Description
3,4-methylphenol (also 3,4-xylenol) has a flat, dry odor. It can be used as a flavoring agent without safety concern at current levels of intake. 3,4-dimethylphenol is used as an agent in the spectrophotometric method to determine nitrate in plants, soils, and water. It is also used to produce adhesive/sealant and resins as negative photoresist for electroplating.
References
[1] R. R. Elton-Bott, A modified spectrophotometric method for nitrate in plants, soils and water by nitration of 3,4-dimethylphenol, Analytica Chimica Acta, 1977, vol. 90, 215-221
[2] George A. Burdock, Fenaroli’s Handbook of Flavor Ingredients, Sixth Edition, 2010
[3] Chia L. Wang, John Davis, Bryan Lienke, Polyurethane systems having non-sag paintability and primerless adhesion on concrete, Patent, 2012
[4] Yasuo Masuda, Yasushi Washio, Koji Saito, Method of forming plated product using negative photoresist composition and photosensitive composition used therein, Patent, 2012
Chemical Properties
YELLOW TO BROWNISH CRYSTALLINE MASS
Occurrence
Reported found in coffee, tomato, parmesan and romano cheese, smoked fatty fish, white wine, katsuobushi
(dried bonito) and wood vinegar.
Uses
Applications of 3,4-dimethylphenol:
- It can react with ethyl cinnamates in trifluoroacetic acid to form the corresponding dihydrocoumarin derivatives.
- Bromination of 3,4-dimethylphenol using bromine can lead to 6-bromo-3,4-dimethylphenol.
- It can react with 1-fluoro-4-chloromethyl-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoro-borate) (Selectfluor? F-TEDA-BF4) to form 4-fluoro-3,4-dimethylcyclohexa-2,5-dienone.
Definition
ChEBI: 3,4-xylenol is a member of the class of phenols that is phenol substituted by methyl groups at positions 3 and 4. It derives from a hydride of an o-xylene.
Aroma threshold values
Detection: 1.2 ppm
General Description
Colorless to light tan crystalline powder or solid. Odor threshold 1.2 mg/L. Taste threshold 0.05 mg/L.
Air & Water Reactions
Hygroscopic. Insoluble in water.
Reactivity Profile
3,4-Dimethylphenol is incompatible with bases, acid chlorides, acid anhydrides, and oxidizing agents. 3,4-Dimethylphenol corrodes steel, brass, copper, and copper alloys.
Fire Hazard
Flash point data for 3,4-Dimethylphenol are not available. 3,4-Dimethylphenol is probably combustible.
Purification Methods
Heat 3,4-xylenol with an equal weight of conc H2SO4 at 103-105o for 2-3hours, then dilute it with four volumes of water, reflux it for 1hour, and either steam distil or extract it repeatedly with diethyl ether after cooling to room temperature. The steam distillate is also extracted and evaporated to dryness. (The purification process depends on the much slower sulfonation of 3,4-dimethylphenol than most of its likely contaminants.). It can also be crystallised from water, hexane or pet ether, and sublimed in a vacuum. [Kester Ind Eng Chem (Anal Ed) 24 770 1932, Bernasconi & Paschalis J Am Chem Soc 108 29691986, Beilstein 6 IV 3099.]
Toxics Screening Level
The current initial threshold screening level (ITSL) for 3,4-dimethylphenol is 3.5 μg/m3 based on an annual averaging time.
