Functional Group Analysis - Kannoukibunseki

Analysis of functional groups that indicate the characteristics of molecules. There are two types of chemical analysis: selective detection of functional groups by instrumental analysis such as infrared absorption spectroscopy, Raman spectroscopy, nuclear magnetic resonance, and polarography, and qualitative and quantitative analysis using chemical reactions specific to functional groups. The simplest and most common method is qualitative analysis by examining the presence or absence of characteristic absorption of functional groups from infrared spectra (infrared absorption spectra). For example, a large absorption near 1700 cm ^-1 indicates the presence of a carbonyl group, and carboxylic acids, esters, aldehydes, ketones, amides, etc. can be distinguished from each other based on the absorption wave number and the presence or absence of characteristic absorption of other functional groups. Quantitative analysis is performed based on the magnitude of absorbance of the characteristic absorption. In nuclear magnetic resonance, qualitative analysis can be performed by utilizing the fact that the chemical shift of ^1H or ^13C differs depending on the functional group to which the nucleus belongs. In polarography, functional groups are qualitatively identified by the half-wave potential, and quantified by the magnitude of the diffusion current. In chemical analysis, specific chemical reactions suitable for each functional group have been used for a long time, making selective qualitative and quantitative analysis possible. These include the Fehling's solution reduction of aldehydes, the silver mirror reaction, and the unsaturated bond quantification method using the addition of halogens to double bonds. To perform functional group analysis more accurately and to determine the bond positions of functional groups, it is effective to use instrumental analysis and chemical analysis together.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

分子の特性を表す官能基の分析．赤外吸収分光法，ラマン分光分析法，核磁気共鳴法，ポーラログラフィーなど機器分析により官能基を選択的に検出する方法と，官能基特有の化学反応を利用して定性，定量分析する化学分析がある．もっとも簡便で一般的な方法は，赤外スペクトル(赤外線吸収スペクトル)から官能基の特性吸収の有無を調べて定性分析することができる．たとえば，1700 cm^－1 付近の大きな吸収はカルボニル基の存在を示し，その吸収波数とほかの官能基の特性吸収の有無からカルボン酸，エステル，アルデヒド，ケトン，アミドなどを区別することができる．定量は特性吸収の吸光度の大きさによって求められる．また，核磁気共鳴法では，¹H または ¹³C の化学シフトがその核の属する官能基によって異なることを利用して定性ができる．ポーラログラフィーでは，半波電位によって官能基を定性し，拡散電流の大きさから定量する．化学分析法では，それぞれの官能基に適した特有の化学反応が古くから用いられてきており，選択的な定性・定量が可能である．アルデヒドのフェーリング液還元や銀鏡反応，二重結合へのハロゲンの付加を利用した不飽和結合定量法などがある．官能基分析をより正確に行うため，また官能基の結合位置を知るため，機器分析法と化学分析の併用が効果的である．

出典　森北出版「化学辞典（第2版）」化学辞典 第2版について　情報