A New Approach to δ-Phenylvaleric Acids

Abstract

NOTES 5527 0.40 to 3.24 mm. I n only three attempts was any decrease in pressure whatsoever observed and the average of these three decreases was only 0.02 mm. It may be concluded that no rapid polymerization occurs during the period 3 seconds-45 minutes after the gas leaves the discharge. It was not possible to detect any long-time (one or two days) pressure changes arising from slow decomposition, because of insufficient stability of the Bourdon gage over long periods.The results of several measurements of the pressure change resulting from the decomposition of the monoxide to sulfur and SO2 are summarized in Table I. TABLE I PRESSURE DECREASE ON DECOMPOSING SULFUR MONOXIDE Initial P(mm.) Final P(mm). Decrease, % 0.14 0.09 36 .26 .21 19 .44 .32 18 .56 .38 32 .63 .57 10 .64 .44 31 .70 .64 9 .70 .54 23 .71 .62 13 .94 .63 33 1.15 .48 58 Average 26To ensure that the changes were really due to the presence of sulfur monoxide, seven measurements were made on SO2 alone, three on ,302 passed through the discharge in the absence of sulfur vapor, and one on SO2 to which was added sulfur vapor in the absence of the discharge. The average change for these eleven experiments was a decrease of 0.1% with a probable error of 1%.The large variation between samples in the observed pressure changes is mainly the result of variation in sulfur monoxide content. Qualitatively it was noted that when the deposit in F was more intensely colored, the pressure decrease was greater. Also the relative proportion of molecular species in the gas might be quite variable in a mixture suddenly withdrawn from the reaction zone and "frozen" in a metastable condition. Thus the average decrease of 26% has no quantitative significance other than to show that the change is far greater than the experimental error of the control experiments and to demonstrate that a considerable part of the gas is responsible for the effect. From the average sulfur monoxide content i t may be estimated that a typical gas sample contains about 70% monomeric SO, but a wide variation from this typical value is probable.It is strongly indicated by these experiments that the product from the discharge is a mixture of SO and SZOZ which undergoes no appreciable further dimerization after removal from the discharge tube and holding a t room temperature 45 minutes. It is not surprising that Kondrat'ev's contention of complete dimerization is contradicted; his arguments rest almost entirely upon experiments conducted in the presence of H2S and 0 2 at total pressures as high as 100 mm. and catalysis of the dimerization may be very important. The existence of monomeric SO should not be considered established, however, until the uncertainties in the analytical methods for the gas mixture and decomposition products are entirely removed and until the question of the absence of a characteristic infrared absorption is solved.Experiments upon the paramagnetism of the gas would be instructive, if such measurements could be carried out on a compressed sample before it underwent decomposit...

First Synthesis of <I>N</I>-(4-Fluorophenyl)-5-(4-fluorophenyl)-2-(4-hydroxybenzyl)pentanamide, a New Potential Cholesterol Absorption Inhibitor

“…The condensation of 4-¯uorobenzaldehyde (3) with diethyl ethylidenemalonate under alkaline conditions gave the diacid 4 after ®nal acidi®cation with dilute hydrochloric acid (Gardner et al 1952;Ebine et al 1968). The yellow cinnamylidene malonic acid (3) was rapidly reduced to 2-[3-(4-¯uorophenyl)propyl]malonic acid (5) using a treatment NiCl 2 , 6H 2 O±NaBH 4 in methanol (Nose & Kudo 1984;Ganem & Osby 1986).…”

Derivate des 1.3-Benzdioxols, 51 Darstellung und Reaktionen des 6.7.8.9-Tetrahydrocyclohepta[4.5]benzo[1.2-d][1.3]dioxol-5-on / Derivatives of 1,3-Benzodioxoles, 51 Preparation and Reactions of 6,7,8,9-Tetrahydrocyclohepta[4.5]benzo[1,2-d][1,3]dioxol-5-one

“…Bei größeren Ansätzen führte diese M ethode zu einer Reihe von N ebenprodukten und dam it zu chromatographisch schwer auftrennbaren Gemischen. Erfolgreicher verliefen die U m setzun gen der Aldehyde l a -e mit dem Ethylidenmalonester [7], vor allem dann, wenn man an Stelle des em pfohlenen Triton B [8] Tetramethylammoniumhydroxid als Base verwendete. Die hierbei erzielten A usbeuten an den Dicarbonsäuren 2 a -e lagen zwi schen 72 und 90%.…”

Total synthesis of a curvularin isomer

“…3,5-Dimethoxybenzaldehyde was condensed with ethylidene malonate diethyl ester (9) to yield a diene diacid. Hydrogenation of double bonds, and decarboxylation resulted in the production of the desired pentanoic acid which was cyclized with anhydrous hydrogen fluoride to ketone 5.…”