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IR Flowchart to determine functional groups in a compound (all values in cm-1). All IR values are approximate and have a range of possibilities depending on the molecular environment in which the functional group resides. Resonance often modifies a peak's position because of electron delocalization (C=O lower, acyl C-O higher, etc.).
11 Φεβ 2023 · From there, a data table of approximate frequencies for different types of bonds has been created to use to help IR spectrum analysis. Table of Common IR Absorptions. Approximate Frequency (cm -1 )
Table of Characteristic IR Absorptions m=medium, w=weak, s=strong, n=narrow, b=broad, sh=sharp ... –1 bond functional group 3640–3610 (s, sh) O–H stretch, free hydroxyl alcohols, phenols 3500–3200 (s,b) O–H stretch, H–bonded alcohols, phenols 3400–3250 (m) N–H stretch 1˚, 2˚ amines, amides 3300–2500 (m) O–H stretch ...
The following table lists infrared spectroscopy absorptions by frequency regions.
For example, the most characteristic absorption band in the spectrum of 2-hexanone (Figure 6.3a) is that from the stretching vibration of carbonyl double bond C=O at 1716 cm-1. It is a very strong band compared to the others on the spectrum.
Infrared Spectroscopy (IR) – Triggering molecular vibrations through irradiation with infrared light. Provides mostly information about the presence or absence of certain functional groups. Mass spectrometry – Bombardment of the sample with electrons and detection of resulting molecular fragments.
Characteristic IR Absorption Peaks of Functional Groups* * Abbreviations: s = strong; m = medium; w = weak; br = broad; sat. = saturated; conj. = conjugated ** Alcohols, Esters, Carboxylic Acids, and Anhydrides also absorb in the fingerprint region due to the C-O stretch (1300 – 1000, s). Table 2.
