From Wikipedia, the free encyclopedia
Salicylic aldehyde
Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name
2-Hydroxybenzaldehyde
[1]
Other names
Salicylaldehyde Salicylic aldehydeo -Hydroxybenzaldehyde
Identifiers
471388
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
100.001.783
EC Number
3273
KEGG
UNII
InChI=1S/C7H6O2/c8-5-6-3-1-2-4-7(6)9/h1-5,9H
Y Key: SMQUZDBALVYZAC-UHFFFAOYSA-N
Y InChI=1/C7H6O2/c8-5-6-3-1-2-4-7(6)9/h1-5,9H
Key: SMQUZDBALVYZAC-UHFFFAOYAD
Properties
C 7 H 6 O 2
Molar mass
122.123 g·mol−1
Density
1.146 g/cm3
Melting point
−7 °C (19 °F; 266 K)
Boiling point
196 to 197 °C (385 to 387 °F; 469 to 470 K)
-64.4·10−6 cm3 /mol
Hazards
[2]
GHS labelling :
Warning
H302 ,
H315 ,
H317 ,
H319 ,
H335 ,
H411
P280 ,
P305+P351+P338
Safety data sheet (SDS)
[2]
Related compounds
Related compounds
Salicylic acid
Benzaldehyde
Salicylaldoxime
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
Chemical compound
Salicylic aldehyde (2-hydroxybenzaldehyde) is an
organic compound with the formula C6 H4 OH(CHO) .
[3]
[4] Along with
3-hydroxybenzaldehyde and
4-hydroxybenzaldehyde , it is one of the three
isomers of
hydroxybenzaldehyde . This colorless oily liquid has a bitter almond odor at higher concentration. Salicylaldehyde is a precursor to coumarin and a variety of
chelating agents .
Production
Salicylaldehyde is produced by condensation of phenol with formaldehyde to give hydroxybenzyl alcohol, which is oxidized to the aldehyde.
[4]
Salicylaldehydes in general are prepared by ortho-selective
formylation reactions from the corresponding phenol, for instance by the
Duff reaction ,
Reimer–Tiemann reaction , or by treatment with
paraformaldehyde in the presence of
magnesium chloride and a base.
[5]
Salicylaldehyde can also be prepared from
phenol and
chloroform in a
Reimer–Tiemann reaction :
[6]
Natural occurrences
Salicylaldehyde was identified as a characteristic aroma component of
buckwheat .
[7]
It is also one of the components of
castoreum , the exudate from the castor sacs of the mature North American beaver (
Castor canadensis ) and the European beaver (
Castor fiber ), used in perfumery.
Furthermore, salicylaldehyde occurs in the larval defensive secretions of several
leaf beetle species that belong the subtribe Chrysomelina.
[8] An example for a leaf beetle species that produces salicylaldehyde is the red poplar leaf beetle
Chrysomela populi .
Reactions and applications
Salicylaldehyde is mainly used commercially as a precursor to
coumarin . The conversion entails condensation with
acetic anhydride ("
Perkin synthesis ").
[4]
Catechol ,
benzofuran , a salicylaldehydimine (R = alkyl or aryl), 3-carbethoxycoumarin
Oxidation with
hydrogen peroxide gives
catechol (1,2-dihydroxybenzene) (
Dakin reaction ).
[9]
Etherification with
chloroacetic acid followed by cyclisation gives the heterocycle
benzofuran (coumarone).
[10] The first step in this reaction to the substituted benzofuran is called the
Rap–Stoermer condensation after E. Rap (1895) and R. Stoermer (1900).
[11]
[12]
Salicylaldehyde is converted to
chelating
ligands by condensation with amines. With
ethylenediamine , it condenses to give the ligand
salen . Hydroxylamine gives
salicylaldoxime .
Condensation with
diethyl malonate gives 3-carbethoxycoumarin (a derivative of
coumarin ) by an
aldol condensation .
[13]
Internal hydrogen bonding
Due to the ortho positioning of the hydroxy- and aldehyde groups, an internal
hydrogen bond is formed between the groups. The hydroxy group serves here as the hydrogen bond donor, and the aldehyde as hydrogen bond acceptor. This internal hydrogen is not found in the other
hydroxybenzaldehyde isomers.
