Cinnamic acid Chemical Properties
- Melting point:
- 133 °C(lit.)
- Boiling point:
- 300 °C(lit.)
- 2288 | CINNAMIC ACID
- refractive index
- 1.5049 (estimate)
- Flash point:
- >230 °F
- pK (25°) 4.46
- Water Solubility
- 511.2mg/L(25 ºC)
- JECFA Number
- Stable. Combustible. Incompatible with strong oxidizing agents.
- CAS DataBase Reference
- 621-82-9(CAS DataBase Reference)
- NIST Chemistry Reference
- 2-Propenoic acid, 3-phenyl-(621-82-9)
- EPA Substance Registry System
- Cinnamic acid (621-82-9)
Cinnamic acid Usage And Synthesis
Physical and Chemical Properties
Cinnamic acid, also known benzal acetate, 3-phenyl-2-propenoic acid, belongs to a kind of unsaturated aromatic acid with a slight smell of cinnamon. It is presented in balsam, cinnamon oil and coca leaf in the form of free or ester form. Owing to the presence of a double bond, cinnamic acid has trans-/ cis-two isomers with the cis form containing an extra three kinds of homogeneous polycrystalline. Both trans-form and cis-form are in the presence of nature. The trans-form exists in the presence of essential oils including storax, cinnamon oil, Peruvian balsam, basil oil and cocoa leaves. The cis-form exists in Malacca galangal oil with the trans-form being more stable than the cis-form. The commercially available products are mostly in the form of trans. It has a relative molecular mass of 148.17. The first crystalline form of the cis form is called allocinnamic acid with the compound precipitated from water being monoclinic. It is colorless to white prismatic crystals with the relative density being 1.284 (4 ℃), the melting point being 42 ℃, the boiling point 265 ℃ (decomposition ) and 125 ℃ (2.533 × 103Pa); it is slightly soluble in water (25 ℃ when 0.937) but easily soluble in alcohol, ether and ethyl acetate. The second polymorph is called alpha-iso-cinnamic acid with the compound precipitated from ligroin being the monoclinic crystal. It is colorless to white prismatic crystals with the mp being 58 ℃ and the boiling point being 265 ℃. It is soluble in ethanol, acetic acid, chloroform and acetone and easily soluble in ether. The third polymorph is called beta-iso-cinnamic acid; it appears as monoclinic colorless to white prismatic crystals with the mp being 68 ℃. It is soluble in alcohol, ether, acetic acid, chloroform and acetone. Trans-isomer precipitated from dilute ethanol belongs to the monoclinic crystal and appears as white to pale yellow prismatic crystals with the relative density being 1.2475 (4 ℃), melting point being 133 ℃ and the boiling point being 300 ℃. It is very slightly soluble in water (25 ℃: 0.1; 98 ℃: 0.588), soluble in ethanol (25 ℃: 23), chloroform (15 ℃: 5.9), easily soluble in benzene, ether, acetone, acetic acid and carbon disulfide. When being distilled at 140 ℃, it undergoes decarboxylation to become styrene (Styrax BP). Upon oxidation, it generates benzoic acid. Both the cis-and trans-isomers have flower honey aroma with sweet and spicy flavor. Rat-Oral LD50: 2500 mg/kg.
Role and purpose
Cinnamic acid is an important kind of organic synthetic raw material. It is mainly used for the synthesis of methyl cinnamate, ethyl cinnamate and cinnamic acid benzyl ester. It is widely used in the perfume industry and the pharmaceutical industry. In medicine, it has been ever used as an insect repellent.
