Polarity極性

• 依 Hard-Soft-Acid-Base theory(軟硬酸鹼理論,
  • hard particle is more polar and less polarizable.
  • soft particle is more polarizable and less polar.

依形成原理

• electronegativity(電負度差
• l.p
• 幾何形狀
• resonance產生

分類

• ionic comp'd
• permanent dipole
• instantaneously induced dipole: F原子因為electronegativity(電負度大所以不容易產生。 the ability to have instantaneously induced dipole is called polarizability(極化性，polarizability越大，表現得越有極性

形成作用力分類

依形成原理

strong chemical bond(化學鍵

ionic bond

weak chemical bond(化學鍵=intermolecular force

• ion-diple interaction
• permanent dipole-permanent dipole interaction Ex. H-bonding是此類中最強者.Van der Waals force
• permanent dipole-instantaneously induced dipole interaction Ex. Van der Waals force
• instantaneously induced dipole-instantaneously induced dipole interaction Ex. Van der Waals force

強弱分一+四類

strong chemical bond(化學鍵

ionic bond

weak chemical bond(化學鍵=Intermolecular force

• H-bonding是此類中最強者
• ion-diple interaction
• Van der Waals force(凡德瓦爾力=steric strain(立體張力(一種斥力)
  • Van der Waals force(凡德瓦爾力中之dipole-dipole interaction(偶極-偶極力)(permanent dipole-permanent dipole interaction)(Keesom force)
  • Van der Waals force中之permanent dipole-instantaneously induced dipole interaction(偶極-誘導偶極力)(Debye force)
  • Van der Waals force中之instantaneously induced dipole-instantaneously induced dipole interaction(誘導偶極-誘導偶極力)(London dispersion force)(London force(倫敦力)(dispersion force(分散力):分子量越大而越大

影響的性質

• bp
• mp
• Sy

例子

• alkane
• alkyl halide

延伸學習

IR

• 通常具有極性的分子才可以以IR分析

dielectric constant(介電常數ε

• 溶劑的極性以dielectric constant(介電常數ε表示,極性越大;介電常數越大:介電常數ε越大的溶劑越容易把正負電荷分開，常見的溶劑極性大小順序:H2O>甲醇>乙醇
• functional gr. polarity sequence
• organic comp'd ( originating from functional gr. ) intermolecular force sequence =b.p. sequence of organic comp'd
• 但是兩者有例外

like dissolves like(相似互溶原理

• 極性相似者容易互溶
  • 極性喜溶於極性 Ex. 溶於水者稱水溶性
  • 非極性喜溶於非極性 Ex. 溶於油者稱油溶性

酸鹼與極性

• 酸+鹼=鹽(酸鹼中和反應), 酸鹼和鹽相比較
  • 酸鹼的極性比較低
  • 鹽的極性比較高 Ex.鹽的水溶性比酸和鹼都要好

藥品動力學

• 極性小(像是酸鹼):如果是藥物則吸收好而且分布好 Ex.通常油溶性或是親油性
• 極性大(像是鹽):如果是藥物則吸收差而且分布差 Ex.通常水可溶或是親水性

Dye(染料

• Dye(染料 molecule上常具有sulfonate or carboxylate 以藉由dipole-dipole interaction(偶極-偶極力和 cartton or wool相黏
• Ex. Antimicrobial sulfas:prototype:prontosil→sulfanilamide

比較

Polarizability(極化性