4-hydroxybenzoic acid

Structural formula
Crystal system	monoclinic prismatic
General
Surname	4-hydroxybenzoic acid
other names	PHBS, 4HBA, p-OHB; PHB; Parabens; p -hydroxybenzoic acid; para-hydroxybenzoic acid; p- salicylic acid; p -oxybenzoic acid; Catalpa acid (obsolete); 4-HYDROXYBENZOIC ACID ( INCI ) ;
Molecular formula	C 7 H 6 O 3
Brief description	colorless, odorless, flammable solid
External identifiers / databases
EC number	202-804-9
ECHA InfoCard	100.002.550
PubChem	135
ChemSpider	132
DrugBank	DB04242
Wikidata	Q229970
properties
Molar mass	138.12 g mol −1
Physical state	firmly
density	1.46 g cm −3
Melting point	213-215 ° C
boiling point	decomposition
pK s value	pK s 1 = 4.61; pK s 2 = 9.3;
solubility	Water: 4.9 g l −1 at 20 ° C, 335 g l −1 at 100 ° C; soluble in ethanol, ether and acetone; soluble in alkalis with salt formation;
safety instructions
H and P phrases	H: 318-335
	P: 280-305 + 351 + 338 + 310
Toxicological data	> 10000 mg kg −1 ( LD 50 , rat , oral ) ; 2200 mg kg −1 ( LD 50 , mouse , oral ) ; 932 mg l −1 ( EC 50 , crustaceans , 48 h , median value) ; 42.8 mg l −1 ( EC 50 , algae , 96 h ) ;
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

4-Hydroxybenzoic acid is a chemical compound belonging to the group of hydroxybenzoic acids . It is a breakdown product and intermediate in the metabolism of quinones in eukaryotes .

4-Hydroxybenzoic acid ( para -hydroxybenzoic acid ) was also previously known as catalpic acid because it is found in the leaves and fruits (pods) of the trumpet trees ( Catalpa spp.). The term catalpic acid is now used to refer to the fatty acid contained in larger quantities in the seed oil of species ( Catalpa spp. And others) of the trumpet tree family (Bignoniaceae) . p -hydroxybenzoic acid is the name to the substance group of parabens ( para -hydroxy ben benzoic acid).

presentation

4-Hydroxybenzoic acid is produced commercially from potassium phenate and carbon dioxide in a Kolbe-Schmitt reaction :

In the laboratory, the preparation takes place by heating potassium salicylate with potassium carbonate to 240 ° C, followed by treatment with acid ( hydrochloric acid ).

biosynthesis

4-Hydroxybenzoic acid arises from several substances: in plants from its adduct with coenzyme A , which in turn arises from 4-cumaroyl-CoA; in bacteria during the oxidation of benzoic acid ( EC 1.14.13.12 ) or during the breakdown of chorismic acid ( EC 4.1.3.40 ), 4-methoxybenzoic acid ( EC 1.14.99.15 ), 4-hydroxybenzaldehyde ( EC 1.2.1.64 ) or 4-chlorobenzoic acid ( EC 3.8.1.6 ). It can also be decarboxylated to phenol or oxidized to 3,4-dihydroxybenzoic acid. In the biosynthesis of the ubiquinones , it is linked to a polyprenyl radical.

properties

The aqueous solution of 4-hydroxybenzoic acid reacts acidic ( pH value : 3.3 at a measuring temperature of 20 ° C and a concentration of 1 g / l).

use

4-Hydroxybenzoic acid is mainly used technically for the production of its esters , which are used as preservatives .

Health hazards

4-Hydroxybenzoic acid was included by the EU in 2012 in accordance with Regulation (EC) No. 1907/2006 (REACH) as part of the substance evaluation in the Community's ongoing action plan ( CoRAP ). The effects of the substance on human health and the environment are re-evaluated and, if necessary, follow-up measures are initiated. The reasons for the uptake of 4-hydroxybenzoic acid were concerns about consumer use and high (aggregated) tonnage as well as the dangers arising from a possible assignment to the group of CMR substances and as a potential endocrine disruptor . The re-evaluation took place from 2014 and was carried out by the Czech Republic . A final report was then published.

