1) Give the molecular ion that would be observed in the mass spectrum of this co

Question

1) Give the molecular ion that would be observed in the mass spectrum of this compound and 2-3 key IR peaks that would help identify the molecule.

2) Show using curved arrows how this molecule would react with aqueous sodium ethoxide. Draw the stuctures and give the IUPAC name of each anticipated neutral organic product.

3) The initial molecule is reacted with DBU in a polar aprotic solvent, draw the structures of teh neutral organic products and provide the pertinent 1H NMR spectral details (Chemical shift, integration, and multiplicity) expected for product.

4) Taking a product from 3 above as theAgaian, starting material, sketch and give the IUPAC names for the neutral organic products of the reaction with BH3 THF, followed by oxidation using H2O2 and NaOH.

7) Starting with the product of 6, sketch and give the IUPAC names for the neutral organic products of the reaction with osmium tetroxide. Determine the mass of the molecular ion for this product and compare it with that of the starting material for this reaction.

Explanation / Answer

1) In a mass spectrum, the peak representing the molecular ion is called the molecular ion peak (symbol: M peak). Excluding any peaks due to the presence of heavier isotopes, the molecular ion peak is the peak with the highest mass-to-charge ratio.

For the given compound, the exact mass of the compound is is 218.07 ( because molecular formula is C10H19Br and i have calculated using the exat masses of the atoms).

Bromine has two isotopes, 79Br and 81Br in an approximately 1:1 ratio (50.5 : 49.5 exact). That means that a compound containing 1 bromine atom will have two peaks in the molecular ion region, depending on which bromine isotope the molecular ion contains.So, the two peaks will be very similar in height.

so molecular ion peaks M+ = 218.07

   M+2 = 220.06

IR peaks which could help identify this molecule are

C-Br stretch   690-515 cm-1

C-H stretch   2950 - 2850 cm-1

C-C stretch 1200 cm-1

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