Question

LThe structure of a compound and its IR spectrum are given below List all the bond types in this molecule that you would expect to observe in the IR spectrum-include both stretches and bends. [6 pts Clearly label on the spectrum which peak corresponds to cach bond type. [6 pts 2 Circle the compound that best fits the IR spectrum for cach part. [3 pts each b) fracr CHe 1. The structure of a compound and its IR spectrum are given below H2C TIN-NIDA-3 3077 LIQUID FILN HAT-NO-1283 VINTL PROPIONATE EDBS-NU-1039 TSCONLO C eete 3499 3g94 760 CH CH CH3 CH 1272 esz 2947 1907 74 a) List all the bond types in this molecule that you would expect to observe in the IR spectrum include both stretches and bends. [6 pts b)Clearly label on the spectrum which peak corresponds to cach bond type. [6 pts] b) Clearly label on the spectrum which peak corresponds to each bond type. [6 pts] 2. Cirele the compound that best fits the IR spectrum for each part. [3 pts each] a) TER-NIDA-G3GO1LIQU1D FILH EDDS-NO-1032 n-XYLENE 29 691 CHa 221 24 67 424 4 H OH CH3 b) HIT-NO-040 18C0et DICTRTLRNNT HB085-N0-513 TH-NIDA-05034 FLIQUID FILN CHTH ese 127 77 CH CH CH CHa is27se 20 H OH H,CN CH3 H Bromination Lab age

Answer 1

Answer Question 1:

a) List of bond types that must appears in the IR spectrum of vinyl propionate:

• C-H stretch absorption for C sp² (at 3100-3000 cm^-1)
• C-H bend absorption for R-CH=CH₂ (at ~910 and ~900 cm^-1)
• C-H stretch absorption for C sp³ (at 3000-2800 cm^-1)
• C-H scissoring absorption (at ~1450 cm^-1)
• C-H rock for –CH₃ group (at ~1350 cm^-1)
• C=O stretch absorption for esters (at ~1735 cm^-1)
• C=C stretch absorption (at 1680-1640 cm^-1)
• C-O stretch absorption (at 1200-1000 cm^-1)

b) Bond types labeled in the IR spectrum of vinyl propionate:

HIT-NO 1282 SCORE SDBS-NO 1039 IR-NIDA-33077 LIOUID FILM VINYL PROPIONATE CsHp02 LOD b 50 C h g 500 1000 4000 3000 2000 HAVENUMBERI-1l

	Signal (cm-1)	Assignation
a	3100-3000	C-H stretch alkenes (=CH2 and =CH- groups)
b	3000-2800	C-H stretch alkanes (-CH3 and -CH2- groups)
c	~1750	C=O stretch esters
d	~1650	C=C stretch alkenes (-CH=CH2 group)
e	~1450	C-H scissoring absorption
f	~1350	C-H rock for –CH3 group
g	~1150	C-O stretch
h	1000-900	C-H bend alkenes (=CH2 and =CH- groups)

Answer Question 2:

a) The compound that bets fit with the IR spectrum is the compound A:

CH3 QH CH3 C B A

• All the expected signals for the compound A are observed in the spectrum:
  • C-H stretch for –CH³ groups (at 3000-2800 cm^-1)
  • C-H stretch for benzene ring (at 3100-3000 cm^-1)
  • C=C stretch for benzene ring (at ~1600 cm^-1)
  • Absorption for complex molecular movements for aromatic ring (at 1500-1400 cm^-1)
  • C-H rock for –CH₃ group (at ~1350 cm^-1)
• The compound B is discarded because the O-H stretch band (broad band centered at ~3300 cm^-1) is not observed in the spectrum.
• The compound C is discarded because the C=O stretch band (strong band at ~1710 cm^-1) and the C-O stretch band (strong band at ~1200 cm^-1) are not observed in the spectrum.

b) The compound that bets fit with the IR spectrum is the compound B:

H OH CH3 Hас. H C В

• All the expected signals for the compound B are observed in the spectrum:
  • N-H stretch for 2º amines (medium broad band centered at ~3300 cm^-1 with one fine peak)
  • C-H stretch for –CH³ groups (at 3000-2800 cm^-1)
  • C-H scissoring absorption (at ~1450 cm^-1)
  • C-H rock for –CH₃ group (at ~1350 cm^-1)
  • C-N stretch absorption (medium band at ~1200 cm^-1)
• The compound A is discarded because the following bands are not observed in the spectrum:
  • C=O stretch band (strong band at ~1710 cm^-1)
  • C-O stretch band (strong band at ~1200 cm^-1)
  • O-H stretch band for carboxylic acids (broad band centered at ~3000 cm^-1).
• The compound C is discarded because the typically alkine bands not observed in the spectrum:
  • C≡C stretch band (medium-weak band at ~2200-2100 cm^-1)
  • C-H stretch band for alkynes (narrow and strong band at ~3300 cm^-1)