CHAPTER 23 LIPIDS 23.1 INTRODCTION Lipids are compounds of biological origin that dissolve in pl nonopoler solvents Lipids are defined by the physical operation that we use to isolate them
CHAPTER 23 LIPIDS 23.1 INTRODCTION Lipids are compounds of biological origin that dissolve in nonopoler solvents. Lipids are defined by the physical operation that we use to isolate them
Lipids include a variety of structure types, For example H2C-O-C-R CH3 CH2OH HC-O-C-R O CH3 HC-0-C-R CH(CH3h A fat or oil Menthol Vitamin a (油或脂) (薄荷醇) (维生素A) H,C-0-C-R HRCI H HC-0-C—R CH, H H2C-O-P-OCH2CH2N+ CH3)3 lecithin Cholesterol (卵磷脂) (胆固醇
Lipids include a variety of structure types, For example H2C HC H2C O C R O C R' O C R'' O O O CH3 OH CH(CH3 ) 2 CH2OH CH3 CH3 CH3 CH3 A fat or oil (油或脂） Menthol (薄荷醇) Vitamin A (维生素 A） H2 C HC H2 C O C R O C R' O P OCH2 CH2N+( CH3 ) 3 O O O O - H H H 3 C H3 C H H H HO CH3 Cholesterol (胆固醇) lecithin (卵磷脂)
23.2 FATTYACIDS AND TRIACYLGLYCEROLS Triacylglycerols are the fats and oils of plant or animal origin. Oils: Triacylglycerols that are liquids at room temperature Fats: Triacylglycerols that are solids at room temperature Same triacylglycerols: all three acyl groups in triacylglycerols are the same mixed triacylglycerols: the acyl groups in triacylglycerols are different Hydrolysis of a fat or oil produced a mixture of fatty acias
23.2 FATTY ACIDS AND TRIACYLGLYCEROLS Triacylglycerols are the fats and oils of plant or animal origin. Oils: Triacylglycerols that are liquids at room temperature. Fats: Triacylglycerols that are solids at room temperature. Same triacylglycerols: all three acyl groups in triacylglycerols are the same. mixed triacylglycerols: the acyl groups in triacylglycerols are different. Hydrolysis of a fat or oil produced a mixture of fatty acids
H2C=O-C一R HOC-OH RCOOH HC-0-C-R' (1)OH/H,O, heat HC-OH RCOOH (2)H3O H2C-O-C-R H2C-OH RCOOH A fat or oil Glycerol Fatty acids (油或脂) (丙三醇) (脂肪酸) Most of fatty acids have unbrached chains and they have an even number of carbon atoms The double bonds in unsaturated fatty acids are all cis and not conjugated. Many naturally occurring fatty acids contain two or three double bonds. Triple bond rarely occur in fatty acids Saturated fatty acids have relatively high points and unsaturated fatty acids have relatively low points
H2 C HC H2 C O C R O C R' O C R'' O O O A fat or oil (油或脂） H2 C HC H2 C OH OH OH + RCOOH R'COOH R''COOH (1) OH- / H2 O, heat (2) H3O + Glycerol ( 丙三醇) Fatty acids (脂肪酸） Most of fatty acids have unbrached chains and they have an even number of carbon atoms. The double bonds in unsaturated fatty acids are all cis and not conjugated. Many naturally occurring fatty acids contain two or three double bonds. Triple bond rarely occur in fatty acids. Saturated fatty acids have relatively high points and unsaturated fatty acids have relatively low points
Triacylglycerols made up of large saturated fatty acids have high melting points and are solid in room temperature, vice versa 23.2A HYDROGENATION OF TRIACYLGLYCEROLS Solid commercial cooking fats are manufactured by partial hydrogenation of vegetable oils. Completed hydrogenation of the oil is very hard and brittle One commercial advantage of partial hydrogenation is to give the fat a longer shelf-life 23.2B BIOLOGICAL FUNCTION OF TRIACYLGLYCEROLS The primary function of triacylglycerols in animal is as an energy reserve
Triacylglycerols made up of large saturated fatty acids have high melting points and are solid in room temperature, vice versa. 23.2A HYDROGENATION OF TRIACYLGLYCEROLS Solid commercial cooking fats are manufactured by partial hydrogenation of vegetable oils. Completed hydrogenation of the oil is very hard and brittle. One commercial advantage of partial hydrogenation is to give the fat a longer shelf-life. 23.2B BIOLOGICAL FUNCTION OF TRIACYLGLYCEROLS The primary function of triacylglycerols in animal is as an energy reserve
unsaturated ones, can be synthesized from carbohydrates and c All of the saturated triacylglycerols of the body, and some of th proteins 23.2C SAPONIFICATION OF TRIACYLGLYCEROLS Alkaline hydrolysis of triacylglcerols produces glycerol and a mixture of salts of long-chain carboxylic acids H2C-OH RCOO- Na H2C-O-C-R H,O t naoh HC-OH t RCOO Na HC-0-C—R HOC-OH R"COO Nat H,C-0-C-R Glycerol Sodium carboxylates (丙三醇) (羧酸钠盐)
