No abstract

Research has shown that certain weed species are suppressed by rye (Secale cereale L.) used as a mulch or cover crop in no-tillage cropping systems. To determine whether this suppression was caused by phytotoxic compounds, an aqueous extract of rye was partioned with diethyl ether-ethyl acetate, the organic phase was separated by preparative TLC, and biologically active bands were removed, extracted, and further separated by reversed-phase high-performance liquid chromatography. The collected fractions were evaporated and silyl and deuterated silyl derivatives prepared and analyzed by gas chromatography/mass spectrometry. Identified were two compounds not previously implicated in allelopathy, /3-phenyllactic acid (/3-PLA) and /3-hydroxybutyric acid (/3-HBA), noninhibitory succinic acid, and three other unidentified acids. Biological testing indicated that /3-PLA was more inhibitory than /3-HBA to hypocotyl and root growth of Chenopodium album and Amaranthus retroflexus. The isomeric a-PLA proved to be 17 times more active than /3-PLA to hypocotyl growth to A. retroflexus.

The experiment in this paper was developed in order to resolve the tension between the importance of HPLC versus the high lab cost to execute the experiment.

Long-Chain Hydrocarbons of Cannabis and Its Smoke A series of long-chain paraffins has been identified in Cannabis and its smoke by gas chromatography and mass spectrometry. The level of hydrocarbons was determined to be about half that found in tobacco and its smoke, although the effect of smoking on the paraffins in the Cannabis plant material was comparable to analogous studies of tobacco and its smoke.

The preparation of 5-nitroacenaphthene (2) using several nitrating agents resulted in a product which was found to be contaminated with 20-30% of the 3-nitro isorneride. Separation was accomplished by t.1.c. and the n.m.r. spectra of the isomers are now reported. A new synthesis of 4,s-dinitronaphthalic anhydride (5) and an improved preparation of the dimethyl and diethyl esters of 4-nitronaphthalic anhydride and 5 is described. The esters were converted to the corresponding diarnino derivatives by high pressure hydrogen-Pd reduction.