(S)-(+)-アブシジン酸

化学的特性(+)-Abscisic acid (pure substance) is a colorless crystalline solid. It has a melting point of 160–161°C and sublimes at 120°C. The partition coefficients are 1.8 for the electrically neutral form and 0.94 for the ionic form. Its relative density is 1.21. The solubility in water is 3102 mg/L (at pH 4). The specific rotation is [α]²⁰D = +40.997° (c = 10.1 mg/mL in ethanol, at 20°C). The pKa is 4.61. It is soluble in chloroform, acetone, ethyl acetate, and diethyl ether but only sparingly soluble in benzene and water. The UV maximum absorption wavelength (in methanol) is 252 nm.

解説アブシジン酸，高等植物に広く存在する植物ホルモンの一種。成長を抑制する作用をもち，落葉や休眠，養分の蓄積を促進する。また，種子や冬芽の発芽を抑制する。気孔を閉じさせる作用もある。

用途アブシシン酸（アブシシンさん、アブシジン酸、英: abscisic acid、ABA）は、植物ホルモンの一種。構造的にはセスキテルペンに属する。休眠や生長抑制、気孔の閉鎖などを誘導する。また乾燥などのストレスに対応して合成されることから「ストレスホルモン」とも呼ばれる。

使用(+)-Abscisic acid is the natural isomer of the abscission-accelerating plant hormone and a plant growth regulator that exhibits multiple physiological effects, including inducing plant dormancy, inhibiting seed germination and plant growth, and stimulating stomatal closure.

合成方法(JOC, 1989, 54, 681)

純化方法Crystallise the acid from CCl4/pet ether, EtOH/hexane and sublime it at 120o. Also purify it by dissolving ~30g in 30mL of EtOAc, adding 100mL of hexane and allow to crystallise overnight (yield 8.4g), m 156-158o, 161-163o, [] D +426o (c 0.005M H2SO4 in MeOH). [Cornforth et al. Nature (London) 206 715 1965, Soukemp et al. Helv Chim Acta 72 361 1989.] The RS-isomer was purified on a Kieselgel F254 plate with toluene/EtOAc/AcOH (50:50:3) and has m 188-190o [Cornforth et al. Aust J Chem 45 179 1992]. [Beilstein 17/3 V 13.]