Question

%T PerkinElmer Spectrum Version 10.4.4 Thursday, November 21, 2019 9:36 AM Analyst Administrator Date Thursday, November 21, 2019 9:36 AM 86 80 3646.74cm- 2042.99cm-1 70- 3455.51cm-1 CEC stretch 586.52cm-1 0-H Sttetch N-H sthet h 798 45em-1 P751 90cm-1 775 31cm-1 863.88cm-1 $33.95cm-1 60 Unkown 3 50 40 1421 97dm-1 30 131 h1PBabocm-1 | 2877.61cm-1 1462.97cmt 20 2937.87cm-1 1304.17em-11027.87cm-1 1371 74cm 095.39cm-1 10- 1256.17cm-1 2968.12cm-1 Spc-H stetcl 173 27cm-1 1185 90cm-1 0- 4000 2500 2000 550 3500 3000 1500 1000 cm-1 C=0 248 Sample 248 Date Thursday, November 21 2019 streteh Page 1

These are IR,1H,13C spectrums and the compound formula weight(FW) is 116.
How can I detetmine the structure of compound??
Help me!

Answer 1

Hi Dear Friend, the unknown identified as ethyl butyrate (IUPAC: ethyl butanoate)

IR:

2968 - 2877 cm-1, strong, sp3 C-H stretch

1736 cm-1, strong, ester C=O stretch

1462 - 1350 cm-1, medium multiple bands are due to sp3 C-H bending

1185.90 cm-1, strong, ester C-O stretch

Mass:

You say FW is 116, this is molecular ion m/z 116

please have a look at mass spectrum, you may find base peak (100% intensity peak) at m/z 43 & m/z 71 and other prominent peaks at m/z 29, 60 , 88

HNMR:

7.256 ppm, CDCl3 solvent peak

there are 5 signals

two triplets, 3H - characteristic of methyl protons in ethyl group -CH₂-CH₃

4.1 ppm, quartet, 2H & 1.25 ppm, triplet,3H - characteristic of ester ethyl group -CO-O-CH₂-CH₃

2.27 ppm, triplet, 2H ; 1.6 ppm, sextet, 2H; 0.96 ppm, triplet,3H due to -CH₂-CH₂-CH₃ fragment

CNMR:

173 ppm, characteristic of ester C=O carbon

77.00 ppm, triplet 1:1:1 intensity due to CDCl3 solvent peak

36 ppm, due to O-CH₂-

Unknown 3 Pulse Sequence spul Solventi cdc13 Ambient temperature Operator: ball File: 00261 Mercury-300BB wormhole OSO Relax delay 1.000 sec Pulse 45.0 degrees Acetime 1.958 sec Width 4800.8 Hz 8 repetitions OBSERVE HI. 300.0706244 MHZ DATA PROCESSING FT size 32768 Total time min. 25 sec WY 1221 801- 2.241 -2.291 8591 ZEST -7.259 4.155 _4.08 4 c d e TPP 2 1.45

Unknown 3 Pulse Sequence 52 pul Solventede 13 Ambient temperature Operator: Chem3 7 Om File: 0020 Mercury-300BB "wormhole 35.279 18.525 Relax delay 1.000 sec Pulse 45.0 degrees Acg time 1.301 sec Width 18115,9 HZ 64 repetitions OBSERVE CI3 75.452800 MHZ DE COUPLE H1 300.0720883 MHZ Power 38 dB continuously on WALT2-16 modulated DATA PROCESSING Line broadening 0.5 H2 FT size 55536 Total time 2 in 32 sec A 14.282 -13.674 -60.136 WyY -77.728 76.878 - 173.663 27.303 220 200 180 160 80 60 200 ppm

Hope this helped you!

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