Characterization of Decomposition Residues

Sodium alkoxides on decomposition produce satxuated and imsaturated gaseous hydrocarbons with solid black powdery residue. Various techniques such as AES, CHNS, volumetric and gravimetric analysis, IR analysis and XRD were used to characterize the solid residue. 

Estimation of carbon, hydrogen and sodium content in residue About 10 mg of solid residues left after the decomposition of sodium alkoxides were loaded in tin crucibles of size 3.5x9.0x0.1 mm inside the argon atmosphere glove box and hermetically sealed by crimping as described in characterization on RONa. These crucibles were loaded in the CHNS elemental analyzer (M/s Elementar Vario EL, Germany) for measurement of carbon and hydrogen contents as explained previously. 

Stock solutions were made by dissolving about 100 mg samples from the decomposition residues of sodium alkoxides in dilute hydrochloric acid and distilled water. Necessary dilutions were made by taking aliquot from these stock solutions and used for sodium analysis using AES as explained previously. 

Confirmation test for carbonate radical In order to confirm the presence of carbonate in the decomposition residue of sodium alkoxides, the residues were taken in a suitable air tight glass vessel connected to a gas bubbler containing lime water. Addition of dilute hydrochloric acid to the decomposition residues of sodium alkoxides produced brisk effervescence indicating that the residue might contain carbonate. The evolved gas turned clear limewater solution to milky white, confirming that the residue contained sodium carbonate. 

Estimation ofNafCO and NaOH contents by volumetric method Volumetric titration method was resorted to estimate the quantity of sodium carbonate and sodium hydroxide to account for oxygen and the results are given in Table 15.5. About 100 mg of decomposition residue of sodium alkoxides were dissolved in distilled water and 

---