|Title of Invention||
A PROCESS FOR PREPARING ANTI-FUNGAL ANIT-WOOD BORER AND ANTI-TERMITE COMPOSITIONS FOR TREATING WOOD
|Abstract||1. A process for preparing anti-fungal anti-wood borer and anti-termite compositions for treating wood from by-products formed during nitration of toluene comprising the steps of acidification of the aqueous waste stream -"black liquor"- generated in the nitration of toluene with acid to recover the dissolved nitrocresols and structurally similar compounds in the form of total precipitated solids and redissolving the total precipitated solids either in water with caustic lye or in a suitable solvent to get water based and solvent based compositions respectively.|
|Full Text||FORM 2
THE PATENTS ACT , 1970
(See Section 10) Rule 13
A PROCESS FOR PREPARING ANTI-FUNGAL ANTI-WOOD BORER AND ANTI-TERMITE COMPOSITIONS FOR TREATING WOOD
Mr. Ajay Chimanlal Mehta of Mumbai Jndian Inhabitant residing at Kejriwal House ,7-N Gamadia Road, Near Jaslok Hospital , Mumbai- 400 026 .Maharashtra State , India,
The following specification particularly describes the nature of this invention and the manner in which it is to be performed :-
Original 18-5-2004 8 may 2004
This invention relates to a process for preparing anti-fungal anti-wood borer and anti-termite compositions for treating wood using by-products formed during the nitration of Toluene.
The commonly used anti-fungal protective chemicals for the treatment of wood are phenolics (2,4- and 2,6-dinitrophenoI) , compounds of Boron ,Copper, Chromium , Zinc , Nickel, and Arsenic , Coal Tar Creosote , Benzene Hexachloride , Dieldrin , DDT and less commonly fungicides like Mancozeb. The different compounds of heavy metal that are used are Copper Arsenate , Copper Chromate , Copper Fluoroborate , Copper Nitrate, Copper Oxide, Copper Sulfate , Copper Naphthenate , Nickel Sulfate , Phenylmercuric Naphthenate , Arsenic Pentoxide , Boric Acid , Borax and Sodium Fluoride. The anti-fungal chemical in the form of aqueous solution or solvent based formulation is normally applied to the wood surface either by spraying , dipping or as primer coating prior to its use. The presence of the anti-fungal coat on the wood surface protects it from the fungal attack under conditions of high humidity / moisture by inhibiting the germination and growth of fungal spores that are naturally present in the air or on the wood surface. In the absence of any such protective anti¬fungal coating , the decay fungi breakdown the various components of wood enzymatically to forms that they readily assimilate. Such wood is said to be decayed or rotted and it loses its desirable properties of strength and structure.
The conventional anti-fungal wood preservatives are based on heavy metals, coal tar derivatives , some pesticides and pentachlorophenol and although some of them are highly effective in protecting the treated wood from fungal decay and spoilage , these products have some drawbacks. Metals such as copper, chromium , arsenic , nickel, etc. are not suitable because of their high toxicity and persistence in the environment. Pesticides such as Dieldrin , DDT , etc. are less effective in providing long term protection and they are being phased out because of their high human toxicity. Use of Pentachlorophenol has been banned in leather industry and its use is being phased out in wood industry because of its high toxicity, mutagenicity and persistence in
environment. In view of this there is a need for developing an anti-fungal wood preservative free of heavy metals, having low toxicity, no mutagenicity and biodegradable in nature. The above desirable properties along with high anti-fungal activity are present in the compositions based on total precipitated solids, which distinguish it from the conventional anti-fungal wood preservatives.
