of an activated chain that decomposes per second.     

Flameless atomic absorption spectrometry of antimony

Flameless atomic absorption spectrometry of antimony has been investigated with a carbon rod device. Antimony may be determined in solution at a level of 10^-10 g with a sample volume of 0.5 μl. Optimal conditions and interferences are described. Matrix effects on antimony necessitated a preliminary solvent extraction of the chloride complex from hydrochloric acid solution containing nitrite with methyl isobutyl ketone. The determination of antimony in metallurgical samples was shown to be satisfactory.     

Kinetics of the decomposition of poly(vinyl chloride)

Equations derived on the basis of a zipper mechanism under conditions where steadystate kinetics did not apply were found to represent the kinetics of the thermal decomposition of poly(vinyl chloride) in the temperature range 220–240°C.