Angelic acid
Encyclopedia
Angelic acid is a monocarboxylic
unsaturated organic acid
. It is mostly found in the plants of the family Apiaceae
. German pharmacist Ludwig Andreas Buchner
isolated angelic acid in 1842 from the roots of garden angelica (Angelica archangelica) which gave the acid its name. Angelic acid is a volatile solid with a biting taste and pungent sour odor. It is the trans isomer
of 2-methyl-2-butenoic acid, which easily converts to the cis isomer, tiglic acid
, upon heating or reaction with inorganic acids. The reverse transformation occurs much less readily. The salts and esters of angelic acid are called angelates. Angelic acid ester
s are the active components of herbal medicine used against a wide range of various health disturbances including pains, fever, gout
, heartburn, etc.
. These plants include Angelica archangelica, Peucedanum ostruthium (masterwort
), Levisticum officinale (lovage
), Euryangium Sumbul and Laserpitium latifolium
. In the latter plant, it is present in the resin called laserpicium
, and the oil of carrot also contains angelic acid. Sumbul plants might contain not angelic acid itself, but a larger complex which breaks into angelic acid upon processing. The acid can also be extracted from the oil of chamomile
flowers, and 85% of Roman chamomile (Anthemis nobilis
) oil consists of esters of angelic and tiglic acids; it also contains isobutyl angelate and amyl angelate. The acid content is highest in Angelica archangelica where it is about 0.3%.
or hot water and slowly in cold water. Angelic and tiglic acid
are trans and cis isomers of 2-methyl-2-butenoic acid, respectively. The former can be entirely converted to the latter by boiling for about 40 hours, by reaction with sulfuric
and other acids, by heating with a base to a temperature above 100 °C, or simply by storing the acid for about 25 years. The reverse transformation occurs much less readily; it can be induced by ultraviolet light, but not with visible light. The conversion rate is low and only 0.36 g of angelic acid could be obtained from 13 g of tiglic acid after 43-day irradiation with a 500-watt lamp. Despite being the trans isomer, angelic acid has a lower melting point and higher acid dissociation constant than tiglic acid, although the opposite trends are usually observed.
Angelic acid reacts with hydrobromic acid
and bromine producing bromovaleric
and dibromovaleric acids, respectively, with a yield of 60–70%. Chlorovaleric and iodovaleric acids are obtained using hydrochloric
and hydroiodic acids, respectively. The salts of angelic acid are called angelates. Angelates of alkaline earth metal
s M have a general formula M(C5H7O2)2 and form white, water-soluble crystals.
action of extracts from the plant butterbur. Roman chamomile
, in which esters of angelic and tiglic acids are the principal components, was used as a sedative
and tonic, and as a medicine against nervous problems, fever, colic, heartburn, loss of appetite, gout, headache and other health disturbances.
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
unsaturated organic acid
Organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are relatively stronger acids. The relative stability of the conjugate...
. It is mostly found in the plants of the family Apiaceae
Apiaceae
The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...
. German pharmacist Ludwig Andreas Buchner
Ludwig Andreas Buchner
Ludwig Andreas Buchner was a German pharmacologist.His father was Johann Andreas Buchner....
isolated angelic acid in 1842 from the roots of garden angelica (Angelica archangelica) which gave the acid its name. Angelic acid is a volatile solid with a biting taste and pungent sour odor. It is the trans isomer
Isomer
In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...
of 2-methyl-2-butenoic acid, which easily converts to the cis isomer, tiglic acid
Tiglic acid
Tiglic acid is a monocarboxylic unsaturated organic acid. It is found in croton oil and in several other natural products. It was also isolated from the defensive secretion of certain beetles.-Properties and uses:...
, upon heating or reaction with inorganic acids. The reverse transformation occurs much less readily. The salts and esters of angelic acid are called angelates. Angelic acid ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s are the active components of herbal medicine used against a wide range of various health disturbances including pains, fever, gout
Gout
Gout is a medical condition usually characterized by recurrent attacks of acute inflammatory arthritis—a red, tender, hot, swollen joint. The metatarsal-phalangeal joint at the base of the big toe is the most commonly affected . However, it may also present as tophi, kidney stones, or urate...
, heartburn, etc.
Name and discovery
Angelic acid was first isolated by the German pharmacist Ludwig Andreas Buchner (1813–1897) in 1842 from the roots of the garden plant angelica (Angelica archangelica) that gave the acid its name.Occurrence
Angelic acid occurs in the roots of many plants, especially of the family ApiaceaeApiaceae
The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...
. These plants include Angelica archangelica, Peucedanum ostruthium (masterwort
Masterwort
Masterwort typically refers to the plant Peucedanum ostruthium or Imperatoria ostruthium in the family Apiaceae, and not to be confused with great masterwort, Astrantia major, in the same family.-Use:...
