甘油酯Gy cerides 1 Structure CH2-OH R-C—0H cH2-0-c-R1 cH—OH R1-C-OH cH—0→c-F R CH,OH Ri-C-OH CH2-o-C-R 3 glycerol fatty acids triacylglycerol or triglyceride a fat or an oil O R1R2=R3, simple triacylglycerol R,R23 are not same, mixed triacylglycerol Fat: solid and semisolid; oils; liquid
一、甘油酯 Glycerides 1. Structure CH2 CH CH2 OH OH OH R1 C OH O R1 C OH O R1 C OH O CH2 CH CH2 O O O C C C O O O R1 R2 R3 glycerol fatty acids triacylglycerol or triglyceride a fat or an oil z R1=R2=R3, simple triacylglycerol z R1, R2, R3 are not same, mixed triacylglycerol z Fat: solid and semisolid; Oils: liquid
甘油酯 Glycerides 2. Fatty acid o Carboxylic acids with long hydrocarbon chains o Saturared and unsaturated fatty acids C4-C24, even number of c, unbranched Double bond positions: C-9-C-10 Double bond configuration: Z o Melting point: Saturated> unsaturated o more double bond, lower melting point
一、甘油酯 Glycerides 2. Fatty acid z Carboxylic acids with long hydrocarbon chains. z Saturared and unsaturated fatty acids z C4~C24, even number of C, unbranched z Double bond positions: C-9 ~ C-10 z Double bond configuration: Z z Melting point: Saturated > unsaturated z more double bond, lower melting point
TABLE 24.1 Common Naturally Occurring Fatty Acids Number Common Systematic name Structure Melting of carbons name point Saturated lauric acid dodecanoic acid myristic acid tetradecanoic acid COOH 58 palmitic acid hexadecanoic acid COOH 63 stearic acid octadecanoic acid COOH 69 arachidic acid eicosanoic acid COOH 77 Unsaturated palmitoleic acid (9Z)-hexadecenoic acid COOH 0 18 oleic acid (9Z)-octadecenoic acid COOH linoleic acid (9Z, 12Z)-octadecadienoic acid COOH linolenic acid (9z, 12Z, 152)-octadecatrienoic acid COOH -l1 arachidonic acid (5Z, 8Z, 11Z, 14Z)-eicosatetraenoic acid COOH 50 EPA (5Z, 8Z, 11Z, 14Z, 17Z)-eicosapentaeneoic acid COOH -50
甘油酯 Glycerides 3. Properties 熔点的高低主要决定于脂肪酸的不饱和程度。 H2C-O-C 硬脂酸三甘酯 HC (mp72℃ H2C-0-CMMMMMMMY H2C-O-C O 油酸三甘酯 Hc-O-C (mp.-4℃) H2c-O
z 熔点的高低主要决定于脂肪酸的不饱和程度。 一、甘油酯 Glycerides 3. Properties H2C HC H2C O C O C O C O O O H2C HC H2C O C O C O C O O O 硬脂酸三甘酯 (mp.72℃) 油酸三甘酯 （mp.-4℃）
3. Properties ●甘油酯的变质一一酸败( rancidity) 不饱和脂肪酸的氧化所导致。 initiation RCH=CH--CH-CH=-+ X. RCH= CHeCH—CH=CH—+HX H resonance contributor with isolated double bonds RCH-CH=CH-CHCH resonance contributor with conjugated double bonds 算- propagation RCH--CH=CH—CH=CH O-0 radical RCH=CH—CH2-CH=CH propagation RCH=CHCH—CH=CH—+ RCH-c=CH—CH=CH一 an alkyl hydroperoxide
3. Properties z 甘油酯的变质 —— 酸败 (rancidity) —— 不饱和脂肪酸的氧化所导致