Succinic acid structure, properties, production, uses

The succinic acid is a solid organic compound whose chemical formula is C₄H₆OR₄. It is a dicarboxylic acid, that is, it has two carboxyl groups -COOH, one at each end of the molecule whose skeleton has 4 carbon atoms. It is also known as butanedioic acid. Said to be an alpha, omega-dicarboxylic acid, or a C4-dicarboxylic acid.

It is widely distributed in plants, fungi, and animals. Its succinate anion is an essential component within the Krebs cycle, which consists of a series of chemical reactions that occur during cellular respiration..

Succinic acid is one of the natural acids found in food, fruits such as grapes and apricots, vegetables such as broccoli and beets, cheeses and meats, among many others..

It is also found in yellow or succino amber, from which its name comes. It can be obtained by distillation of this or other resins. Industrially it is obtained by the hydrogenation of maleic acid.

Succinic acid is also generated during the fermentation of wine. In addition, it is a highly appreciated natural flavoring for various foods. It is also used as a raw material to obtain various chemical compounds that have applications in various industrial areas, medicine and cosmetics, among many others..

Article index

• 1 Structure
• 2 Nomenclature
• 3 Properties
  • 3.1 Physical state
  • 3.2 Molecular weight
  • 3.3 Melting point
  • 3.4 Boiling point
  • 3.5 Flash point
  • 3.6 Specific gravity
  • 3.7 Refractive index
  • 3.8 Solubility
  • 3.9 pH
  • 3.10 Dissociation constants
  • 3.11 Chemical properties
  • 3.12 Chemical reactions of industrial importance
• 4 Obtaining
• 5 Uses
  • 5.1 In the food industry
  • 5.2 In the wine industry
  • 5.3 In the production of other chemical compounds
  • 5.4 In various applications
• 6 References

Structure

Succinic acid has 4 carbon atoms linked in a linear but zigzag fashion. It is like a butane molecule in which the methyl groups -CH₃ are oxidized forming carboxylic groups -COOH.

Nomenclature

- Succinic acid

- Butanedioic acid

- 1,4-butanedioic acid

- 1,2-ethanedicarboxylic acid

- Amber acid

- Spirit of Amber

Properties

Physical state

Colorless to white crystalline solid, triclinic crystals or monoclinic prisms

Molecular weight

118.09 g / mol

Melting point

188.0 ºC

Boiling point

235 ºC

Flashpoint

160 ºC (open cup method).

Specific weight

1,572 at 25 ºC / 4 ºC

Refractive index

1,450

Solubility

In water: 83.2 g / L at 25 ºC.

Soluble in ethanol CH₃CH_twoOH, ethyl ether (CH₃CH_two)_twoOr, acetone CH₃Car₃ and methanol CH₃OH. Insoluble in toluene and benzene.

pH

A 0.1 molar (0.1 mol / L) aqueous solution has a pH of 2.7.

Dissociation constants

K₁ = 6.4 x 10^-5

K_two = 0.23 x 10^-5

Chemical properties

Dicarboxylic acids in general exhibit the same chemical behavior as monocarboxylic acids. However, the acid character of a dicarboxylic acid is greater than that of a monocarboxylic acid.

Regarding the ionization of its hydrogens, the ionization of the second carboxylic group occurs less easily than that of the first, as can be seen in the dissociation constants of succinic acid, where K₁ is greater than K_two.

Dissolves in aqueous NaOH and NaHCO₃ aqueous.

Succinic acid is not hygroscopic.

When heated, it very easily releases a water molecule and forms succinic anhydride..

Chemical reactions of industrial importance

By reduction reaction (the opposite of oxidation) succinic acid is converted to 1,4-butanediol.

By dehydrogenating 1,4-butanediol (elimination of hydrogen) γ-butyrolactone is obtained.

When 1,4-butanediol is cyclized (formation of a cyclic molecule), tetrahydrofuran is obtained.

By amination of succinic acid (addition of an amine) pyrrolidones are obtained.

Its polymerization with diols allows to obtain polyesters and with diamines polyamides are obtained. Both are widely used polymers.

Obtaining

The amount present in natural sources is very small, so it is industrially obtained by synthesis from other compounds generally derived from petroleum..