Web links

OECD : Screening Information Dataset (SIDS) Initial Assessment Report (SIAR) for Benzoic acid, 4-hydroxy-

Individual evidence

↑ ^a ^b ^c ^d ^e Entry on 4-hydroxybenzoic acid. In: Römpp Online . Georg Thieme Verlag, accessed December 8, 2019.
↑ E. Winterstein, G. Trier: The alkaloids: a monograph of natural bases. Borntraeger, 1910, p. 305.
↑ Entry on 4-HYDROXYBENZOIC ACID in the CosIng database of the EU Commission, accessed on March 21, 2020.
↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Entry on 4-hydroxybenzoic acid in the GESTIS substance database of the IFA , accessed on December 8, 2019(JavaScript required) .
↑ ^a ^b Data sheet 4-hydroxybenzoic acid (PDF) from Carl Roth , accessed on May 1, 2009.
↑ CRC Handbook of Tables for Organic Compound Identification . Third Edition, 1984, ISBN 0-8493-0303-6 .
^ CA Wachtmeister: Studies on the Chemistry of Lichens. X. The Structure of Porphyrilic Acid. In: Acta Chem. Scand. 10, 1956, pp. 1404-1413, doi : 10.3891 / acta.chem.scand.10-1404 , ( PDF ; 1.4 MB).
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-288.
↑ Walter Karrer : Constitution and occurrence of organic plant substances. Springer, 1958, ISBN 978-3-0348-6795-5 (reprint), p. 356.
↑ YPS Bajaj: Medicinal and Aromatic Plants VIII. Biotechnology in Agriculture and Forestry 33, Springer, 1995, ISBN 978-3-642-08201-6 , p. 142 f.
^ Association of authors: Organikum . 19th edition, Johann Ambrosius Barth, Leipzig / Berlin / Heidelberg 1993, ISBN 978-3-335-00343-4 , pp. 351-352.
^ European Chemicals Agency (ECHA): Substance Evaluation Report and Conclusion Document .
↑ Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): 4-hydroxybenzoic acid , accessed on March 26, 2019.

[Roempp-1] Entry on 4-hydroxybenzoic acid. In: Römpp Online . Georg Thieme Verlag, accessed December 8, 2019.

[2] E. Winterstein, G. Trier: The alkaloids: a monograph of natural bases. Borntraeger, 1910, p. 305.

[CosIng-3] Entry on 4-HYDROXYBENZOIC ACID in the CosIng database of the EU Commission, accessed on March 21, 2020.

[GESTIS-4] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Entry on 4-hydroxybenzoic acid in the GESTIS substance database of the IFA , accessed on December 8, 2019(JavaScript required) .

[cr-5] Data sheet 4-hydroxybenzoic acid (PDF) from Carl Roth , accessed on May 1, 2009.

[CRC-6] CRC Handbook of Tables for Organic Compound Identification . Third Edition, 1984, ISBN 0-8493-0303-6 .

[Wachtmeister-7] CA Wachtmeister: Studies on the Chemistry of Lichens. X. The Structure of Porphyrilic Acid. In: Acta Chem. Scand. 10, 1956, pp. 1404-1413, doi : 10.3891 / acta.chem.scand.10-1404 , ( PDF ; 1.4 MB).

[CRC_90-8] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-288.

[9] Walter Karrer : Constitution and occurrence of organic plant substances. Springer, 1958, ISBN 978-3-0348-6795-5 (reprint), p. 356.

[10] YPS Bajaj: Medicinal and Aromatic Plants VIII. Biotechnology in Agriculture and Forestry 33, Springer, 1995, ISBN 978-3-642-08201-6 , p. 142 f.

[11] Association of authors: Organikum . 19th edition, Johann Ambrosius Barth, Leipzig / Berlin / Heidelberg 1993, ISBN 978-3-335-00343-4 , pp. 351-352.

[12] European Chemicals Agency (ECHA): Substance Evaluation Report and Conclusion Document .

[13] Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): 4-hydroxybenzoic acid , accessed on March 26, 2019.