Search results for "Carboxylic group"

Reversible switching of the electronic ground state in a pentacoordinated Cu(ii) complex.

2013

International audience; An easy reversible switching of the electronic ground state in a pentacoordinated copper(ii) complex is reported for the first time. The simple protonation of a carboxylic group in a Cu(ii) complex with a {dx(2)-y(2)}(1) electronic configuration leads to a flip of the ground electronic configuration from {dx(2)-y(2)}(1) to {dz(2)}(1) in the metal ion.

Photoinduced functionalization of diterpenes: photochemical behaviour of grandifloric acid in methanol and acetonitrile

2004

Abstract Irradiation of grandiflorolic acid (11) at λ=254 nm in acetonitrile gave the two epimers 13 and 14 through a photodecarboxylation reaction of the carboxylic group on C-4. Irradiation of compound 11 in methanol at λ=254 nm provided the transformation of the C-20 angular methyl into a carbomethoxymethyl group. In this case, unlike compounds 13 and 14, only one of the two possible isomers (15) was obtained (equatorial methyl at C-4). A mechanistic approach of this reaction in discussed, and the role of mutual stereochemistry between C-20 methyl and C-19 carboxylic group in determining the course of the reaction is pointed out.

1973

The thermal degradation of poly(oxycarbonylethylene) (poly-β-propiolactone) has been investigated within a temperature range of 180–220°C and under various pressures. The degradation begins with a considerable decrease in molecular weight, followed by an accelerating formation of acrylic acid. The reaction involves the following steps: 1 Random chain scission of polymer chains by typical ester pyrolysis with the formation of fragments one of which containing a carboxylic group the other one a CC-double bond at the chain end (Eq. (1)). 2 Formation of the volatile acrylic acid by scissions at the chain end, the amount of acrylic acid or the weight-loss increasing with the number of fragmentat…

Über die photosensibilisierte autoxydation von polyvinylalkohol

1968

Polyvinylalkohol wurde in wasriger Losung bei 30°C unter Belichtung mit einer Quecksilberhochdrucklampe einer mit benzophenn-3.3′-disulfonsaurem Natrium photosensibilisierten Autoxydation unterworfen. Als Reaktionsprodukte wurden Wasserstoffperoxid, Sauren und Kohlendioxid ermittelt. Unter den gewahlten Reaktionsbedingungen werden die Makromolekule statistisch abgebaut. Viskositatsmessungen und analytische Bestimmungen zeigen, das pro Spaltung der polymerkette nur eine Carboxylendgruppe entsteht. Ein Reaktionsmechanismus wird diskutiert. Polyvinylalcohol was oxidized in water solution at 30°C by irradiation with a mercury high pressure lamp and benzophenon-3.3′-disodiumdisulfonate as sensit…