It can be produced by the catalytic hydrogenation of maleic acid or maleic anhydride.

Also from fumaric acid or starting from acetylene and formaldehyde.

However, all these are petrochemical processes polluting the environment and dependent on the price of oil. For these reasons, other production methods based on anaerobic fermentation have been developing for a long time, which are cheaper and less polluting..

These processes use CO_two, what is beneficial for the reduction of this gas and the greenhouse effect that it generates.

Its production can be fermentative for example with Anaerobiospirillum succiniproducens Y Actinobacillus succinogenes, that produce it in high concentrations from carbon sources, such as glucose, lactose, xylose, arabinose, cellobiose and other sugars. They also use CO_two as a carbon source.

There are researchers who promote the development of the concept of biorefineries, which would allow the full potential of renewable resources to be exploited. Such is the case of the use of effluents from the manufacture of paper, corn stalks, biomass from algae, sugarcane bagasse, cane molasses, waste from crop stems and beet pulp to obtain succinic acid, among other products. valuable.

For example, the use of beet pulp involves the extraction of pectin and the part rich in phenolic antioxidants, followed by hydrolysis of cellulose and hemicellulose to obtain fermentable sugars. The latter are the basis for obtaining succinic acid through its anaerobic fermentation in bioreactors..

Applications

In the food industry

Succinic acid naturally imparts flavor to food. It has a flavor-enhancing effect, so it is used as an additive in processed foods.

It has been suggested that it has effects on flavors that cannot be duplicated by other acids in foods, such as the so-called umami flavor in some cheeses (umami is a Japanese word that means "tasty").

It is even used in animal feed for its stimulation.

In the wine industry

Succinic acid occurs naturally during the alcoholic fermentation of wine. Of the non-volatile acids that are generated in this process, succinic acid corresponds to 90% of the total..

Wine contains approximately 0.5 to 1.5 g / L of succinic acid, which can reach 3 g / L.

In the production of other chemical compounds

Succinic acid is the raw material for obtaining products of high industrial value such as tetrahydrofuran, 1,4-butanediol, gamma-butyrolactone, adipic acid, linear aliphatic esters, N-methylpyrrolidone and biodegradable polymers..

These compounds and materials have numerous applications in the plastics industry (elastic fibers, elastic films), adhesives, industrial solvents (removal of paints and lacquers), cleaners in microelectronics, medicine (anesthetics, drug vehicles), agriculture, textiles and cosmetics..

In various applications

Succinic acid is an ingredient in some pharmaceutical preparations. Succinimides, derived from succinic acid, are used in medicine as anticonvulsants.

It is part of corrosion inhibitor formulas, serves as a plasticizer for polymers and is used in perfumery. It is also an intermediate in the synthesis of surfactants and detergents.

Succinic acid can be used as a monomer for the production of biodegradable polymers and plastics.

It is used in agricultural formulas for the growth of plantations.

Succinic acid salts are used in vehicle coolants and to promote de-icing, being less polluting than other compounds.

Succinate esters are used as additives in fuels.

References

1. U.S. National Library of Medicine. (2019). Succinic acid. Recovered from: pubchem.ncbi.nlm.nih.gov
2. Comuzzo, P. and Battistutta, F. (2019). Acidification and pH Control in Red Wines. In Red Wine Technology. Recovered from sciencedirect.com.
3. Alexandri, M. et al. (2019). Restructuring the conventional sugar beet industry into a novel biorefinery: Fractionation and bioconversion of sugar beet pulp into succinic acid and value-added co-products. ACS Sustainable Chemistry & Engineering. February 2019. Recovered from pubs.acs.org.
4. Methven, L. (2012). Natural food and beverage flavor enhancer. In Natural Food Additives, Ingredients and Flavors. Recovered from sciencedirect.com.
5. Featherstone, S. (2015). Ingredients used in the preparation of canned foods. In A Complete Course in Canning and Related Processes (Fourteenth Edition). Recovered from sciencedirect.com.
6. Qureshi, N. (2009). Beneficial biofilms: wastewater and other industrial applications. In Biofilms in the Food and Beverage Industries. Recovered from sciencedirect.com.