LACTONE
In chemistry, a lactone is a cyclic ester
which can be seen as the condensation
product of an alcohol group -OH
and a carboxylic acid
group -COOH in the same molecule. It is
characterized by a closed ring consisting
of two or more carbon atoms and a single oxygen atom, with a ketone group =O in one of the carbons adjacent to the other oxygen.
Synthesis
Many methods in ester
synthesis can also be applied to that of lactones. In one industrial synthesis
of oxandrolone the key lactone-forming step is an organic reduction - esterification
In halolactonization, an alkene is attacked by a halogen via electrophilic addition
with the cationic intermediate captured intramolecularly by an adjacent carboxylic acid (See also iodolactamization), for example in this
iodolactonization:
Specific methods
include Yamaguchi
esterification and nucleophilic
abstraction.
A recent study has
isolated β-lactones from bromination of 2,3-dimethylmaleate and/or
2,3-dimethylfumarate disodium salts, under ambient and aqueous conditions. The
carboxylate groups of the maleate and fumarate moieties exhibit neighbouring
group effects and alpha-lactones are proposed in the detailed mechanism
Reactions
The most stable
structure for lactones are the 5-membered γ-lactones and 6-membered δ-lactones
because, as in all organic cycles, 5 and 6 membered rings minimize the strain
of bond angles. γ-lactones are so stable that, in
the presence of dilute acids at room temperature, 4-hydroxy acids (R-CH(OH)-(CH2)2-COOH)
immediately undergo spontaneous esterification and cyclisation to the lactone.
β-lactones do exist, but can only be made by special methods. α-lactones can be
detected as transient species in mass spectrometry experiments.[6]
The reactions of
lactones are similar to those of esters, as exemplified by gamma-lactone in the
following sections:
Hydrolysis
Heating a lactone with a base (sodium hydroxide) will hydrolyse the lactone to its parent compound,
the straight chained bifunctional compound. Like straight-chained esters, the
hydrolysis-condensation reaction of lactones is a reversible reaction,
with an equilibrium.
However, the equilibrium constant
of the hydrolysis reaction of the lactone is lower than that of the straight-chained
ester i.e. the products (hydroxyacids) are less favored in the case of the
lactones. This is because although the enthalpies of the hydrolysis of esters and
lactones are about the same, the entropy of the hydrolysis of
lactones is less than the entropy of straight-chained esters. Straight-chained
esters give two products upon hydrolysis, making the entropy change more
favorable than in the case of lactones which give only a single product.
Reduction
Lactones can be reduced
to diols using lithium aluminium
hydride in dry ether. The reduction reaction will first break the
ester bond of the lactone, and then reduce the carboxylic acid group (-COOH) to
the alcohol group (-OH). For instance, gamma-lactones will be reduced to
butan-1,4-diol, (CH2(OH)-(CH2)2-CH2(OH).
Aminolysis
Lactones also react
with ethanolic ammonia, which will first break the ester bond and then react
with the acidic -COOH group, because of the basic properties of ammonia, to
form a difunctional group, i.e. alcohol and amide. Gamma-lactones will react to
yield CH2(OH)-(CH2)2-CO-NH2.
Michael reaction
Sesquiterpene lactones,
found in many plants, can react with other molecules via a Michael reaction.
http://en.wikipedia.org/wiki/Lactone
Examples
Artemisinin, a new, highly-effective anti-malarial compound, is a sesquiterpene lactone
found in Chinese wormwood. Lactucin, desoxylactucin,
lactucopicrin, lactucin-15-oxalate,
lactucopicrin-15-oxalate
are some of the most prominent found in lettuce and spinach, giving most of the bitter taste to
these crops.
One eudesmanolide,
3-oxo-5αH,8βH-eudesma-1,4(15),7(11)-trien-8,12-olide, can work with vernolic acid and other compounds in plants to
reduce inflammation
how to use lactone in the industry, and what products are in great need of lactone??
BalasHapusOne example of the use of the lactone in the industry
HapusAndrogaphidis meruakan paniculata extract of bitter herbs, flavonoid and laktone clinically very efficacious as a cure of diabetes mellitus.
Agaric Tea merupaan herbal products are highly efficacious as a treatment / maintanance people with diabetes mellitus as well as a health drink for everyone to increase endurance as a daily beverage.
Chemical content: Leaves and branches contain laktone consisting of deoksiandrografolid, Andrographolide (bitter substances), neoandrografolid, 14-deoxy-11-12-didehidroandrografolid, and homoandrografolid. There is also a flavonoid, alkane, ketone, aldehyde, minerals (potassium, calcium, sodium), grit acid, and resin. Flavotioid most isolated from the roots, namely polimetoksiflavon, andrografin, pan.ikulin, mono-0-metilwithin, and apigenin-7, 4 - dimetileter. Andrographolide active substance proved efficacious as hepatoprotektbr (protects liver cells from toxic substances).
http://maharanibernadetta.blogspot.com/2012/05/lakton.html
http://sitiraihan1993.blogspot.com/2012/05/lakton-lakon-adalah-sebuah-ester-siklik.html
GDL (Delta Glucose-lactone) in Food
Additives play a major role in making food. Delta-lactone glucose, also known as gluconolactone, or GDL for short, is a starch-based food additive made from corn. This serves several purposes in the food manufacturing industry. GDL is a compound D-Gluconic acid, derived from glucose through a process of fermentation. Gluconic acid occurs naturally in fruits, honey, plants and wine.
seasoning
One of the primary uses of the GDL in the diet is to give a sour taste, which is a class of food additives which serve the purpose of lowering the pH. This makes it more acidic foods, contributing to acid or bitter taste. In this way, it acts as a flavoring agent for foods and beverages. It is added to processed foods to contribute to sour taste. GDL is similar to citric acid, an acid taste better known and widely used.
preservative
Processed food is produced to last on the shelves of grocery stores for months at a time. Preservatives are added to prevent food from spoiling. GDL manufacturers add to food to preserve their shelf life by regulating the acidity. The effect of lowering the pH of the acid and make more food to prevent growth of microorganisms that would normally break down food.
Food Products
GDL was added to the shell where it acts as a stabilizer and contributes to the color. It is added to canned fish and processed meats like sausage as a preservative and flavoring. In salmon products, GDL is added to contribute to the flavor and color. GDL was added to a particular cheese to achieve a sharp flavor. In baked goods, baking GDL helps support the process and act as a preservative.
http://arghopoetra.blogspot.com/2012/05/lakton.html
In the article above we can summarize that lactone can be synteshized by esterification
BalasHapushalolactonization,iodolactonization, and nucleophilic abstraction. What about the differences about those methods. Mimii, could you give me the explanation about that ?