Dimethyl-1,3-dioxane-4,6-dione

A. 5-(1-Hydroxyethylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione. A flame-dried, 500-mL, three-necked, round-bottomed flask is equipped with a stir bar, nitrogen inlet adapter, and a pressure-equalizing addition funnel fitted with a rubber septum. The flask is charged with 22.0 g of Meldrum s acid dissolved in 153 mL of methylene chloride, and 24.8 mL of pyridine (Note 1), and the mixture is cooled to -25°C (Note 2). A mixture of 18.3 mL of methylene chloride and 13.1 mL of acetyl chloride is slowly added to the reaction mixture via the addition funnel over 1 hr (Note 3). After the addition of the acetyl chloride is complete, the reaction is slowly warmed over 3 hr to... 

Dimethyl-1,3-Dioxane-4,6-dione (Meldrum s Acid) Malonic acid, cyclic isopropylidene ester (8) 1,3-Dioxane-4,6-dione, 2,2-dimethyl- (9) (2033-24-1) Ethylenediammonium diacetate 1,2-Ethanediamine diacetate (9) (38734-69-9) (R)-Citronellal 6-Octenal, 3,7-dimethyl-, (R)-(+)- (8,9) (2385-77-5)... 

Dimethyl-1,3-dioxane-4,6-dione (Meldrum s acid) 0.72 g, 5.0 mmol may cause eye, skin, and respiratory tract irritation... 

MELDRUM S ACID 2,2-DIMETHYL-1,3-DIOXANE-4,6-DIONE MALONIC ACID, CYCLIC ISOPROPYLIDENE ESTER 1,3-DIOXANE-4,6-DIONE, 2,2-DIMETHYL- (2033-24-1), 67, 170 69, 33 p-Mentha-6,8-dien-2-one (6485-40-1), 66, 13... 

Dimethyl-1,3-dioxane-4,6-dione (Meldrum s acid) was purchased from Aldrich Chemical Co., Inc. and recrystallized before use according to the following procedure. Meldrum s aeid (10 g) was dissolved in a minimum amount of warm (40-45 °C) acetone (ca. 20 mL). Room temperature water (15 mL) was then added in one portion, resulting in the immediate precipitation of white needles which were collected by filtration on a Buchner funnel and dried (ca. 0.05 mm) in a desiccator over PjOj overnight. 

Dimethyl-1.3-dioxane-4,6-dione c/s-3,6-Dimethyl-1.4-dioxane-2,5-dione 2,2-Dimethyl-1,3-dioxolane-4-methanol... 

Dioxane is a colourless liquid, bp 105°C, readily soluble in all common solvents. It is prepared from formaldehyde and propane-1,3-diol in the presence of an acid catalyst. 2,2-Dimethyl-1,3-dioxane-4,6-dione 20 (Meldrum s acid) is obtained by cyclocondensation of acetone with malonic acid. Meldrum s acid represents a useful reagent in organic synthesis due to its reactivity as a malonate equivalent [131]. 

Anthracen-9-ylmethylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (4d) Solid, mp 193.6-194.3 °C reaction time 96 h ydeld 63% (NMR)... 

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