), Levisticum officinale (lovage
Lovage
Lovage is a tall perennial plant, the sole species in the genus Levisticum, in the family Apiaceae, subfamily Apioideae, tribe Apieae.-Distribution:...
), Euryangium Sumbul and Laserpitium latifolium
Laserpitium latifolium
Laserpitium latifolium, common name Broad Leaved Sermountain is an herbaceous perennial plant in the genus Laserpitium belonging to the family Apiaceae.-Description:...
. In the latter plant, it is present in the resin called laserpicium
Silphium
Silphium was a plant that was used in classical antiquity as a rich seasoning and as a medicine. It was the essential item of trade from the ancient North African city of Cyrene, and was so critical to the Cyrenian economy that most of their coins bore a picture of the plant...
, and the oil of carrot also contains angelic acid. Sumbul plants might contain not angelic acid itself, but a larger complex which breaks into angelic acid upon processing. The acid can also be extracted from the oil of chamomile
Chamomile
Chamomile or camomile is a common name for several daisy-like plants of the family Asteraceae. These plants are best known for their ability to be made into an infusion which is commonly used to help with sleep and is often served with either honey or lemon. Because chamomile can cause uterine...
flowers, and 85% of Roman chamomile (Anthemis nobilis
Anthemis nobilis
Anthemis nobilis [synonym: chamaemelum nobile], commonly known as Roman camomile, chamomile, garden camomile, ground apple, low chamomile, English chamomile, or whig plant, is a low perennial plant found in dry fields and around gardens and cultivated grounds...
) oil consists of esters of angelic and tiglic acids; it also contains isobutyl angelate and amyl angelate. The acid content is highest in Angelica archangelica where it is about 0.3%.
Properties
Angelic acid is a volatile solid with a biting taste and pungent sour odor. It crystallizes in colorless monoclinic prisms which dissolve rapidly in alcoholAlcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
or hot water and slowly in cold water. Angelic and tiglic acid
Tiglic acid
Tiglic acid is a monocarboxylic unsaturated organic acid. It is found in croton oil and in several other natural products. It was also isolated from the defensive secretion of certain beetles.-Properties and uses:...
are trans and cis isomers of 2-methyl-2-butenoic acid, respectively. The former can be entirely converted to the latter by boiling for about 40 hours, by reaction with sulfuric
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
and other acids, by heating with a base to a temperature above 100 °C, or simply by storing the acid for about 25 years. The reverse transformation occurs much less readily; it can be induced by ultraviolet light, but not with visible light. The conversion rate is low and only 0.36 g of angelic acid could be obtained from 13 g of tiglic acid after 43-day irradiation with a 500-watt lamp. Despite being the trans isomer, angelic acid has a lower melting point and higher acid dissociation constant than tiglic acid, although the opposite trends are usually observed.
Angelic acid reacts with hydrobromic acid
Hydrobromic acid
Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C and contains 47.6% HBr by weight, which is 8.89 mol/L. Hydrobromic acid has a pKa of −9, making it a...
and bromine producing bromovaleric
Valeric acid
Valeric acid, or pentanoic acid, is a straight-chain alkyl carboxylic acid with the chemical formula C5H10O2. Like other low-molecular-weight carboxylic acids, it has a very unpleasant odor. It is found naturally in the perennial flowering plant valerian , from which it gets its name. Its...
and dibromovaleric acids, respectively, with a yield of 60–70%. Chlorovaleric and iodovaleric acids are obtained using hydrochloric
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
and hydroiodic acids, respectively. The salts of angelic acid are called angelates. Angelates of alkaline earth metal
Alkaline earth metal
The alkaline earth metals are a group in the periodic table. In the modern IUPAC nomenclature, the alkaline earth metals are called the group 2 elements. Previously, they were called the Group IIA elements . The alkaline earth metals contain beryllium , magnesium , calcium , strontium , barium and...
s M have a general formula M(C5H7O2)2 and form white, water-soluble crystals.
Applications
The angelic acid esters of sesquiterpene alcohols, such as petasin, are the active chemical behind the strong pain-relieving and spasmolyticMuscle relaxant
A muscle relaxant is a drug which affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeutic groups: neuromuscular blockers and spasmolytics...
action of extracts from the plant butterbur. Roman chamomile
Anthemis nobilis
Anthemis nobilis [synonym: chamaemelum nobile], commonly known as Roman camomile, chamomile, garden camomile, ground apple, low chamomile, English chamomile, or whig plant, is a low perennial plant found in dry fields and around gardens and cultivated grounds...
, in which esters of angelic and tiglic acids are the principal components, was used as a sedative
Sedative
A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....
and tonic, and as a medicine against nervous problems, fever, colic, heartburn, loss of appetite, gout, headache and other health disturbances.