Thymol Blue sodium is an acid-base indicator that may be utilized to indicate changes in pH value. Thymol Blue sodium gradually changes from red to yellow at pH 1.2~2.8, and from yellow to blue at pH 8.0~9.6.

Physicochemical Properties

Molecular Formula	C27H29NAO5S
Molecular Weight	488.5709
Exact Mass	487.156
CAS #	62625-21-2
Related CAS #	76-61-9 (Parent)
PubChem CID	23692293
Appearance	Yellow to brown solid powder
Density	0.979 g/mL at 25 °C
Melting Point	283-285 °C (dec.)(lit.)
LogP	7.491
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	5
Rotatable Bond Count	4
Heavy Atom Count	34
Complexity	795
Defined Atom Stereocenter Count	0
InChi Key	BAVBEHWEOJMHDS-UHFFFAOYSA-M
InChi Code	InChI=1S/C27H30O5S.Na/c1-15(2)19-13-22(17(5)11-24(19)28)27(21-9-7-8-10-26(21)33(30,31)32-27)23-14-20(16(3)4)25(29)12-18(23)6;/h7-16,28-29H,1-6H3;/q;+1/p-1
Chemical Name	sodium;4-[3-(4-hydroxy-2-methyl-5-propan-2-ylphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]-5-methyl-2-propan-2-ylphenolate
Synonyms	Thymol Blue sodium salt; 62625-21-2; Thymolsulfonphthalein sodium salt; Thymol Blue, water soluble; MFCD00151093; Thymol Blue (sodium); Thymol Blue (Sodium Salt); sodium;4-[3-(4-hydroxy-2-methyl-5-propan-2-ylphenyl)-1,1-dioxo-2,1lambda6-benzoxathiol-3-yl]-5-methyl-2-propan-2-ylphenolate;
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

Targets	Acid-base indicator
References	[1]. Spectrophotometric pH measurements of surface seawater at in-situ conditions: absorbance and protonation behavior of thymol blue. Marine Chemistry,Volume 52, Issue 1,1996, Pages 17-25.
Additional Infomation	The proton exchange behavior of thymol blue (HI− ⇔ I2− + H+) and the molar absorbance characteristics of unprotonated (I2−) and protonated (HI−) forms of this indicator make thymol blue particularly well suited to pH observations in the upper ocean. In-situ Spectrophotometric measurements of seawater pH using sulfonephthalein indicators require assessment of the influence of temperature on indicator molar absorbance characteristics and the influence of temperature and salinity on indicator equilibrium characteristics. Our investigation of the physical/chemical behavior of thymol blue indicates that seawater pH can be described using the following equation: where pHT = − log[H+]T, [H+]T = [H+] + [HSO4−], (where λA is absorbance at wavelength λ), and e1= − 0.00132 + 1.600 × 10−5Te2 = 7.2326 − 0.0299717T+ 4.600 × 10−5 T2e3 = 0.0223 + 0.0003917 T Using the equations given above, K2 and [H+]T are expressed in units of .[1]

Solubility Data

Solubility (In Vitro)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Solubility (In Vivo)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples. Injection Formulations (e.g. IP/IV/IM/SC) Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] *Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline) Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline) Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline) Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil) Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Oral Formulations Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). Oral Formulation 3: Dissolved in PEG400 Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose Oral Formulation 6: Mixing with food powders Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.0468 mL	10.2339 mL	20.4679 mL
	5 mM	0.4094 mL	2.0468 mL	4.0936 mL
	10 mM	0.2047 mL	1.0234 mL	2.0468 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.