Concept explainers
(a)
Interpretation:
The explanation for the fact that the
Concept introduction:
Spectroscopy method is used to identify the structure of the substance. The mass spectroscopy is used to determine the molecular mass of a compound. In the mass spectrum, the molecular ion peak is the most important peak. The ratio
(b)
Interpretation:
The explanation for the fact that the spectrum of
Concept introduction:
Spectroscopy method is used to identify the structure of the substance. The mass spectroscopy is used to determine the molecular mass of a compound. In the mass spectrum, the molecular ion peak is the most important peak. The ratio
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Organic Chemistry
- 20. (a) The UV spectrum of acetone shows two peaks at 15. 7-max = 280 nm max = 1900 nm Emax max and 100. (1) identify the electronic transition for each. (ii) which one of these is more intense ? (b) Why is methanol a good solvent for UV but not for IR determination? 21. (a) How will you detect C=C-C=Cby UV spectroscopy? (b) Write why absorption bands are formed in ultra-violet spectrum instead of sharp peaks ?arrow_forwardReaction of butanenitrile (CH3CH2CH2CN) with methylmagnesium bromide (CH3MgBr), followed by treatment with aqueous acid, forms compound G. G has a molecular ion in its mass spectrum at m/z = 86 and a base peak at m/z = 43. G exhibits a strong absorption in its IR spectrum at 1721 cm−1 and has the 1H NMR spectrum given below. What is the structure of G?arrow_forward(a) The 'H-NMR spectrum of cyclobutanone shows two signals - signal A at 3.00 ppm and signal B at 1.95 ppm. Give the multiplicity of each signal. cyclobutanone (b) When cyclobutanone is treated with D20 and NaOD, the only signal observable in the 1H-NMR is a singlet at 2.00 ppm. Explain why this is the case. [Note: Deuterium atoms do not display signals in the TH-NMR spectrum]arrow_forward
- 4. (a) Chemical shift (8) value of CH and CH3 proton in [Al(acac)3] are 1.99 and 5.47 ppm, respectively whereas in [Fe(acac)3] the 8 values of CH and CH3 proton are shifted to more downfield region i.e, 2.18 and 5.52 ppm, respectively where 'acac' denotes acetylacetonate anion. Explain the observation.arrow_forwardReaction of butanenitrile (CH3CH2CH2CN) with methylmagnesium bromide (CH3MgBr), followed by treatment with aqueous acid, forms compound G. G has a molecular ion in its mass spectrum at m/z = 86 and a base peak at m/z = 43. G exhibits a strong absorption in its IR spectrum at 1721 cm−1 and has the 1H NMR spectrum given below. What is the structure of G? We will learn about the details of this reaction in Chapter 22.arrow_forward2 (a) In the following reaction, OH РСС A (i) Draw the structure of compound A. (ii) Explain using the IR spectra to confirm that the reaction is completed. (iii) Identify the molecular ion peak for compound A. (iv) Fragmentation of A shows a peak at m/z 111. Draw the possible cation for this peak. (v) Determine the resonance structure of this cation.arrow_forward
- Compound b is a derivative of compound a. Comparing ¹H NMR of a and b, we found that two signals shown in compound a move to downfield around 7.38 ppm and 8.42 ppm in compound b. Identify the two protons that most likely give rise to these signals and justify your decision. (3 pts) (a) Ĵ (b)arrow_forwardHow could 1H NMR spectroscopy be used to distinguish among isomersA, B, and C?arrow_forwardTreatment of 2-methylpropanenitrile [(CH3)2CHCN] with CH3CH2CH2MgBr, followed by aqueous acid, affords compound V, which has molecular formula C7H14O. V has a strong absorption in its IR spectrum at 1713 cm−1, and gives the following 1H NMR data: 0.91 (triplet, 3 H), 1.09 (doublet, 6 H), 1.6 (multiplet, 2 H), 2.43 (triplet, 2 H), and 2.60 (septet, 1 H) ppm. What is the structure of V? We will learn about this reaction in Chapter 20.arrow_forward
- Butanal and methylpropanal give slightly different mass spectra. Both give a molecular ion peak at m/z = 72, but butanal gives four other peaks whereas methylpropanal only gives three. State the species responsible for the four other peaks in the mass spectrum of butanal and write equations to show their formation from the molecular ion.arrow_forwardKetones undergo a reduction when treated with sodium borohydride, NaBH4. What is the structure of the compound produced by reaction of 2-butanone with NaBH4 if it has an IR absorption at 3400 cm-1 and M+=74 in the mass spectrum?arrow_forwardMass spectra of butylcyclopentane and tert-butylcyclopentane were acquired. Spectrum A exhibited significant mass peaks at m/z values of 126, 97, 83, 69, 55, and 41. Spectrum B exhibited significant peaks at m/z values of 111, 69,57, and 41. Match each spectrum with its compound.arrow_forward