n-hexane,Chloroform,ethanol,water

n-hexan/Petrolium ether, chloroform, ethyl acetate, ethanol/methanol, water

The order is Petroleum ether, Chloroform, Diethyl ether, Ethyl acetate, n-butanol, Acetone, Methanol and water

Dear Zhu Liqiao,

I have confusion for placement of Diethyl ether and n-butanol. Bcz polarity index of both of these is less than polarity index of Chloroform. so, does it fit in series with respect to order of polarity index?

TO Vijayalakshmi · GITAM University,

can you plz explain why water should be first in this series???? Whatever I read was solvent should be in order of increasing polarity index.

Hexane - chloroform - acetone - methanol

Take a look in this book:

http://www.unido.org/fileadmin/user_media/Publications/Pub_free/Extraction_technologies_for_medicinal_and_aromatic_plants.pdf

Always start from non-polar solvents like hexane, eter petroleum,cyclo-hexane (this due that with nonpolar solvents you will break hydrophobic barriers ), and then increase the polarity --Chloroform-->Ethylacetate-->Ethanol-->Metanol.

What you are trying to achieve is successive partitioning. Usually, this should be done with solvent of least to highest polarity. The order should therefore be: pet ether, diethyl ether, ethyl acetate, chloroform, acetone, n- butanol, methanol and water. This order is according to increasing relative polarity.

@ Olorunfemi Eseyin: I have gone through polarity index of solvents in my question. Acording to that I found order of solvent as follow: pet ethr, diethyl ether, n-butanol, chloroform, ethyl acetate, acetonwe, methanol, water.

Will not it work?

Bhavikkumar Satani, I dont think the order you gave is correct. Please check again. Relative Polarity for those solvents are as follows: ether(0.117), ethyl acetate (0.228), chloroform (0.259), acetone(0.355), n-butanol (0.586), methanol (0.762) and water (1.000). Please, see the attached.

@ Olorunfemi Eseyin :

Thank you sir for your suggestion.

Actualy what I have referd was not relative polarity, it was just polarity of individual solvent. That values are different than what you have mentioned here.

But I like to go with article provided by you.

Thank you again sir.

Have a nice time.

Can you please give the reference (:for citation)of appendix that you have provided.

Its from the book, "Solvents and Solvent Effects in Organic Chemistry, Fourth Edition . Author(s): Prof. Dr. Christian Reichardt, Prof. Dr. Thomas Welton. Copyright © 2011 Wiley-VCH Verlag GmbH & Co. KGaA" Its available online. There are also many free online resources on this subject. I wish you the best

The order of polarity is very important in selecting the solvents for extraction with soxhlet apparatus. You should proceed from the non polar to polar solvent, means water should be the last solvent in any case with hexane/petroleum ether being the first to be used. The order for the solvents discussed in the question should be as follows:

Petroleum ether, diethylether, chloroform, acetone, ethyl acetate, n-butanol, methanol, water.

I am attaching a file which also shows many other solvents from non polar to polar range. Hope it might be useful for you.

Thank you Dr Nahata.

In selection of order from nonpolar to polar it seems easy to decide order of pet ether, diethyl ether,,.....,........then methanol, and water. But chloroform, acetone, ethyl acetate and n-butanol is confusing. Many answer in this discussion provided order to be used based on polarity of these solvents (chloroform, acetone, ethyl acetate and n-butanol) with appropriate reference.

Isn't it confusing???? Bcz if we change the reference, order will be change. I thought its a matter of polarity then it should not vary frm reference to reference.

In short which reference/literature we can rely on????

I am attaching a file which will clarify all your doubts regarding polarity of solvents.

Dr Nahata,

Thank you sir.

I also request you to refer solvent polarity provided by Olorunfemi Eseyin as pdf attachment.

Values of that document nd value in chart provided by you are different. What should be refered out of this two document?

I have just looked at the chart uploaded by Dr Alok and I observed that the information contained in it is at variance with the one given in the literature I uploaded on the same issue. I agree with you that there should be no confusion on the correct order of polarity of the solvents you listed. So, what do we do? The answer is simple: search for more information. That is what this forum is all about. For researchers to "rub" minds together, especially on issues like this, and eventually come up with the true picture. I am sure everything will be fine at the end of the day and our knowledge will be enriched.

Exactly I agree with Olorunfemi Eseyin and searching on the internet gave me another table of polarity indices of various solvents which is as follows:

Polarity Index (P´)

Pentane 0.0

1,1,2-Trichlorotrifluoroethane 0.0

Cyclopentane 0.1

Heptane 0.1

Hexane 0.1

Iso-Octane 0.1

Petroleum Ether 0.1

Cyclohexane 0.2

n-Butyl Chloride 1.0

Toluene 2.4

Methyl t-Butyl Ether 2.5

o-Xylene 2.5

Chlorobenzene 2.7

o-Dichlorobenzene 2.7

Ethyl Ether 2.8

Dichloromethane 3.1

Ethylene Dichloride 3.5

n-Butyl Alcohol 3.9

Isopropyl Alcohol 3.9

n-Butyl Acetate 4.0

Isobutyl Alcohol 4.0

Methyl Isoamyl Ketone 4.0

n-Propyl Alcohol 4.0

Tetrahydrofuran 4.0

Chloroform 4.1

Methyl Isobutyl Ketone 4.2

Ethyl Acetate 4.4

Methyl n-Propyl Ketone 4.5

Methyl Ethyl Ketone 4.7

1,4-Dioxane 4.8

Acetone 5.1

Methanol 5.1

Pyridine 5.3

2-Methoxyethanol 5.5

Acetonitrile 5.8

Propylene Carbonate 6.1

N,N-Dimethylformamide 6.4

Dimethyl Acetamide 6.5

N-Methylpyrrolidone 6.7

Dimethyl Sulfoxide 7.2

Water 10.2

According to this literature, the order of solvents in your question changes as follows:

Petroleum ether> ethyl ether> n-butanol> chloroform> ethyl acetate> Acetone=methanol> water.

This also suggests that you can use either acetone or methanol and this observation matches with the previous literature I uploaded.

Anyways good exercise. I think finally you will have to come up with a table made after summing up the results of all literature search and make it your in-house reference for future use.

I think the following link can help you if you can access the paper (I was not able to access it):

http://www.ncbi.nlm.nih.gov/pubmed/7310666

Gud Luck

Yes, Dr nahata. I allready have gone through polarity index that you have listed out. That's why I was confused what to do. I think doing literature we have to fix the value or find out justification of why values are different in litratures

Thnk you Olorunfemi Eseyin for involving in discussion

petroleum ether, ethyl acetate and methanolic extract which one shows most potent action

Hi, 

For any extraction, fundamentally solvent choice is form lower polar to highest polar i.e water is the sequence of choice for any extraction.

Definitely you are going to get the results if you floow the proper sequence, as I have got always the desired results.

Do properly sucess is yours.

Best luck.

Is there a standard method to extract all the phytochemicals into one solvent, or does it have to be extracted in different solvents?. Available from: https://www.researchgate.net/post/Is_there_a_standard_method_to_extract_all_the_phytochemicals_into_one_solvent_or_does_it_have_to_be_extracted_in_different_solvents#594c961deeae3950a67944ad [accessed Jun 23, 2017].

In case of preparation of medicinal plants extracts or isolation of organic molecules use successive extraction method by soxhlet app using non polar to polar solvents. Hexane/petroleum ether to methanol followed by chart showing the polarity in increasing order.Use plant material in soxhlet up to the level of solvent filled or siphon level