M-Thymol

SYNS P-CYMEN-3-OL 3-p-CYMENOL 3-HYDRO-XY-p-CYMENE 3-HYDROXY-1-METHYL-4-ISOPROP-YLBENZENE ISOPROPYL CRESOL 6-ISOPROPYL-m-CRESOL 2-ISOPROPYL-5-METHYLPHENOL 1-METHYL-3-HYDROXY-4-ISOPROPYLBENZENE 5-METHYL-2-ISOPROPYL-1-PHENOL 5-METHYL-2-(l-METHYLETHYL)PHENOL THYME CAMPHOR THYMIC ACID m-THYMOL... 

Addo trimico 3-p-cymenol p-cymen-3-ol Flavinol 3-hydroxy-p-cymene 3-hydroxy-l-methyl-4-isopropylbenzene Intrasol isopropyl cresol isopropyl-w-cresol 6-isopropyl-m-cresol isopropyl metacresol 2-isopropyl-5-methylphenol 1-methyl-3-hydroxy-4-isopropylbenzene 5-methyl-2-isopropyl-phenol 5-methyl-2-(l-methylethyl) phenol Medophyll thyme camphor thymic acid m-thymol timol. 

Verghese has published a review about this class. Authentically naturally occurring m-menthanes are m-thymol (687, R = H) and its methyl ether 687 (R = Me), isolated from various Calea species as well as the isobutyl ether 687 (R = iBu) from Athrixia elata. Paknikar has synthesized 687 (R = H) by Grignard reaction of 2-hydroxy-5-methylacetophenone. ... 

AI3-00708 Caswell No. 856A CCRIS 7299 Cymo-phenol, a- EINECS 201-944-8 ERA Pesticide Chemical Code 080402 FEMA Number 3066 HSDB 866 Isopropyl cresol NSC 11215 Thyme camphor Thymic acid Thymol m-Thymol Thymol (natural). An antibacterial and antifungal agent used in perfumery, microscopy, preservative, antioxidant, flavoring, as a laboratory reagent, in the manufacture of menthol. Used in the prevention of mold and mildew, in flavoring and perfumery, as a preservative and antioxidant and a topical antiseptic. Crystalline solid mp = 51,5° bp = 232.5" dl ... 

Methyl-2-isopropylphenol 5-Methyl-2-(1-methylethyl) phenol Phenol, 5-methyl-2-(1-methylethyl)- Thyme camphor Thymic acid m-Thymol... 

Synonyms 5-Methyl-2-(l-methylethyl)phenol 3-p-cymenol 3-hydroxy-p-cymene thyme camphor m-thymol isopropylmeta cresol timol Trade names Bensulfold... 

The latest patent for the preparation of artificial thymol is that of E. M. Cole (U.S.P. 1,378,939, 24 May, 1921). His method consists essentially in the electrolytic reduction of nitro-cymene in the presence of sulphuric acid, and the subsequent diazotisation and reduction of the para-amidocymenol produced, by e ctric action, involving the use of stannous chloride. 

Jod-saure, /, iodic acid, -schwefel, m. sulfur iodide, -serum, n. iodized serum, -silber, n. silver iodide, -silizium, n. silicon iodide. -stSrke, /. starch iodide, iodized starch. -stSrkepapier, n. starch iodide paper, -stick-stoff, m. nitrogen iodide, -thymol, n.iPhaTm.) thymol iodide, -tinktur,/. tincture of iodine, -toluol, n. iodotoluene. -iibertrilger, m. iodine carrier. 

Sulphonphthaleins. These indicators are usually supplied in the acid form. They are rendered water-soluble by adding sufficient sodium hydroxide to neutralise the sulphonic acid group. One gram of the indicator is triturated in a clean glass mortar with the appropriate quantity of 0.1 M sodium hydroxide solution, and then diluted with water to 1 L. The following volumes of 0.1 M sodium hydroxide are required for 1 g of the indicators bromophenol blue, 15.0 mL bromocresol green, 14.4 mL bromocresol purple, 18.6 mL chlorophenol red, 23.6 mL bromothymol blue, 16.0 mL phenol red, 28.4 mL thymol blue, 21.5 mL cresol red, 26.2 mL metacresol purple, 26.2 mL. 