During the nitration of Toluene using mixed acid, a waste aqueous stream hitherto referred to as 'Black Liquor' is formed. Toluene is nitrated using a mixture of concentrated sulfuric and nitric acids under specified conditions of temperature and time and after the reaction yielding a mixture of mono-nitro derivatives of toluene such as o-, p- and m-nitrotoluene is complete, the organic phase and aqueous phase are physically separated. The organic phase is then washed with alkali to remove the traces of acid and these alkali washings are collectively referred to as black liquor because of its dark reddish-brown to almost black colour. The black liquor contains by-products (mono- ,di- and tri-nitrocresols, p-nitrophenol, 2,4-dinitrophenol and 3-nitro ,4-hydroxy benzoic acid) formed because of certain side reactions during nitration of toluene and these by-products being soluble in alkali they get extracted into the alkali washings and end up as a waste aqueous stream. This black liquor generated during alkali washing of nitration mixture , is deep red in colour, with a high COD (Chemical Oxygen Demand) of 29,000 mg/l to 30,000 mg/1 and as per published scientific literature it is reported to consist of a mixture of mono-, di- and tri-nitrocresols , p-nitrophenol , 2,4-dinitrophenol and 3-nitro , 4-hydroxy benzoic acid. These solids are precipitated out from the black liquor by adjusting its pH in the range 6.0 to O.O.These are hitherto referred to as 'total precipitated solids'. The process described herein for use of total precipitated solids from the black liquor for the preparation of anti-fungal compositions employs acids such as sulfuric acid, hydrochloric acid for precipitation and water , caustic lye and solvents for the preparation of compositions.
The method commonly employed for the disposal of black liquor is incineration , however , considerable value addition is achieved by isolating and formulating the total precipitated solids with simultaneous reduction in COD to around 2000 mg/1. The precipitation was carried out by adjusting the pH of the black liquor between 6.0 to 0.0 by addition of concentrated mineral acid such as Hydrochloric acid , Sulfuric acid at room temperature. The precipitation was complete in 30 minutes to 60 minutes , the slurry of total precipitated solids was chilled to a temperature ranging from 5°C to 15°C and filtered to get a wet cake of total precipitated solids (dark yellow in colour), which was then dried at a temperature of 30°C to 40°C to yield dry solid.
High Pressure Liquid Chromatograph (HPLC) analysis of the total precipitated solids revealed 4,6-Dinitro-o-cresol and an unidentified component ( major) and Thin Layer Chromatograph analysis (TLC) revealed (solvent system chloroform : methanol : water : 20 ml: 5 ml :3 drops) presence of at least 6 compounds of which 4,6 Dinitro-o-cresol and 2,4,6-trinitro-m-cresol were identified by comparison with known standards. Further identification of compounds was difficult because of non¬availability of standards. The total precipitated solids has a melting point in the range 66°C to 75°C , is soluble in solvents like methanol, ethanol and mixed xylene and sparingly soluble in water.
The total precipitated solids recovered as above were used to prepare two types of anti-fungal compositions , viz. aqueous and solvent based. Aqueous, composition consisted of a 2 % w/v solution of the total precipitated solids in water as a sodium salt ( pH of 5.5 to 6.0) and was prepared by dissolving the total precipitated solids in water by addition of caustic lye. Solvent based composition was prepared by dissolving the total precipitated solids in a solvent such as mixed xylene , turpentine , Aromax, Solvent C9 and mineral turpentine oil to give a 2 % w/v solution.
Assay methods to evaluate the anti-fungal activity of total precipitated solids vis-a¬vis known anti-fungal chemicals , 2,4- and 2,6-dinitrophenol mixture and pentachlorophenol (PCP), were standardised as follows:
a. Growth inhibition test
The activity of the sodium salt of the total precipitated solids was tested against nine fungal cultures (cultures not identified) obtained in pure from decaying wood, soil and air. The sodium salt of the total precipitated solids was incorporated into the sterile molten medium (YEMA - Yeast Extract Malt Extract Agar ) at predetermined concentrations and after solidification of the agar medium , the plate was inoculated with a spore suspension of the test culture and incubated at room temperature. The plates were checked for growth at 24 h intervals for 8 to 10 days and growth inhibition pattern for total precipitated solids and dinitrophenol (sodium salt) was recorded.
Total precipitated solids (in the form of sodium salt) at the concentration of 100 ppm to 400 ppm allowed good growth with sporulation , at 500 to 900 ppm there was poor growth with sporulation and at 1000 ppm scanty or no growth and no sporulation of all the cultures mentioned above,which were not identified were tested.