When the aldehyde is reacted with an amine to form an imine, the internal hydrogen bond is even stronger.
[14] In addition,
tautomerisation further increases the stability of the compound.
[15] The internal hydrogen bond also ensures that the aldehyde (or corresponding imine) is held into the same plane, making the whole molecule essentially flat.
[16]
References
^ "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) . Cambridge:
The Royal Society of Chemistry . 2014. p. 652.
doi :
10.1039/9781849733069-FP001 .
ISBN
978-0-85404-182-4 .
^
a
b
Sigma-Aldrich Co. ,
Salicylaldehyde . Retrieved on 2018-05-24.
^ Merck Index , 11th Edition, 8295
^
a
b
c Maliverney, Christian; Mulhauser, Michel (2000). "Hydroxybenzaldehydes". Kirk-Othmer Encyclopedia of Chemical Technology .
doi :
10.1002/0471238961.0825041813011209.a01 .
ISBN
978-0-471-48494-3 .
^ Trond Vidar Hansen; Lars Skattebøl (2005). "Ortho-Formylation of Phenols; Preparation of 3-Bromosalicylaldehyde".
Organic Syntheses . 82 : 64.
doi :
10.15227/orgsyn.089.0220 .
^ Brühne, F.; Wright, E. "Benzaldehyde".
Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH.
doi :
10.1002/14356007.a03_463.pub2 .
ISBN
978-3527306732 . {{
cite encyclopedia }}
: CS1 maint: multiple names: authors list (
link )
^ Janeš, D.; Kreft, S. (2008). "Salicylaldehyde is a characteristic aroma component of buckwheat groats".
Food Chemistry . 109 (2): 293–298.
doi :
10.1016/j.foodchem.2007.12.032 .
PMID
26003350 .
^ Pauls, G., Becker, T., et al. (2016).
Two Defensive Lines in Juvenile Leaf Beetles; Esters of 3-nitropropionic Acid in the Hemolymph and Aposematic Warning. Journal of Chemical Ecology 42 (3) 240-248.
^ Dakin, H. D. (1923).
"Catechol" (PDF) .
Organic Syntheses . 3 : 28 ; Collected Volumes , vol. 1, p. 149 .
^ Burgstahler, A. W.; Worden, L. R. (1966). "Coumarone".
Organic Syntheses . 46 : 28.
doi :
10.15227/orgsyn.046.0028 {{
cite journal }}
: CS1 maint: multiple names: authors list (
link ) .
^ Rap, E. (November 1895). "Sull' α-Benzoilcumarone" [On the α-Benzoylcoumaron].
Gazzetta Chimica Italiana . 2 (4): 285–290.
^ Stoermer, R. (1900).
"Synthesen und Abbaureactionen in der Cumaronreihe" .
Liebig's Annalen der Chemie . 312 (3): 237–336.
doi :
10.1002/jlac.19003120302 .
^ Horning, E. C.; Horning, M. G.; Dimmig, D. A. (1948). "3-Carbethoxycoumarin".
Organic Syntheses . 28 : 24.
doi :
10.15227/orgsyn.028.0024 {{
cite journal }}
: CS1 maint: multiple names: authors list (
link ) .
^ Schoustra, S.K.; Asadi, V.; Zuilhof, H.; Smulders, M.M.J. (2023).
"Internal hydrogen bonding of imines to control and enhance the dynamic mechanical properties of covalent adaptable networks" .
European Polymer Journal . 195 : 112209.
doi :
10.1016/j.eurpolymj.2023.112209 .
^ Metzler, C.M.; Cahill, A.; Metzler, D.E. (1980). "Equilibriums and absorption spectra of Schiff bases".
J. Am. Chem. Soc. 102 (19): 6075–6082.
doi :
10.1021/ja00539a017 .
^ Kandambeth, S.; Shinde, D.B; Panda, M.K.; Lukose, B.; Heine, T.; Banerjee, R. (2013).
"Enhancement of Chemical Stability and Crystallinity in Porphyrin-Containing Covalent Organic Frameworks by Intramolecular Hydrogen Bonds" .
Angew. Chem. Int. Ed. 52 (49): 13052–13056.
doi :
10.1002/anie.201306775 .