1.6- Dioxaspiro nonane-2,7-dione

Succinic anhydride is dimerised to 1,6-dioxaspiro [4.4] nonane-2,7-dione by heating with sodium hydroxide. Modification of an existing procedure by adding further sodium hydroxide after the initial reaction led to a severe exothermic reaction after heating for some 30 h which fused the glass flask to the heating mantle, probably at a temperature approaching 550°C. The reason for this was not known [1], At elevated temperatures and under influence of alkali, succinic acid condenses decarboxylatively beyond the dimeric spiroacetal, sometimes explosively. Contamination of the anhydride with base is to be avoided [2],... 

Succinic anhydride is dimerised to 1,6-dioxaspiro [4.4] nonane-2,7-dione by heating with sodium hydroxide. Modification of an existing procedure by adding further... 

Di(4-hydroxyphenyl)-1,6-diazaspiro[4.4]nonane-2,7-dione is prepared from l,6-dioxaspiro[4.4]nonane-2,7-dione and p-aminophenol, and more basically by the reaction of p-aminophenol and 4-oxoheptanedioic acid. The reaction scheme is shown in Figure 8.4. 

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