324 PECTROSCOPY (c) The two ethyl groups of diethyl ether are equivalent to each other. The two methyl groups appear as one triplet and the two methylene groups as one quartet. CHCH,OCH,CH (d) The two ethyl groups of p-diethy benzene are equivalent to each other and give rise to a single triplet-quartet pa CHa CH2- -CHCH CH le) split either each other's signals or any of the signals of the ethyl grule ical shift and do not of the Four nonequivalent sets of protons occur in this compound CICH,CH,OCH,CH Vicinal protons in the CICH, CH,O group split one another's signals, as do those in the CH3CH,O group. 13.10 Both H, and H in m-nitrostyrene appear as doublets of doublets. H is coupled to Ha by a coupling constant of 12 Hz and to H by a coupling constant of 2 Hz. H is coupled to H, by a coupling con- stant of 16 Hz and to H, by a coupling constant of 2 Hz 12 HZ 16 hz 2 HZ 2 HZ 2 HZ (diagrams not to scale) 13.11 (b) The signal of the proton at C-2 is split into a quartet by the methyl protons, and each line of this quartet is split into a doublet by the aldehyde proton. It appears as a doublet of quartets (Note: It does not matter whether the splitting pattern is described as a doublet of quartets or a quartet of doublets. There is no substantive difference in the two descriptions. Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website(c) The two ethyl groups of diethyl ether are equivalent to each other. The two methyl groups appear as one triplet and the two methylene groups as one quartet. (d) The two ethyl groups of p-diethylbenzene are equivalent to each other and give rise to a single triplet–quartet pattern. All four protons of the aromatic ring are equivalent, have the same chemical shift, and do not split either each other’s signals or any of the signals of the ethyl group. (e) Four nonequivalent sets of protons occur in this compound: Vicinal protons in the ClCH2CH2O group split one another’s signals, as do those in the CH3CH2O group. 13.10 Both Hb and Hc in m-nitrostyrene appear as doublets of doublets. Hb is coupled to Ha by a coupling constant of 12 Hz and to Hc by a coupling constant of 2 Hz. Hc is coupled to Ha by a coupling con￾stant of 16 Hz and to Hb by a coupling constant of 2 Hz. 13.11 (b) The signal of the proton at C-2 is split into a quartet by the methyl protons, and each line of this quartet is split into a doublet by the aldehyde proton. It appears as a doublet of quartets. (Note: It does not matter whether the splitting pattern is described as a doublet of quartets or a quartet of doublets. There is no substantive difference in the two descriptions.) H3C Br C CH O This proton splits the signal for the proton at C-2 into a doublet. These three protons split the signal for proton at C-2 into a quartet. H O2N C C Ha Hb Hc Hb 2 Hz 2 Hz 12 Hz Hc 2 Hz 2 Hz 16 Hz (diagrams not to scale) ClCH2CH2OCH2CH3 Triplet Triplet Quartet Triplet H H H H CH3CH2 CH2CH3 Three signals: CH3 triplet; CH2 quartet; aromatic H singlet CH3CH2OCH2CH3 Quartet Quartet Triplet Triplet 324 SPECTROSCOPY Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website