Dinitrophenol (in the form of sodium salt) at the concentration of 100 to 200 ppm allowed good growth with sporulation, at 300 ppm there was scanty or no growth and no sporulation of all the fungal cultures tested as mentioned above,which were not identified ,were tested. Pentachlorophenol (in the form of sodium salt) at 100 ppm inhibited growth of eight out of nine cultures tested and at 500 ppm growth of all nine cultures was inhibited.
The anti-fungal activity of the total precipitated solids was more pronounced under acidic conditions than alkaline conditions.
b. Application test.
To arrive at the practical minimum inhibitory concentration of the total precipitated solids against fungal infection on wood and to assess the anti-fungal protection offered, clean wood chips (free of fungal infection ) were treated with different concentrations of the anti-fungal chemical by dipping in the solution for a fixed period of time (30 minutes) , air dried and inoculated with the test culture. The inoculated wood chips were incubated in sterile Petri dishes in a humid atmosphere and checked for fungal spoilage. An untreated and uninoculated wood chip along with an untreated but inoculated wood chip served as controls. The growth inhibition pattern for total precipitated solids, dinitrophenol and pentachlorophenol was recorded.
All untreated but inoculated wood chips showed good fungal growth and spoilage. The treated but uninoculated wood chips showed no fungal growth and spoilage. Total precipitated solids (aqueous solution of sodium salt, pH 3.0 to 5.0 ) at 1000 ppm to 2000 ppm concentration permitted poor growth of five out of nine cultures tested and at 2500 ppm growth of all cultures was inhibited.
Dinitrophenol and pentachlorophenol (aqueous solution of sodium salt) at 1000 ppm concentration showed total inhibition of fungal growth on wood chips. Total precipitated solids (composition prepared in mixed xylene) at 1000 ppm to 2000 ppm concentration permitted poor growth of some cultures , at 2500 ppm to 5000 ppm no significant growth of any culture was observed and at 5000 ppm to 10,000 ppm total growth inhibition of all cultures was observed.
Similar results were obtained with methanolic solution of the total precipitated solids. From the application tests it was concluded that the total precipitated solids offered good protection to wood against fungal attack and spoilage at a concentration above
10,000 ppm and its anti-fungal activity was approximately half that of the well known anti-fungal chemical pentachlorophenol at the same concentration . Based on the above results, it was decided to prepare anti-fungal compositions containing 2 % w/v of total precipitated solids for optimum anti-fungal activity in actual use for wood and timber, as a higher concentration is always better for practical application.
The aqueous and solvent based compositions prepared were found to be very effective in arresting fungal spoilage of wood as determined in application tests. The solvent based composition was compared in its effectiveness with other solvent based wood preservatives available on the market. Total precipitated solids composition of this invention and one of the conventional available formulations in the market inhibited growth of all nine cultures tested, whereas the other two conventionally available could inhibit only six out of the nine cultures tested. The total precipitated solids composition was comparable to one of the brands tested in its efficacy in preventing fungal spoilage of wood and superior to the other two formulations.
The aqueous and solvent based compositions prepared from the total precipitated solids were also tested on wood chips which were exposed to humid atmosphere to check for spoilage due to airborne fungal spores. However, no spoilage was observed even after a period of 2 to 3 weeks.
The major advantages offered by the total precipitated solids based compositions as against conventional anti-fungal wood preservatives are , they are PCP-free and do not contain toxic elements like copper, chromium and arsenic.
This invention will now be illustrated in greater detail with reference to the following examples, but it should be understood that the present invention is not limited thereto.
To a beaker equipped with a stirrer and thermometer ,1000 ml sample of 'black liquor' (aqueous waste stream containing nitrocresols and structurally similar compounds and which is generated during nitration of toluene using mixed acid) was charged and concentrated sulfuric acid (11.6 g , 98 % strength) added dropwise under stirring. The resultant mixture was stirred for 30 minutes to complete the precipitation at a pH between 1.8 to 2.0. The contents of the beaker were then chilled to 15°C and the slurry of total precipitated solids was filtered and wet cake dried at 35°C to yield about 26.18 g of total precipitated solids.
