Malonic acid photolysis

Carbon suboxide, C3O2, 0=C=C=C=0 , also called l,2-propadiene-l,3-dione, is an evil-smelling unstable gas, bp +6.8 °C, which is obtained by the dehydration of malonic acid with P4O10 in vacuum at 140-150 °C (equation 6). Carbon suboxide polymerizes readily at room temperature to a yellow solid, and above 100 °C to a ruby-red water-soluble solid. Photolysis of C3O2 gives C2O ( C=C=0 ) as a reactive intermediate, which reacts with alkenes by carbon atom insertion (equation 7). 

Photolysis of spirocyclic malonyl peroxide 34, prepared from the corresponding malonic acid, at 350 nm in methanol leads to an almost quantitative yield of a 1 1 stereoisomeric mixture of 9-methoxybicyclo[6.1.0]nonane-9-carboxylic acid (35). ... 

The results of a study of the photolysis of the uranyl-malonic acid-bimalonate system suggest that the primary photosensitive species is a (1 1) uranyl bimalonate complex, which forms as a precipitate. Kinetic and other evidence supports the mechanism shown in equations (10)—(13), where Mai = malonate. 

Copper.—The labile complexes [Cu(mal)2]2- and Cu(mal) (mal = malonate) undergo photolysis in solution to give acetate and carbon dioxide but Cu" is not permanently reduced.129 On flash photolysis, however, transient species assigned to Cu1 compounds were observed. Cu11 derivatives of carboxylic acids have been used in the preparation of photosensitive plates.130... 

Photolytic and catalytic decomposition of a-diazo esters produces )8-lactones, which are formed via intramolecular C—H insertion of a carbene or carbenoids. Tertiary alkyl esters of diazomalonic acid are decomposed by rhodium acetate with exclusive formation of the four-membered ring 211. This suggests a smooth insertion into the C—H bond activated by the adjacent oxygen atom (90TL1023). jS-Lactone 212 was obtained by photolysis of diazo malonic ester 213 (71CC577). 

Monocyclic Selenophens.—Selenophen has been prepared from butadiene and selenium dioxide. Selenophen-3-malonic esters have been prepared by condensation of l,4-dichlorobut-3-en-2-one with malonic esters followed by reaction with sodium selenide and cyclization. 2-(2-Selenienyl)-3,4-dicarbeth-oxyfuran has been prepared analogously to the thiophen derivative.The transient absorption spectra in the flash photolysis of selenophen have been studied. "" Butyl-lithium and phenyl-lithium attack 2,5-dimethoxyselenophen at the selenium atom, giving dibutyl selenide and diphenyl selenide, respectively, together with some dienes. " Quantitative studies of the acid- and base-catalysed hydrolyses of ethyl selenophen-2-carboxylate, of the reactions of selenophen-2-sulphonyl chloride and of 2-(chloromethyI)selenophen with aniline, and of selenophen-2-carboxaldehyde with aniline and with a phosphorus ylide have been carried out. The results were rationalized by correlation analyses with polar or electrophilic constants of heterocycles, depending on the electron demand of the side-chain. ""... 

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