REACTION OF MOLTEN SEBACIC ACID WITH A LAYERED (MG AL) DOUBLE HYDROXIDE/

Molten decane-1,10-dicarboxylic acid, sebacic acid, reacted with the l ayered double hydroxide (LDH) of initial composition 6Al3.4(OH)(18.82) (CO3)(1.51)(N0(3))(0.36)4.5H(2)O, at a temperature of 150 degrees C wh ich is ca. 24 degrees C above the melting point of the acid. The react ion was not strongly exothermic and hence may be controlled by a suita ble heating programme. X-Ray powder diffraction showed that the produc ts were polyphasic and microcrystalline materials, the compositions of which were related to the original molar ratios of acid:LDH. Typicall y, the dominant phases were unintercalated LDH up to an acid:LDH ratio of 0.75:1; intercalated dianion (ratio ca. 1:1); salt, e.g. magnesium sebacate (for ratios 4:1 and higher). Fourier-transform infrared (FTI R) and C-13 solid-state magic-angle spinning nuclear magnetic resonanc e (MAS NMR) spectroscopies of the reaction products confirmed the pres ence of the dianion (O2C)-O--(CH2)(8)CO2-. In no case was there eviden ce for undissociated guest acid molecules. The mechanism appears to in volve the sorption of the acid, initially at the crystallite edges, fo llowed by reaction of the molten acid with the basic solid host with e volution of CO2. The separated LDH layers then allow the acid to diffu se in. The product from the 1:1 mixture was similar to the intercalati on compound obtained using a modified version of Drezdzon's method, wh ich had previously been thought to be ineffective for sebacic acid.