Phthalaldehyde

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Phthalaldehyde
Skeletal formula of O-phthaldehyde Ball-and-stick model
Identifiers
CAS number 643-79-8 YesY
PubChem 4807
ChemSpider 4642 N
ChEBI CHEBI:70851 N
RTECS number TH6950000
Jmol-3D images Image 1
Properties
Molecular formula C8H6O2
Molar mass 134.13 g mol−1
Appearance Yellow solid
Density 1.19 g/mL
Melting point 55.5 to 56 °C (131.9 to 132.8 °F; 328.6 to 329.1 K)[1]
Boiling point 266.1 °C (511.0 °F; 539.2 K)
Solubility in water Low
Hazards
R-phrases R25 R34 R43 R50[2]
S-phrases S26 S36/37/39 S45 S61 [2]
Main hazards Toxic, Irritant
Flash point 132 °C (270 °F; 405 K)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

o-Phthalaldehyde or ortho-phthalaldehyde is the chemical compound with the formula C6H4(CHO)2. Often abbreviated OPA, the molecule is a dialdehyde, consisting of two formyl (CHO) groups attached to adjacent carbon centres on a benzene ring. This pale yellow solid is a building block in the synthesis of heterocyclic compounds and a reagent in the analysis of amino acids.

Synthesis[edit]

The molecule was first described in 1887 when it was prepared from α,α,α’,α’-tetrachloro-ortho-xylene.[3] A more modern synthesis is similar: the hydrolysis of the related tetrabromoxylene using potassium oxalate, followed by purification by steam distillation.[1] The reactivity of OPA is complicated by the fact that with water it forms both a mono- and dihydrate, C6H4(CHO)(CH(OH)2) and C6H4(CH(OH))2O, respectively.[4]

Orthophthalaldehyde and hydrated forms 001.png

Isomeric phthalaldehydes[edit]

Related to ortho-phthalaldehyde are the meta- and para-isomers, which are respectively named isophthalaldehyde (m.p. 87–88 °C, CAS# 626-19-7) and terephthalaldehyde (m.p. 114–116 °C, CAS# 623-27-8).

Biochemistry[edit]

OPA is well soluble, and stable in water solution at pH < 11.5. It is however sensitive to UV illumination and air oxidation.

OPA is used as a very sensitive fluorescent reagent for assaying amines or sulfhydryls in solution, notably contained in proteins, peptides, and amino acids, by capillary electrophoresis and chromatography. OPA reacts specifically with primary amines above their isoelectric point Pi in presence of thiols. OPA reacts also with thiols in presence of an amine such as n-propylamine or 2-aminoethanol. The method is spectrometric (fluorescent emission at 436-475 nm (max 455 nm) with excitation at 330-390nm (max. 340 nm)).[5]

Disinfection[edit]

OPA is commonly used as a high-level disinfectant for medical instruments. Disinfection with OPA is indicated for semi-critical instruments that come into contact with mucous membranes or broken skin, such as specula, laryngeal mirrors, and internal ultrasound probes.[6]

Poly(phthalaldehyde)[edit]

OPA can be polymerized. In the polymer, one of the oxygen atoms forms a bridge to the other non-ring carbon of the same phthalaldehyde unit, while the other bridges to a non-ring carbon of another phthalaldehyde unit. Poly(phthalaldehyde) is used in making a photoresist.[7]

In winemaking[edit]

The Nitrogen by O-Phthaldialdehyde Assay (NOPA) is one of the methods used in winemaking to measure yeast assimilable nitrogen (or YAN) needed by wine yeast in order to successfully complete fermentation.[8]

References[edit]

  1. ^ a b J. C. Bill and D. S. Tarbell (1954), "o-Phthalaldehyde", Org. Synth. 34: 82 ; Coll. Vol. 4: 807 
  2. ^ a b Phthaldialdehyde from Sigma-Aldrich
  3. ^ Colson, A.; Gautier, H. (1887). "Nouveau Mode de Chloruration des Carbures". Annales de Chimie 6 (11): 28. 
  4. ^ Zuman, Petr (2004). "Reactions of Orthophthalaldehyde with Nucleophiles". Chemical Reviews 104 (7): 3217–38. doi:10.1021/cr0304424. PMID 15250740. 
  5. ^ Protocol by Uptima
  6. ^ "Infection Control in the Physician's Office". College of Physicians and Surgeons of Ontario. 2004. 
  7. ^ Tsuda, M.; Hata, M.; Nishida, R. I. E.; Oikawa, S. (1993). "Chemically amplified resists IV. Proton-catalyzed degradation mechanism of poly(phthalaldehyde)". Journal of Photopolymer Science and Technology 6 (4): 491. doi:10.2494/photopolymer.6.491.  edit
  8. ^ B. Zoecklein, K. Fugelsang, B. Gump, F. Nury Wine Analysis and Production pgs 152-163, 340-343, 444-445, 467 Kluwer Academic Publishers, New York (1999) ISBN 0834217015