Question

Question 31 Which one of the following compounds is consistent with the following IR spectrum? 100 % Transmittance 1500 1000 SOO BODO Wavenumber(cm ) On OM III IV V OH

Answer 1

gives us The bands in T.R. spectroscopy following inpormation The broad peak between 3300- 3400 ant indicates the presence of Hydroxy group which was involvedin the Intermolecules Hydrogen bonding. If a broad peak is present between 2500 - 3000cmt then it may be due to -OH of carboxylic acid. But here no broad pe signal between 500 - 300 ml so toom this we can discard stoucture I → A peak at 31000ml indicater the stretching, opc-H opalkene. But some time this high value will be obsesved when c-H is adjacent to highly electronegative atoms like oxygen, chlorine, fluorine etc. To know whether it is alkene we should search in the region of 1600 - 165ount which gives the signal for c=c stretching →

2. A band between 16ooomil to and 17ooom! which that is is excast 165ocmit in the middle indicates the pop sonce opc =c. staetching so Therefore 3loocm & 16 socmit, these two indicate the presence op olepinic group in the compound. so compound IV contains bath - OH group and slopinic group. The given IR spe ctum belongs to compound TV 애 contain: keto group contains aldehyde soup But IR spectra is not showing peaks corresponding to czo stretching Eetween 100 asound 170ocht ) I contains only alcohol but bu IR spectro showing the prexente op c-c also some is not consect