Introduction to resins

1. 1
Definition, classification, properties and
test for identification of Resins
Presented by: Dr. Mohini Chetan Kuchekar
Assistant Professor
Department of Pharmacognosy
E-mail-ID: mohini.kuchekar@gmail.com
Contact: +919970289735

2. Learner will be able to:
• Understand what are Resins.
• Describe occurrence and properties of Resins.
• Classify Resins with examples
• Chemical test of Resins
• Functions of Resins
2
Learning Outcomes:

3. Content
3
• Definition
• Occurrence
• Properties
• Classification
• Chemical test for identification of Resins
• Functions

4. Resins
• Resins in the most specific use of the term is a
hydrocarbon secretion of many plants, particularly
coniferous trees.
• It is distinct from other liquid compounds found inside
plants or exuded by plants, such as sap, latex, or
mucilage.

5. Resins are amorphous solid or semisolid
substances that are invariably water insoluble but
mostly soluble in alcohol or other organic
solvents.
Definition:

6. • In the plants resins usually occur in different secretary
zones or structures.
• Resin Cells: Ginger–Zingiber officinale (Family: Zingiberaceae);
• Schizogenous Ducts: Pine Wood–Pinus polustris (Family: Pinaceae).
• Glandular Hairs: Cannabis–Cannabis sativa (Family: Moraceae)
• The formation of resins in the plant is by virtue of its
normal physiological functions. However its yield may
be enhanced in certain exceptional instances by
inflicting injury to the living plant for instance: Pinus.
Occurrence:

7. • Many resisnous products are not formed by the plant itself
unless and until purposeful and methodical injuries in the
shape of incisions are made on them and the secretion or
plant exudates are tapped carefully such as: Balsam of Talu
and Benzoin.
• In other words these resins are of pathological origin.
• One school of thought has categorically termed the secretion
exclusively obtained from the naturally occurring secretory
structure as the Primary Flow.
• Whereas the one collected through man-made-incisions on
the plant i.e. abnormally formed secretary structures as the
Secondary Flow.

8. Properties
Physical Properties of Resins:
• Resins are hard transparent or translucent brittle materials.
• They are invariably heavier than water having the specific gravity
ranging from 0.9-1.25.
• Resins are more or less amorphous materials but rarely
crystallisable in nature.
• On being heated at a relatively low temperature resins first get
softened and ultimately melt down thereby forming either an
adhesive or a sticky massive fluid without undergoing any sort of
decomposition or volatilization.

9. •On being heated in a closed container i.e. in the absence of
oxygen they undergo decomposition and very often give rise to
empyreumatic products i.e. products chiefly comprising of
hydrocarbons.
•Resins are bad conductors of electricity but when rubbed
usually become negatively charged.
•On being heated in the air i.e. in the presence of oxygen resins
usually burn readily with a smoky flame by virtue of the
presence of a large number of C-atoms in their structure.
•They are practically insoluble in water but frequently soluble in
ethanol volatile oils fixed oils chloral hydrate and non-polar
organic solvents e.g. benzene n-hexane and petroleum ether.

10. Chemical Properties of Resins:
• Resins in general are enriched with carbon deprived of
nitrogen and contain a few oxygen in their respective
molecules.
• Majority of them undergo slow atmospheric oxidation.
• Resins are found to be a mixture of numerous compounds
rather than a single pure chemical entity.
• Their chemical properties are exclusively based upon the
functional groups present in these substances.

11. • Consequently the resins are broadly divided into resin
alcohols, resin acids, resin esters, glycosidal resins and
resenes (i.e. inert neutral compounds).
• It is also believed that resins are nothing but oxidative
products of terpenes.
• They may also be regarded as the end-products of
destructive metabolism.
• The acidic resins when treated with alkaline solutions they
yield soaps (or resin-soaps).

12. Classification of Resins
Resins are
classified in
Four different
ways
a) On the basis
of their
formation
b) On the
basis of
chemical
nature
c) On the basis
of occurrence
with other
secondary
metabolites
d)
Taxanomical
Classificatio
n

13. a) On the basis of their formation:
Physiological resins –
These are formed as a
normal product of
metabolism without
making injury to the plants
Pathological Resins –
Formed as a result of
wound injury or abnormal
circumstances e.g: benzoin
colophony balsams aloe
resin etc.

14. b) On the basis of chemical nature
• Resin acids: Here the resins occur along with their acids e.g.
Colophony and Copaiba.
• Resin alcohols: They occurs as in free state or as esters
examples – Balsam of peru with perru resino tannol ,Guaiaccum
resin with guaic resinol.
• Ester resins: This group contains esters as the chief constituents
of the resins e.g. Asafoetida, Benzoin, Balsam of Peru and Tolu.
• Resenes: stable neutral unaffected by most chemical reagents
or by exposure to moisture produced a hard film. e.g. asafetida.
• Resin phenols: This group contains phenol as the chief
constituents resinotannols

15. c) On the basis of occurrence with other secondary
metabolites
• Oleo-resins: Resin and oils in homogenous mixtures are called
as oleoresin e.g: copaiba, Canada balsam, capsicum. ginger.
• Gum resins: It is a resin associated with gum e.g: Garcinia
hanburyi.
• Oleo-gum-resins: It is homogenous mixtures of volatile oil, gum
and resin e.g: Myrrh, Guggul, asafetida.
• Glycoresins: it is made up of resins and sugar and present in
jalap and ipomoea. Balsams are resinous mixtures that contain
large proportions of cinnamic acid, benzoic acid or both or
esters of these acids.
• The term “balsam” is often wrongly applied to oleoresins and
should be reserved for such substances as balsam of Peru,
balsam of Tolu and storax, which contain a high proportion of
aromatic balsamic acids. e.g: balsam of Tolu, balsam of Peru.

16. d) On the basis of Taxanomical Classification:
These resins are grouped together according to their
origin:
 Coniferous resins: Eg- Colophony and Sandarac
 Zygopyllacceae Resins: Eg- Guaiacum
 Berberidaceae Resins: Eg- Podophyllum.

17. Chemical test for identification of Resins:
1.When sample is treated
with hydrochloric acid it
will gives pink colour due
to presence of resin.
2. When sample is treated
with ferric chloride
solution it will gives
greenish blue colour due
to presence of resin.

18. Role of Resins :
• It is local irritant and hence act as local cathartics (e.g.
Jalap and Ipomea)
• It is used as anti cancer (Podophyllum) and bronchial
asthma (e.g. Cannabis)
• It is used externally as mild antiseptic in the form of
tinctures (Benzoin) ointment and plasters (Turpentine and
Colophony)
• It is used in the preparation of emulsion and sustained
released formulations

19. Summary
19
• Definition of Resins.
• Occurrence and Properties of Resins.
• Classification of Resins
• Chemical test of Resins
• Functions of Resins

20. 20
Thank You…