Cinnamic acid was used as spices for the preparation of cherry, apricot, honey and cinnamon aromas and flavors; it can also be used as the starting material of cinnamic acid ester. The GB2760-1996 of our country provided that cinnamic acid is allowable edible spices; in addition, it can also be used as the raw material of photosensitive resin poly vinyl cinnamic acid series; it can also be used as the raw material for the synthesis of methyl, ethyl and benzyl esters. These esters, being used as fragrances, can be applied to cosmetics and soap, it can also be used as a local anesthetic, hemostatic agents and pharmaceuticals (lactic acid Prenylamine and baclofen, etc.) raw materials; cinnamic acid may also be used as plant growth regulators and raw materials of pesticides; anti-corrosion agents of fruit and vegetables; raw material of ultraviolet agent and photosensitive resin for cosmetic sunscreen. Cinnamic acid may also be used as the standard for organic trace analysis and determination of double bond, determination of uranium and vanadium and thorium separation.
Trans-cinnamic acid preparation method
1. it is extracted from the natural storax.
2. take benzaldehyde as raw material, in the presence of sodium acetate and pyridine; have it have Perkin aldol condensation reaction with acetic anhydride at 190~195 ℃; This will generate the crude product. After the recovery of acetic acid at atmospheric pressure, decolorize with charcoal, and then go through vacuum distillation, cooling and crystallization, recrystallization from ethanol, to obtain purified trans-cinnamic acid. In the above condensation reaction, the α-carbon from the acid anhydride can form bonds with the carbon in the carbonyl group of benzaldehyde, generating β-hydroxy acid anhydride. This intermediate product then further go through two steps including dehydration of acid anhydride and hydrolysis to derive this product.
3. Take dichlorotoluene as starting material; it is heated together with sodium acetate to 190 ℃ in the pyridine solution to give the crude product. After the recovery of acetic acid, go through refinement by recrystallization and then we can get the product of trans-cinnamic acid.
4. Take benzaldehyde and ethyl acetate as raw materials; have them be subject to condensation reaction (Claisen reaction) in the presence of sodium acetate to produce ethyl cinnamate, followed by hydrolysis to obtain the product.
5. Take benzaldehyde and acetone as raw materials; they are heated and subject to condensation reaction in alkaline medium to generate benzylidene acetone, and then use hypochlorite or sodium hypochlorite to oxidize the benzylideneacetone and can generate the crude product of cinnamic acid. After recycling the byproduct chloroform, further go through crystallization, washing and recrystallization to generate the final product.
6. Take benzaldehyde and acetyl chloride as raw materials, perform heating reaction to obtain the crude product. Go through concentration, salting, washing and recrystallization to obtain the refining product.
The above information is edited by the chemicalbook of Xiongfeng Dai.
Accurately weigh 500 mg of sample which have been previously dried for 3 hours in drier filled with silica gel; add 0.1mol/L hydrogen.
LD50 2500 mg/kg (rat, oral)
FEMA (mg/kg): Soft drinks 31; Cold drink 40; Confectionery 30; Bakery 36; Gum 10.
Take moderate as the limit (FDA§172.515, 2000).
It appears as white monoclinic prisms with slight cinnamon aroma. It is soluble in ethanol, methanol, petroleum ether and chloroform; it is easily soluble in benzene, ether, acetone, acetic acid, carbon disulfide and oils but insoluble in water.
1. It can be used as raw materials for the manufacturing of ester, spices and pharmaceuticals.
2. It can be used for chemical reagents as well as being used for the synthetic of perfume and pharmaceutical.
3. GB 2760-96 provides it for allowable edible flavors. It is mainly used for the preparation of spices and cherries, apricots, honey flavor. It can also applied to the anti-corrosion protection of fresh fruits and vegetables.
1. It can be obtained through the co-heating reaction between benzyl chloride and sodium acetate.
2. It can also be generated through the co-heating reaction between benzaldehyde and sodium acetate (or potassium acetate) in the presence of a dehydrogenating agent.
3. It can also be prepared through: mixing the benzoylacetone, sodium carbonate and bleach, generating sodium cinnamic acid, followed by processing with sulfate.
Cinnamic acid is a white crystalline organic acid, which is slightly soluble in water.
