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Química de los compuestos carbonílicos
el grupo carbonilo
Compounds that have only carbon and hydrogen atoms bonded to the carbonyl group
Compounds that contain an electronegative atom bonded to the carbonyl group
The presence or absence of a leaving group on the carbonyl carbon determines the type of reactions these compounds undergo.
el grupo carbonilo
Electrostatic potential map of formaldehyde, H2C=O
Ejemplos de aldehídos y cetonas
Pungent compounds found in capsicum, black pepper, and ginger
Aroma y sabor. Reacciones involucradas.
Generación de aromas y sabores via reacción de Maillard
Nomenclatura de aldehídos
Nomenclatura de cetonas
¿como se preparan los aldehídos y las cetonas?
REACCIONES DE ALDEHIDOS Y CETONAS
ReacFvidad del grupo carbonilo
Reac2vidades rela2vas de aldehídos y cetonas
Efectos electrónicos
efectos estéricos
trayectoria de Bürgi-‐Dunitz
LUMO
HOMO
HOMO highest occupied molecular orbital LUMO lowest unoccupied molecular orbital
HOMO
LUMO
Adición nucleoRlica bajo condiciones básicas
Adición nucleoRlica bajo condiciones ácidas
Nucleófilos
Nucleófilos de oxígeno
Hidratación catalizada por base
Hidratación catalizada por ácido
Formación de acetales
Catalizadores mas comunes
Mecanismo de la formación de acetales
Posición del equilibrio
Estabilidad de los acetales
• Carbonyls can be aYacked by alcohols to form hemiacetals.
– The intramolecular reacFon is generally favored for 5 and 6-‐ membered rings. WHY?
Cyclic Structures of Monosaccharides
• Monosaccharides, like glucose, can also undergo ring-‐closing hemiacetal formaFon.
• The equilibrium greatly favors the closed form called pyranose.
Cyclic Structures of Monosaccharides
Anomeric effect
• Which would you predict to be more stable?
9
– Beta 67% , alpha 33%, open 0.01%
• Ketoses form both furanose (5-‐membered) and pyranose (6-‐membered) rings:
Cyclic Structures of Monosaccharides
Cyclic Structures of Monosaccharides
• The equilibrium concentrations in water are above.
70% β 0.7% 23%-β 2% α 5%-α
¿de donde provienen los términos furanosa y piranosa?
O Opirano furano
• The furanose form takes part in most biochemical reacFons.
Cyclic Structures of Monosaccharides
• Disaccharides form when two sugars connect through a glycosidic linkage.
– The 1 à 4 glycosidic linkage is most common.
– The bottom ring is capable of mutarotaFon at its anomeric posiFon.
– Because the anomeric posiFon of the bottom ring is a HEMIACETAL rather than an acetal, it is in equilibrium with the open form. Thus, maltose is a reducing sugar.
Disaccharides
• Cellobiose is similar to maltose. WHAT are the differences?
• Will cellobiose be a reducing sugar?
Disaccharides
• Sucrose (table sugar) is also a disaccharide.
– Honey bees can convert sucrose into a mixture of sucrose, fructose, and glucose.
– Fructose is very sweet. • Sucrose is not a reducing sugar. WHY?
Disaccharides
• Cellulose is a polysaccharide containing 7000–12000 glucose units connected through glycosidic bonds.
• How is cellulose capable of giving plants like trees their rigidity and strength?
Polysaccharides
• Starch is a major components of grains and other foods, like potatoes. What is the difference between molecules of starch and molecules of cellulose? Starch is made of amylose and amylopecFn.
•
Polysaccharides
• Amylopectin has some 1à6-‐ α-‐glycoside branches.
Polysaccharides
We can eat corn and potatoes, but not grass or trees. WHY?
• Lactose is another disaccharide.
• Some people have trouble digesFng lactose.
Disaccharides
Nucleófilos de nitrógeno
Aminas primarias
imina
Mecanismo de la formación de iminas
Rapidez de formación de iminas en función del pH
Aminas secundarias