Question

Mass Spectrometry (not shown: [M]-200 (50%) IM+2]- 202 (100%) M4]-204 (50%) m/z Infrared Spectroscopy (not shown): 2968, 2906 cm H Nuclear Magnetic Resonance. t 221 "C Nuclear Magnetic Resonance.

Answer 1

ANSWER: To propose a structure for an organic compound, an analysis of the following will help you. Like,

1. Analysis of mass spectrum data will gives information about the molecular weight and presence of any halogens in the compound.
2. Interpretation of IR data will provide the presence of possible functional groups.
3. NMR data will give information about the nature of hydrogens (1H-NMR) and carbons (13C-NMR) based on the appeared peaks and their position in the respective spectrums.

Below shown are the answers with brief explanations.

ANSWER: 1 Here I am proposing the structure first, then will explain the suggestions which forced me to propose the structure. (i.e.) 1,3-dibromopropane Brun Br 1 1 Br Br 1,3-dibromopropane As the Mass spectrum is showing the molecular ion peak [M+], [M+2] and [M+4]- peaks at m/2 200, 202 and 204 respectively in 1:2:1 relative ratio of abundance, we can conclude that the compound has two bromine atoms. The IR spectrum suggesting the follows: The absorption peaks around 2968 cm 1 and 2906 cm 1 suggesting the presence of only aliphatic hydrogens (-C-H stretching) in the compounds. Hence the compound is an alkane. The 1H-NMR spectrum interpretation was done and formulated in the table Multiplicity/No. Interpretation/possible fragment responsible of protons for the chemical shift Chemical shift (ppm) ~82.30 ppm (H2) Quintet/2H These protons are belonging to -CH2 protons which are present next to two -CH2 groups or one -CH & one-CH3 group. i.e. -CH2-CH2-CH2- or -CH-CH2-CH3 These protons may be belonging to 2*-CH2 groups present next to -CH2 group and also attached to a bromine atom. i.e.) 2* Br-CH2-CH2 Triplet/4H ~8 3.50 ppm (H1) 13C-NMR confirmed the presence of only two nonequivalent carbon atoms and which are as aliphatic carbons (peaks at 8 30.5, and 35 ppm). All these observations along with some literature verification, forced us to propose the above structure shown in the beginning.

ANSWER: 2) Here also I am proposing the structure first, then will explain the suggestions which forced me to propose the structure. (i.e.) dimethyl succinate 2 COOCH3 H3COOC dimethyl succinate As the Mass spectrum is showing the molecular ion peak [M] at m/z 146, we can conclude that the compound's molecular weight is 146 g/mol which doesn't have any chlorine or bromine atoms. And also, according to nitrogen rule, the compound might be with zero or even number of nitrogen atoms. The IR spectrum suggesting the follows: The absorption peaks around 2967 cm 1 suggesting the presence of only aliphatic hydrogens (-C-H stretching) in the compounds. Hence the compound is an alkane. The absorption peaks around 1739 cm 1 and 1164 cm-1 suggesting the presence of aliphatic ester group (-C=0 stretching vibrations &-C-O stretching vibrations) in the compound. The 1H-NMR spectrum interpretation was done and formulated in the table. The appearance of only singlets in the NMR spectrum suggesting that the compound is a symmetric compound, or it should have a plane of symmetry in it. Chemical shift Multiplicity/No. (ppm) of protons - 2.75 ppm singlet/4H (H2) Interpretation/possible fragment responsible for the chemical shift These protons are belonging to 2*-CH2 protons which are present next to each other as well as to a carbonyl group. (i.e.) 2*-CH2-CO- -8 3.70 ppm (H1) Singlet/6H These protons may be belonging to 2*-CH3 groups of an ester group. (i.e.) 2* -COO-CH2 13C-NMR confirmed the presence of three nonequivalent carbon atoms, as the spectrum showed three peaks at 8 173.0, 52.0 and 28.0 ppm. The peak appeared at 8 173.0 ppm should belongs to carbonyl carbon (-(C=0)0-] of an ester functional group. The peak appeared at 8 52.0 ppm should belongs to a carbon which is attached to an oxygen atom [- COO-C-] of an ester functional group. The peak appeared at 8 28.0 ppm should belongs to a carbon which is attached to a carbonyl group [- C-C=00-) of an ester functional group. All these observations along with some literature verification, forced us to propose the above structure shown in the beginning.