It is obtained from oil of cinnamon, or from balsams such as storax. It is also found in shea butter and is the best indication of its environmental history and post-extraction conditions. It can also be made synthetically.
Cinnamic acid is used in flavors, synthetic indigo, and certain pharmaceuticals, though its primary use is in the manufacturing of the methyl, ethyl, and benzyl esters for the perfume industry. Cinnamic acid has a honey- like odor; it and its more volatile ethyl ester (ethyl cinnamate) are flavor components in the essential oil of cinnamon, in which related cinnamaldehyde is the major constituent. Cinnamic acid is also part of the biosynthetic shikimate and phenyl propanoid pathways. Its biosynthesis is performed by action of the enzyme phenylalanine ammonia - lyase (PAL) on phenylalanine.
Cinnamic acid is freely soluble in benzene, diethyl ether, acetone, and it is insoluble in hexane.
Cinnamic acid is also a kind of self-inhibitor produced by fungal spore to prevent germination.
Cinnamic acid is almost odorless with a burning taste, and then turning sweet and reminiscent of apricot.
The trans- form has been found among the constituents of the essential oils of basil, Chinese cinnamon, Melaleuca bracteata, Alpinia galanga. It is reported found in Peru balsam, Asian and American storax and cocoa leaves. Also reported found in strawberry fruit, beer, cognac, starfruit (Averrhoa carambola L) and loquat. The cis- form is present in the oil of Alpinia malacensis.
Cinnamic Acid is a flavoring agent that consists of crystalline scales, white in color, with an odor resembling honey and flowers. it is slightly soluble in water, soluble in alcohol, chloroform, acetic acid, acetone, benzene, and most oils, and alkali salts soluble in water. it is obtained by chemical synthesis. it is also termed 3-phenylpro- penoic acid.
fragrance & flavoring agent, antidiabetic
cinnamic acid has sunscreen capabilities. Some manufacturers use it to replace PABA because of its lower allergic and phototoxic reaction incidence. Cinnamic acid is found in cinnamon leaves and cocoa leaves, and is an essential oil of certain mushrooms. It may cause allergic skin rashes.
ChEBI: A monocarboxylic acid that consists of acrylic acid bearing a phenyl substituent at the 3-position. It is found in Cinnamomum cassia.
Two isomers, trans- and cis- exist; the trans-isomer is of interest for use in flavoring; in addition to the extraction from natural sources (storax), it can be prepared as follows: (1) from benzaldehyde, anhydrous sodium acetate and acetic anhydride in the presence of pyridine (Perkin reaction); (2) from benzaldehyde and ethyl acetate (Claisen condensation); (3) from benzaldehyde and acetylene chloride; (4) by oxidation of benzylidene acetone with sodium hypochlorite.
Poison by intravenous and intraperitoneal routes. Moderately toxic by ingestion. A skin irritant. Combustible liquid. When heated to decomposition it emits acrid smoke and fumes.
Rainer Ludwig Claisen (1851–1930), German chemist, described for the first time in 1890 the synthesis of cinnamates by reacting aromatic aldehydes with esters. The reaction is known as the Claisen condensation.
Crystallise the acid from *benzene, CCl4, hot water, water/EtOH (3:1), or 20% aqueous EtOH. Dry it at 60o in vacuo. It is steam volatile. [Beilstein 9 IV 2002.]
- Benzoic acid
- Hyaluronic acid
- Citric acid
- Ethyl 2-(Chlorosulfonyl)acetate
- Cinnamon oil
- 3-Phenylpropionic acid
- Methacrylic acid
- Butyl acrylate
- Poly(acrylic acid)
- Ethyl acrylate
- Methyl acrylate
- 4-Methoxycinnamic acid
- Ascoric Acid
- Cinnamic acid
- Methyl methacrylate
- Methyl ester of Cinnamic acid
Cinnamic acid SupplierMore