Aqueous composition - To a beaker equipped with a stirrer , 900 ml water and 20 g total precipitated solids was charged successively and caustic lye (12.3 g, 47 % w/w) added dropwise to dissolve the total precipitated solids completely under stirring for 30 minutes.
The volume was made up to 1000 ml by addition of water and the solution filtered to remove extraneous matter and its pH adjusted to 5,50 to 5,70 with concentrated sulfuric acid. Solvent based composition - To a beaker equipped with a stirrer, 950 ml solvent ( a mixture of 930 ml turpentine and 20 ml mixed xylene) and 22 g total precipitated solids was charged successively and the mixture was stirred for 1 h to dissolve the total precipitated solids. The volume was made to 1000 ml by adding turpentine and filtered to remove insolubles (1 to 2 g).
Total precipitated solids obtained as shown in Example 01 were used for preparing solvent based composition with the same set up as shown in Example 01 using Solvent C9 (1000ml) in place of turpentine and mixed xylene as solvent.
Total precipitated solids obtained as shown in Example 01 were used for preparing solvent based composition with the same set up a shown in Example 01 using Aromax (1000 ml) in place of turpentine and mixed xylene as solvent.
Total precipitated solids obtained as shown in example 01 were used for preparing solvent based composition with the same set up as shown in Example 01 using Mineral Turpentine Oil (1000 ml) in place of turpentine and mixed xylene as solvent.
Total precipitated solids obtained as shown in Example 01 were used for preparing solvent based composition with the same set up as shown in Example 01 using methanol (1000 ml) in place of turpentine and mixed as solvent.
While the invention has been described in detail and with reference to the specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
1. A process for preparing anti-fungal anti-wood borer and anti-termite compositions for treating wood from by-products formed during nitration of toluene comprising the steps of acidification of the aqueous waste stream -"black liquor"- generated in the nitration of toluene with acid to recover the dissolved nitrocresols and structurally similar compounds in the form of total precipitated solids and redissolving the total precipitated solids either in water with caustic lye or in a suitable solvent to get water based and solvent based compositions respectively.
2. A process for preparing anti-fungal anti-wood borer and anti-termite compositions for treating wood as claimed in claim 1 ,wherein the acid is sulfuric acid or spent acid of a composition with sulfuric acid 50 to 70 % and nitric acid 0.1 to 5.0 % and remaining water is used to recover the dissolved nitrocresols and structurally similar compounds in the form of total precipitated solids from the black liquor.
3. A process for preparing anti-fungal anti-wood borer and anti-termite compositions for treating wood as claimed in claims 1 and 2, wherein the total precipitated solids recovered as above are dissolved in water and caustic lye under stirring to obtain an aqueous composition having a pH of 5.0 to 7.0
4. A process for preparing anti-fiingal anti-wood borer and anti-termite compositions for treating wood as claimed in claims 1,2 and 3, wherein the total precipitated solids recovered as above are dissolved in a solvent like turpentine containing upto 2 % v/v mixed xylene to obtain solvent based composition.
5. A process for preparing anti-fungal anti-wood borer and anti-termite compositions for treating wood as claimed in claims 1, 2, 3 and 4, wherein suitable solvent such as Solvent C9 and/or Aromax, a fraction from petroleum refining, may be used in preparation of solvent based composition.
6. A process for preparing anti-fungal anti-wood borer and anti-termite compositions for treating wood as claimed in claims 1, 4 and 5, wherein Mineral Turpentine Oil may be used in preparation of solvent based composition.
7. A process for preparing anti-fungal anti-wood borer and anti-termite compositions for treating wood as claimed in claims 1, 4, 5 and 6, wherein methanol may be used in preparation of solvent based composition.
Dated this 11th August, 2000
(B.S.SHAH) Duly Constituted Attorney
|Indian Patent Application Number||862/MUM/2000|
|PG Journal Number||41/2007|
|Date of Filing||19-Sep-2000|
|Name of Patentee||AJAY CHIMANLAL MEHTA|
|Applicant Address||KEJRIWAL HOUSE, 7-N GAMADIA ROAD, MUMBAI-400 26.|
|PCT International Classification Number||N/A|
|PCT International Application Number||N/A|
|PCT International Filing date|