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Table 3 Attribution of diagnostic FTIR bands useful for detection of each DES [47-52]

From: Deep eutectic solvents: green solvents for the removal of degraded gelatin on cellulose nitrate cinematographic films

Wavenumber (cm−1)

Assignment

ChCl:EG

B:EG

B:U

 

1495

1491

νasH–C–H (CH3) in betaine

1479

1475

1472

δsC-H(31), δs CH2, δsCH3, δsCOH(48) and ρCH3(49) in choline chloride; νsCOO(47) and δaCH3 in betaine; νCN in urea

955

953 weak

955 weak

νaNC4, νC-C and νaCCO)in choline chloride; δC–C–N and v(CC)in betaine

933

933

δ C–N–C) and ρ(CH2) in betaine

883 medium

893

895 weak

ρC-H and ρCH2 in EG; νC–C and νs(CCN)) in betaine

  1. ν stretching, νs symmetrical stretching, νa asymmetrical stretching, δ bending, δs scissoring (for CH2) and symmetrical deformation (for CH3), δa asymmetrical deformation (for CH3), ρ rocking