Salicylaldehyde

Source: Wikipedia, the free encyclopedia.
Salicylic aldehyde
Skeletal formula
Skeletal formula
Ball-and-stick model
Ball-and-stick model
Names
Preferred IUPAC name
2-Hydroxybenzaldehyde[1]
Other names
Salicylaldehyde
Salicylic aldehyde
o-Hydroxybenzaldehyde
Identifiers
3D model (
JSmol
)
471388
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.001.783 Edit this at Wikidata
EC Number
  • 201-961-0
3273
KEGG
UNII
  • InChI=1S/C7H6O2/c8-5-6-3-1-2-4-7(6)9/h1-5,9H checkY
    Key: SMQUZDBALVYZAC-UHFFFAOYSA-N checkY
  • InChI=1/C7H6O2/c8-5-6-3-1-2-4-7(6)9/h1-5,9H
    Key: SMQUZDBALVYZAC-UHFFFAOYAD
  • O=Cc1ccccc1O
Properties
C7H6O2
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:
GHS07: Exclamation markGHS09: Environmental hazard
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).
checkY verify (what is checkY☒N ?)

Salicylic aldehyde (2-hydroxybenzaldehyde) is an

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]

Preparation of salicylaldehyde by the Reimer–Tiemann reaction

Natural occurrences

Salicylaldehyde was identified as a characteristic aroma component of buckwheat.[7]

It is also one of the components of

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.[4]

Catechol, benzofuran, a salicylaldehydimine (R = alkyl or aryl), 3-carbethoxycoumarin
  1. Oxidation with
    Dakin reaction).[9]
  2. Rap–Stoermer condensation after E. Rap (1895) and R. Stoermer (1900).[11][12]
  3. Salicylaldehyde is converted to chelating ligands by condensation with amines. With ethylenediamine, it condenses to give the ligand salen. Hydroxylamine gives salicylaldoxime.
  4. 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.

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

  1. ISBN 978-0-85404-182-4
    .
  2. ^ a b Sigma-Aldrich Co., Salicylaldehyde. Retrieved on 2018-05-24.
  3. ^ Merck Index, 11th Edition, 8295
  4. ^
    ISBN 978-0-471-48494-3
    .
  5. doi:10.15227/orgsyn.089.0220
    .
  6. ISBN 978-3527306732.{{cite encyclopedia}}: CS1 maint: multiple names: authors list (link
    )
  7. PMID 26003350
    .
  8. ^ 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.
  9. ^ Dakin, H. D. (1923). "Catechol" (PDF). Organic Syntheses. 3: 28; Collected Volumes, vol. 1, p. 149.
  10. doi:10.15227/orgsyn.046.0028{{cite journal}}: CS1 maint: multiple names: authors list (link
    )    .
  11. ^ Rap, E. (November 1895). "Sull' α-Benzoilcumarone" [On the α-Benzoylcoumaron]. Gazzetta Chimica Italiana. 2 (4): 285–290.
  12. doi:10.1002/jlac.19003120302
    .
  13. doi:10.15227/orgsyn.028.0024{{cite journal}}: CS1 maint: multiple names: authors list (link
    ).
  14. doi:10.1016/j.eurpolymj.2023.112209
    .
  15. doi:10.1021/ja00539a017
    .
  16. doi:10.1002/anie.201306775
    .
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