红外光谱法讲稿2.ppt

* Unknown #1 3100 -- The broad intense absorption band seen here is characteristic of a carboxylic acid dimer. 2960 -- CH aliphatic assymmetric stretch2870 -- CH aliphatic symmetic stretching vibrational band.1415 -- Absorption in this region is due to CH3. Note the weak band just below 1400. This is the methyl bending vibrational band.1290 -- Due to coupling of the in-plane OH bending and CO stretching of the dimer.950 -- OH out-of-plane bending of the dimer.The compound is octanoic acid * Unknown #3 3250 -- Hydrogen bonded OH.3120 -- Aromatic CH.2820 -- Aldehyde CH1690 -- C=O 1600 1500 -- Aromatic nucleus.1200 -- Phenol C-O absorption. The absorption for alcohols is primary, 1050, secondary, 1100 and tertiary at 1150.760 720 -- 4-adjacent hydrogens on an aromatic ring. Ortho substitution.The compound is salicylaldehyde, 2-hydroxybenzaldehyde. 分子式为C7H8O的红外光谱图 分子式为C8H7N的红外光谱图 * 分子式为C10H10O4的红外光谱图 * 某化合物的分子式为C5H8O，其红外光谱有如下主要吸收带:3020，2900，1690和1620cm—1；其紫外吸收光谱在λmax=227nm，εmax=104。已知该化合物不是醛，试指出它可能的结构。 Ω=2 1690 vC=O 可能有共轭效应 1620 vC=C ， 3020应为v=CH 2900 饱和vCH * * * * * * * * * * * * * * 22. Analysis: C8H8O * 23. Analysis: C3H10NO * 24. Analysis: C4H8O2 * 25. C8H16O2 * C7H6O2 * 某化合物的分子式C6H14，红外谱图如下，试推测该化合物的结构。 * 1420 =C-H面内弯曲 * C8H8O From the molecular formula, the compound has 5 degrees of unsaturation (five double bonds, carbonyls or rings). The large number suggests the possible presence of an aromatic ring (4 degrees of unsaturation). 3400-3200 cm-1: no OH or NH present. 3100 cm-1: moderate peak suggesting unsaturated CH. 2900 cm-1 weak peak indicating possible saturated CH. 2200 cm-1: no unsymmetrical triple bonds. 1690 cm-1: strong carbonyl absorbance. 1610 cm-1: weak absorbance bands consistent with carbon-carbon double bonds The spectrum seems to be consistent with a carbonyl compound containing both single and double bonds. The carbonyl absorbance occurs at a relatively low wave number