All of the saturated triacylglycerols of the body, and some of the unsaturated ones, can be synthesized from carbohydrates and proteins. 23.2C SAPONIFICATION OF TRIACYLGLYCEROLS Alkaline hydrolysis of triacylglcerols produces glycerol and a mixture of salts of long-chain carboxylic acids. H2 C HC H2 C O C R O C R' O C R'' O O O H2 C HC H2 C OH OH OH + RCOO - Na + R'COO - Na + R''COO - Na + Glycerol ( 丙三醇) Sodium carboxylates (羧酸钠盐） + 3NaOH H2 O
These salts of long-chain carboxylic acids are soaps and this saponification reaction is the way most soaps are manufactured Soaps are almost completely miscible with water. Soaps micelles in water are usually spherical clusters of carboxylate ions that are dispersed throughout the aqueous phase with their negatively charged carboxylate groups at the surface and with their nonpolar hydrocarbon chains on the interior Thus soap solution are able to separate the dirt particles because their hydrocarbon chains can"dissolve in the oil layer Synthetic detergents function in the same way as soaps; they have long nonpolar alkane chains with polar groups at the end
These salts of long-chain carboxylic acids are soaps and this saponification reaction is the way most soaps are manufactured. Soaps are almost completely miscible with water. Soaps micelles in water are usually spherical clusters of carboxylate ions that are dispersed throughout the aqueous phase with their negatively charged carboxylate groups at the surface and with their nonpolar hydrocarbon chains on the interior. Thus soap solution are able to separate the dirt particles because their hydrocarbon chains can “dissolve” in the oil layer. Synthetic detergents function in the same way as soaps; they have long nonpolar alkane chains with polar groups at the end
CH3(CH2),CH2S0,0 Na* CH3(CH2)nCH2OSO20Na Sodium alkanesulonates Sodium alkyl sulfates (烷基磺酸钠盐 (烷基硫酸钠盐) CH Na oo,s CH(CH2)nCHyCH3 Sodium alkylbenzenesulfonates (烷基苯磺酸钠盐) Synthesis of detergents offer an advantage over soaps; the ley function well in "hard water 23.2D REACTIONS OF THE CARBOXYL GROUP OF FATTYACIDS
CH3 (CH2 ) n CH2 SO2 O - Na + CH3 (CH2 ) n CH2 OSO2 O - Na + CH(CH2 )nCH2 CH3 + Na - OO2 S CH3 Sodium alkylbenzenesulfonates (烷 基 苯 磺 酸 钠 盐 ） Sodium alkyl sulfates (烷 基 硫 酸 钠 盐 ） Sodium alkanesulonates (烷 基 磺 酸 钠 盐 ） Synthesis of detergents offer an advantage over soaps; they function well in “hard” water. 23.2D REACTIONS OF THE CARBOXYL GROUP OF FATTY ACIDS
Fatty acids undergo reactions typical of carboxylic acids. they react with lialh4 to form alcohols. with alcohols and mineral acid to form esters, with thionyl chloride to form acyl chlorides (I)LiAIH4, diethyl ether RCHCHOH (2)H2O RCH,COOH RCH2 COOCH3 SOCI Pyridine RCHOCOCI 232E REACTIONS OF THE ALKYL CHAIN OF SATURATED FATTY ACIDS Fatty acids undergo specific halogenation when they are treated with bromine or chlorine in the presence of phosphorus
Fatty acids undergo reactions typical of carboxylic acids.they react with LiAlH4 to form alcohols, with alcohols and mineral acid to form esters, with thionyl chloride to form acyl chlorides: RCH2COOH (1)LiAlH4 , diethyl ether (2) H2O CH3OH, H + SOCl2 Pyridine RCH2 CH2OH RCH2 COOCH3 RCH2COCl 23.2E REACTIONS OF THE ALKYL CHAIN OF SATURATED FATTY ACIDS Fatty acids undergo specific halogenation when they are treated with bromine or chlorine in the presence of phosphorus
RCH COOH *(1)X2, P4 RCHXCOOH HX (2)H2O 232F REACTIONS OF THE ALKENYL CHAIN OF UNSATURATED FATTY The double bonds of the carbon chains of fatty acids undergo characteristic alkene addition reactions NB CH3(CH2)nCH2-CH2(CH2)mCO2H CH3(CH2),CH=CH(CH2)mCO2H CCl4 CH3(CH2), CHBrCHBr(CH2)mCO2H (2)NaHSos-CH3(CH2)nCHOH--CHOH(CH2)mCO2h HBrCH2(CH)CH2 CHBr(CH2)mCO2H CH3(CH2 ), CHBrCH2(CH2)mCO2H
RCH2COOH + (1) X2 , P4 (2) H2O RCHXCOOH + HX 23.2F REACTIONS OF THE ALKENYL CHAIN OF UNSATURATED FATTY The double bonds of the carbon chains of fatty acids undergo characteristic alkene addition reactions. CH3 (CH2 ) nCH=CH(CH2 )mCO2H H2 Ni Br2 CCl4 (1) OsO4 (2) NaHSO3 HBr CH3 (CH2 ) nCH2 CH2 (CH2 )mCO2H CH3 (CH2 ) nCHBrCHBr(CH2 )mCO2H CH3 (CH2 ) nCHOH CHOH(CH2 )mCO2H CH3 (CH2 ) nCH2CHBr(CH2 )mCO2H CH3 (CH2 ) nCHBrCH2 (CH2 )mCO2H +