アクリル酸メチル-スチレン共重合体のモデル化合物のC=O伸縮振動

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The C=0 stretching frequency of some model compounds of methylacrylate (MA)-styrene (ST) copolymers in benzene was studied in order to explain the fact that the C=0 stretching band of MA units in MA-ST copolymers shifts to higher frequency as the MA content increases. The following results have been obtained. (1) The C=0 stretching band in methyl monocarboxylate, CH_3(CH_2)_nCOOCH_3 (2≦n≦8), occurs at the essentially constant frequency {(1740.5±0.3)cm^<-1>}. (2) The C=0 stretching band in dimethyl dicarboxylate, CH_3OOC(CH_2)_nCOOCH_3 (5≦n≦8), also occurs at the same frequency {(1740.5 ±0.3)cm^<-1>}, but when n≦4 the band shifts to higher frequency as n decreases. (3) The C=0 stretching band in CH_3OOC(CH_2)_nCOOCH_3 occurs at higher frequency compared with the band in CH_3(CH_2)_nCOOCH_3 or 〓-(CH_2)_nCOOCH_3 when n≦3. These results show that the C=0 band shifts to higher frequency due to intramolecular inductive effects of the carbonyl groups. Moreover, the noticeable results have also been obtained in other model compounds. (1) The C=0 stretching band of 2,4,6-tricarbomethoxyheptane, the model compound for MA-MA-MA triad, occurs at 1739.4cm^<-1> and that of polymethylacrylate at the essentially same frequency (1739.6 cm^<-1>). (2) The C=0 stretching band of 4-carbomethoxy-2,6-diphenylheptane, the model compound for ST-MA-ST triad, occurs at 1735.0 cm^<-1> and that of MA-ST alternating copolymer at just the same frequency (1735.0 cm^<-1>). In conclusion, the fact that the carbonyl stretching mode of MA units in MA-ST copolymers is sensitive to the sequence cnvironment and shifts to higher frequency as MA content increases can be reasonably explained by the intramolccular inductive effect of the carbonyl groups in the copolymers.
社団法人日本分析化学会の論文
1979-06-05

アクリル酸メチル-スチレン共重合体のモデル化合物のC=O伸縮振動

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