Problem 9

Compound A, a solid, C₉H₈O₂ effervesces when added to a solution of sodium hydrogen carbonate (bicarbonate). It reacts immediately with bromine water, decolourising it, with the product being B, C₉H₈O₂Br₂. With aqueous sodium hydroxide solution B gives the sodium salt of C, C₉H₁₀O₄; this compound can be oxidised by acidified potassium dichromate solution to D C₉H₆O₄. D reacts with 2,4-dinitrophenylhydrazine but not with ammoniacal silver nitrate solution. D gives steamy fumes with phosphorus pentachloride, the organic product being E, C₉H₅O₃Cl.

With ammonia E gives F, C₉H₇O₃N.

Both G and A are oxidised by hot aqueous potassium manganate(VII) solution to the sodium salt of G, C₇H₆O₂.

Identify compounds A to G, explaining all the observations as fully as possible.

The MS, IR and NMR spectra of A are given below; make what deductions you can from these spectra.

Mass spectrum:

Infrared spectrum: Nujol mull. The Nujol mullis a technique where a solid is ground tp a paste with Nujol, which is a paraffin oil. The spectrum of Nujol is superimposed on the spectrum of the compound.

^{Proton NMR spectrum: (this is not required in the current Edexcel syllabus).}