This invention relates to a process for producing vegetable dyes from Eucalyptus hybrid leaves..
A process for the preparation of vegetable dyes from Eucalyptus hybrid leaves is not hitherto known.
An object of this invention is to propose a process for producing vegetables dyes from Eucalyptus hybrid leaves.
Another object of this invention is to propose a process for the preparation of Eucalyptus hybrid leaves which is simple.
Yet another object of this invention is to propose a process for the preparation of vegetables dyes from Eucalyptus hybrid leaves which has a high yield.
Still another objects of this invention is to propose a process for the preparation of vegetable dyes from Eucalyptus hybrid leaves which can be used on various fabrics such as silk, wool and cotton.

According to this invention there is provided a process for the producing vegetable dyes
from Eucalyptus hybrid leaves which comprises:
i) in crushing the leaf so as to allow an extraction of the dye therefrom;
ii) subjecting the crushed leaves to the step of selective extraction to obtain an
extract of water soluble polyphenoIs; iii) concentrating the extract to obtain said vegetable dye.
In accordance with this invention Eucalyptus hybrid leaves are first crushed and then subjected to the step of selective extraction with water to obtain an extract containing the dye and leaving behind the waxy material.
In accordance with the process of this invention, air dried leaves of Eucalyptus species, such as Eucalyptus hybrid E, trerticornis and E camalduliensis are crushed to mesh 5 in order to rupture the cell walls of the leaves. As known in the art, the leaves have a hard wall and which would thus prevent a generation of the solvent in the absence of causing a rupture of the walls. Thus, in order to afford a higher yield, a crushing of the leaf is essential and whereby a penetration of the solvent is facilitated.

The crushed leaves are thereafter subjected to step of selective extraction by treatment with water and in a material liquor ratio of 1:4 to 1:7 and preferably 1:5. If the ratio is 1:3, the extraction would not be complete as the leaves would themselves absorb water.
The leaves contain essential oil, waxes and chlorophyll. Thus, during the step of selective extraction with water, the water soluble polyphenols get dissolved and the non soluble matter consisting of oil, waxes and chlorophyll are retained in the leaves. If the ratio is 1:8, the mother liquor is too diluted and more energy would be required for concentration.
Such a step of extraction is carried out at a temperature of 90-110°C. The process of extraction is repeated with fresh water solvent but same material to liquor ratio. Each step of extraction is carried out for a period of one hour. If high temperature are employed for the extraction step, it may then lead to the decomposition of polyphenols. Similarly, it has been found that if the period is increased to three hours at a stretch then the extraction may not be complete.

The extraction of the crushed leaves (Mesh 5) can also be carried out at room temperature by keeping the same material to liquor ratio (1:5). The leaves are kept in contact with water for a period, such as 24 hours, and then the extract removed. The process is repeated four time. The combined extract provides the required dye. The yield of dye is slightly lower than in case of the heating process.
The second step involves separation of the water extract from the leaves and washing the residue with the water till it gives no colour.
The combined extract is then concentrated at the temperature of less than 110°C to get the dye. It has been found that if a higher temperature is employed in the step of concentration, then chemical transformation of certain constituents take place and which would detrimentally effect the dyeing value of the end product.
Yield of the dark brown dye obtained by heating process is 28% and that obtained by cold process is 24% and give blue colour with alcoholic ferric chloride.
This dye imparts different shades on silk, wool and cotton by using mordants like alum, ferrous sulphate, chloride etc. which were not obtained earlier.

The dye obtained by the process for the present invention had the following properties:-
1) Form powder
2) Colour brown
3) Odour odourless
4) pH 4.7
5) solubility 9.08g per hour 100ml
6) decomposition Greater than 200°C

I CLAIM:
1 . A process for the producing vegetable dyesf from Eucalyptus hybrid/ leaves
which comprises:
iv) in crushing the leaf^o as to allow an extraction of the dye therefrom;
v) subjecting the crushed leaves to the step of selective extraction^ obtain an

'

extract of water
vi) concentrating the extract to obtain said vegetable
2. A process as claimed in claim 1 wherein said step of extraction consist in adding water to the crushed leaves and which is then heated for allowing a selective extraction of water soluble polyphenols. A process as claimed in claim 2 wherein the ratio of leaves to water is 1:4 to
4. A process as claimed in claim 3 wherein the ratio of leaves to water is 1:5.
A process as claimed in, claim 2 wherein said step of extraction is carried out at a temperature of 90/to 110°C and for a period of one hour.

6. A process as claimed in claim 1 wherein said leaves are crushed to a size of
mesh 5.
7. A process for producing vegetable dyes from Eucalyptus hybrid leaves
substantially as herein described.