Pipette 25 mL barium ion solution (ca 0.01 M) into a 250 mL conical flask and dilute to about 100 mL with de-ionised water. Adjust the pH of the solution to 12 by the addition of 3-6 mL of 1M sodium hydroxide solution the pH must be checked with a pH meter as it must lie between 11.5 and 12.7. Add 50 mg of methyl thymol blue/potassium nitrate mixture [see Section 10.50(C)] and titrate with standard (0.01 M) EDTA solution until the colour changes from blue to grey. 

However, for m-cresol purple, thymol blue and o-nitroaniline, many estimated K, values yielded straight lines with eqn. 4.77, so that with these indicators the spectrophotometric method failed. This result led Bos to check some of the above results by means of the potentiometric method of Tanaka and Nakagawa64 applied to titrations in glacial acetic acid also he obtained the following data ... 

The synthetic process starts with the isopropylation of m-cresol to yield thymol. After catalytic hydrogenation a mixture of stereoisomers is obtained from which (+)-menthol is isolated. The process requires much separation and recycling work. In contrast, the semi-synthetic process of Takasago (Scheme 5.5) leads essentially to stereopure (—)-menthol [19]. 

Standardization of 0.1 M Tetrabutylammonium Hydroxide To 10 ml of dimethylformamide add 0.05 ml of a 0.3 % w/v solution of thymol blue in methanol and titrate with the tetrabutylammonium hydroxide solution until a pure blue colour is produced. Immediately add 0.2 g of benzoic acid, stir to effect solution and titrate with the tetrabutylammonium hydroxide solution until the pure blue colour is restored. Protect the solution from atmospheric C02 throughout the titration. The volume of titrant used in the second titration represents the amount of tetrabutylammonium hydroxide required. Each ml of 0.1 M tetrabutylammonium hydroxide Vs is equivalent to 12.21 mg of C7Hg02. 

Eluent buffers A 0.067 M sodium citrate, 0.33 mM thymol, pH 3.0, except pH 5.0 for furosine analysis B 0.25 M sodium nifrafe, 0.024 M boric acid, pH 10.2 (pH adjusted with NaOH and HNO3). 

Scheme 1. Possible reaction pathways from m-cresol to thymol.

Figure 4. LC separation of a terpene mixture. 1, Thymol 2, p-cymene 3, y-terpinene 4, a-terpinene 5, 3-pinene 6, a-pinene. Column 30 cm x 0.22 mm I.D. 3-ym Spherisorb ODS. Mobile phase methanol-water (80 20) Detection TIC (ions of m/z <40 suppressed).

Cresol red Crystal Violet Malachite Green Methanil Yellow Thymol Blue Orange IV -2,4-Dinitrophenol -Erythrosin, Na2 salt -Dimethyl Yellow Cl 11020 Bromophenol Blue Congo Red Cl 22120 Methyl Orange Bromocresol Green Alizarin Red S Cl 42750 Methyl Red Cl 13020 -Bromocresol Purple Chlorophenol Red p-Nitrophenol Alizarin Bromothymol Blue Brillant Yellow Phenol Red Neutral Red Cl 50040 -m-NItrophenol -Cresol Red Metacresol Purple Phenolphthalein -Thymolphthalein -P-Naphthyl Violet Alizarin Yellow R 2,4,6-T rinitrotoluene... 

The crude thymol mixture, consisting of approximately 60% thymol, unreacted m-cresol (ca. 25%), and other (iso)propyl-substituted products, is separated by fractional distillation. Most of the byproducts are recycled. 

Alkylation of m-cresol with propene in the presence of an aluminium catalyst results in the formation of thymol, which upon hydrogenation gives a rnkture of all eight isomers of menthol, D-menthol, L-menthol, neomenthol, isomenthol and neoisomenthol (Scheme 13.3). The preferred isomer is L-menthol, because of its ability to induce physiologically the sense of cold which is desired in many products such as chewing gum and toothpaste L-menthol is about... 

Methyl Thymol Blue, sodium salt [1945-77-3] M 844.8, e 1.89 x 1(H at 435nm, pH 5.5. Starting material for synthesis is Thymol Blue. Purified as for Xylenol Orange. 

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