The molecular mass of an unknown compound was found by mass spec to be 114. It h

Question

The molecular mass of an unknown compound was found by mass spec to be 114. It had a strong peak in its IR spectrum at 1710 cm^-1 There were 5 singlets in its^13C-NMR one of which was way downfield at 200 ppm. Other than oxygen (atomic mass 16), combustion analysis indicated that the rest of the compound consisted of only carbons and hydrogens. Proton-NMR data revealed 3 sets of hydrogens Indicate which hydrogens are Sets A, B & C in your structure. What is the molecular formula for this unknown? Write the structural formula for the compound, identifying each proton set in your structure. Set A: 1.00 ppm, singlet (9H) Set B: 2.10 ppm, singlet (3H) Set C: 2.30 ppm, singlet (2H) Write the structure for the following compound with molecular formula C_8H_9Br has the proton-NMR data listed below. Be sure to indicate which hydrogens are Set A, Set B and Set C in your structure. Set A: 2.00 ppm, doublet (3H) Set B: 5.15 ppm, quartet (1H) Set C: 7.29 ppm, multiple (5H)

Explanation / Answer

(1)

IR : 1710 cm-1 for C=O stretch

13C NMR : downfield peak below 200 ppm for C=O carbon

1H NMR

set A : 1.0 ppm, singlet, 9H for tert-butyl group

set B : 2.10 ppm, singlet, 3H for CH3 next to C=O

set C : 2.30 ppm, singlet, 2H for CH2 between C=O and tert-butyl group

a. Molecular formula = C7H14O

b. Structure

(CH3)3C-CH2-CO-CH3

(2) formula = C8H9Br

degree of unsaturation = 4

1H NMR

set A : 2.0 ppm, doublet, 2H for CH2 between Ph and CH

set B : 5.15 ppm, quartet, 1H for CH between CH2, CH3 and Br

set C : 7.29 ppm, multiplet, 5H for Ph protons

Structure

C6H5-CH2-CH(Br)-CH3

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.