Mike+Iannuzzi's+HNMR+Analysis+of+1,1-Dichloroethane

Name: Mike Iannuzzi Chemical: 1,1-Dichloroethane URL: []

Figure 1: H-NMR Spectrum of 1,1-dichloroethane Above is the H-NMR spectrum for 1,1-dichloroethane. This spectrum is showing two signals: one around 2 ppm and one around 6 ppm. These two signals exists due to the fact that 1,1-dichloroethane contains two types of hydrogen atoms. There also exists a signal at zero ppm which indicates that the scale is in ppm relative to o tetramethylsilane (TMS), and that it is defined as zero ppm.

Figure 2: Zoomed view of doublet signal for 1,1-dichloroethane



The first signal is a doublet that exists around 2.1 ppm. This doublet corresponds to the single hydrogen attached to the carbon with the two chlorine atoms. According to the “N+1” rule, a doublet will occur because there is only one hydrogen in a vicinal position with respect to our target hydrogen atoms. We know that this is indeed a doublet because the peaks are of same magnitude, fitting the 1:1 intensity ratio for a doublet. Furthermore, this signal occurs around 2.1 ppm because it corresponds to the methyl group, whose chemical shift is around 2.1 ppm when it is attached to a carbon with only one hydrogen atom.

Figure 3: Zoomed view of quartet signal for 1,1-dichloroethane

The other signal in this spectrum is a quartet that exists around 5.9 ppm. This quartet corresponds to the three hydrogen atoms attached to the carbon opposite the chlorine atoms (shown above). According to the “N+1” rule, a quartet will occur because there are three hydrogen atoms in a vicinal position with respect to our target hydrogen atom. Furthermore, this signal fits the 1:3:3:1 intensity ratio for a quartet. This signal occurs around 5.9 ppm, which fits the chemical shift for a single hydrogen atom attached to a carbon-carbon double bond. Even though there is no double bond, there still exists only one hydrogen atom because of the two chlorine atoms on the carbon, thus causing an alike chemical shift. If only one chlorine atom existed in this compound, creating chloroethane, the chemical shift would be around 3.3 ppm, fitting the 3-4 ppm range for a R-CH2-X chemical shift. Adding the second chlorine atom raises the chemical shift to the 5.9 ppm value shown above.