1-Bromopropane, carbon-13 chemical

In chemical shift calculations for acylium ions, it was not necessary to model the ionic lattice to obtain accurate values. These ions have tetravalent carbons with no formally empty orbitals, as verified by natural bond orbital calculations (89). Shift calculations for simple carbenium ions with formally empty orbitals may require treatment of the medium. We prepared the isopropyl cation by the adsorption of 2-bromopropane-2-13C onto frozen SbF5 at 223 K and obtained a 13C CP/MAS spectrum at 83 K (53). Analysis of the spinning sidebands yielded experimental values of = 497 ppm, 822 = 385 ppm, and (%3 = 77 ppm. The isotropic 13C shift, 320 ppm, is within 1 ppm of the value in magic acid solution (17). Other NMR evidence includes dipolar dephasing experiments and observation at higher temperature of a scalar doublet ( c-h = 165 Hz) for the cation center. 

Experimentally, the isopropyl cation was prepared by the low temperature reaction of 2-bromopropane-2-13C with frozen SbF5. The 13C spectrum was measured at 83 K using slow speed magic angle spinning. Analysis of the spectrum using the method of Herzfeld and Berger yielded tensor values of 8n = 497 ppm, 822 = 385 ppm and 833 = 77 ppm for the central carbon, which results in an isotropic chemical shift of 320 ppm. 

Some chemical exposures and employment in some occupations where chemicals are used are known to impact fertility in women. These include exposures to lead, manganese, organic mercury compounds, carbon disulfide, 2-bromopropane, and welding fumes. 10 ... 

Protons in the same environment are called chemically equivalent protons. For example, 1-bromopropane has three different sets of chemically equivalent protons. The toee methyl protons are chemically equivalent because of rotation about the C—C bond. The two methylene protons on the middle carbon are chemically equivalent, and the two methylene protons on the carbon bonded to the bromine atom make up the third set of chemically equivalent protons. 

Bromopropane has two sets of chemically equivalent protons and, therefore, it has two signals in its NMR spectrum. The six methyl protons in 2-bromo-propane are equivalent, so they give rise to only one signal. Ethyl methyl ether has three sets of chemically equivalent protons the methyl protons on the carbon adjacent to the oxygen, the methylene protons on the carbon adjacent to the oxygen. 

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