PPT-Phenols and Tannins Pharmacognosy I

Mosul University College of Pharmacy LA Dilbreen Barzanji Phenols and phenolic glycosides Phenols probably constitute the largest group of plant secondary metabolites Widespread in nature and to be found in most classes of natural compounds having aromatic moieties they range from simple structures with one aromatic ring to highly complex polymeric substances such as tannins and . Faculty of Pharmacy GRDPGIMT Rajpur Road Dehradun Uttarakhand India Email kupraveensifycom 2 Faculty of Pharmacy Kumaun University Bhimtal Nainital Uttarakhand India Tannins are obtained upon the decomposition of vegetation They will generally be Ar. -OH). Phenols . are compounds of the general formula . Ar. -OH, where . Ar. - is phenyl, substituted phenyl, or one of the other aryl groups. . I. Structure . and nomenclature:. Phenols . differ from alcohols in having the -OH group attached directly to an aromatic . Alcohol . – alkyl chain attached to an –OH. . R-OH. Phenol . - aromatic attached to an –OH. Nomenclature. 1. Name the longest chain of carbons which includes the carbon with the hydroxyl group.. Thiols. , . and ethers. Nomencalture. of alcohols. Use the end . ol. Examples. . Hydrogen bonding in alcohols and phenols. Alcohols and phenols form hydrogen bonds, and hence they have relatively high boiling points. This also makes the lower alcohols miscible with water. As the R group becomes larger, the solubility of alcohols in water decreases dramatically.. Stephanie Diamond, Emilee Landers, Andrea Sierra-. Cadavid. What are tannins?. Large molecular weight phenolic compounds. Condensed and . Hydrolyzable. c. hemistry.about.com. Chemistry of Tannins. Hydrolyzable. . Complex organic, non-nitrogenous plant products.. Derivatives of polyhydroxy benzoic acid (polyphenols).. Ability to precipitate proteins. Having high molecular weight (500 to > 20000).. Historically, tannin containing drugs are related to their tanning property i.e. their ability to transform fresh hides into imputrescible leather.. Objective:. To know what phenol is. Success criteria:. Recognise phenol compounds. Recall . the reaction of phenol with bromine water. Compare the reactions of phenols to that of bromine. Explain the difference in reactivity between phenols and benzene. Afroz. . Lecturer. Daffodil International University. Pharmacognosy. is the study of medicinal drugs derived from plants or other natural sources. . . Or . Phenols are organic compounds with a hydroxyl group attached directly to an aromatic ring. They have the general formula . Ar. -OH. Examples of them include phenol, hydroquinone, resorcinol,. o. -cresol, . Role of . Pharmacognosy. in . allopathy. and traditional systems of medicine namely, . Ayurveda. , . Unani. , . Siddha. , Homeopathy and Chinese systems of medicine.. COMPILED BY . DR NISHA SHARMA. Cadavid. What are tannins?. Large molecular weight phenolic compounds. Condensed and . Hydrolyzable. c. hemistry.about.com. Chemistry of Tannins. Hydrolyzable. Tannins. Mainly . gallic. acid and related compounds. J. Princess . Gracia. , M.. Sc. .,M.Phil.,. Assistant Professor,. Department of . Chemistry,. Bon Secours College for Women, . Thanjavur. .. Introduction-. . Phenols also called as phenolics are a class of chemical compounds consisting of a hydroxyl group (-OH) bonded directly to an aromatic hydrocarbon group.. 3rd Class, 1st Semester. Introduction. Tannins are phenolic glycosides and . comprise of a large group of complex substances that are widely distributed in the plant kingdom.. Chemically tannins are complex substances that are difficult to separate because they do not crystallized.. 3rd Class, 1st Semester. Introduction. Tannins are phenolic . compounds . and . comprise of a large group of complex substances that are widely distributed in the plant kingdom.. Chemically tannins are complex substances that are difficult to separate because they do not crystallized..