Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group ib metal
Reexamination Certificate
2001-03-20
2003-07-22
Bos, Steven (Department: 1754)
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group ib metal
C423S043000, C423S604000, C423S140000, C423S142000
Reexamination Certificate
active
06596246
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention pertains to highly stable cupric hydroxide compounds obtained by removing iron impurities from the starting copper solution.
2. Description of the Related Art
Stable copper hydroxide is a product that is difficult to obtain, even when employing a highly purified copper salt as a starting material. This is because even small amounts of ferrous (Fe
II
) impurities can catalyze the decomposition of cupric hydroxide to cupric oxide:
Thus, a spray application of ppm Fe
II
ion can catalyze the dehydration of Cu(OH)
2
to CuO.
However, the production of Cu(OH)
2
requires starting materials that are very low in iron content. These materials are both difficult to find and are expensive, because ferrous ion is very widely distributed in any starting material. As a result, there is a need to rapidly and efficiently remove ferrous ions from the raw materials used in cupric hydroxide production.
Copper compounds, including copper hydroxide, are used to treat plant fungi. Pathogenic fungi cause a substantial reduction in expected crop yields. Further losses result from fungi during the storage of harvested crops. Although there are over 100,000 known species of fungi, no more than 200 are known to cause serious plant disease.
The classes of fungi associated with important diseases in plant crops include Phycomycetes, Asomycetes, Basidiomycetes and Deuteromycetes. Examples of Phycomycetes include Phytophthora infestans (potato late blight) and Plasmopara viticola (downy mildew of grape). Examples of Ascomycetes include
Erysiphe graminis
(powdery mildew of wheat/barley),
Podosphaera leucotricha
(apple powdery mildew) and
Pyricularia oryzae
(rice blast). Examples of Basidiomycetes include Puccinia spp. (leaf rust of wheat and oats), Rhizoctonia spp. (sheath blight of rice) and Ustiliago spp. (corn smut). Examples of Deuteromycetes include Alternaria spp. (tobacco brown spot), Botrytis spp. (gray mold of grape), Cercospora spp. (leaf spot of sugar beet), Fusarium spp. (wheat blight), Helminthosporium spp. (leaf spot of corn),
Pseudocercosporella herpotrichoides
(eyespot of wheat),
Septoria nodorum
(blotch of wheat) and
Septoria tritici
(wheat leaf blotch).
The fungicides can be classified into systemic and nonsystemic fungicides. The systemic fungicides can penetrate the seed or plant and are then redistributed within to unsprayed parts or subsequent new growth, rendering protection from fungal attack or eradicating a fungus already present. The nonsystemic fungicides have a protectant mode of action and must be applied to the surface of plant generally before infection takes place. The inorganic salts are generally classified as nonsystemic fungicides.
The use of copper as a fungicide is well known. Copper sulfate was used from treating the seed-borne disease wheat bunt (Tilletia spp.) as early as the eighteenth century. In 1882, it was observed that grapevines that had been coated with a mixture of copper sulfate and lime to deter grape pilferage were not infected with grape downy mildew (
Plasmopara viticola
). This observation resulted in the development of a fungicide called Bordeaux mixture. Copper fungicides currently available for a wide variety of applications include the hydroxides, sulfates (Bordeaux mixture), oxides and oxychlorides and a variety of organic salts such as copper naphthenates and copper quinolinates. Crops protected using copper compounds include vines, fruit, coffee, cocoa and vegetables. Most copper fungicides work by inhibiting fungal spore germination. Sensitive fungi are affected by the uptake of copper salts and its subsequent accumulation, which then complexes with amino, sulfhydryl, hydroxyl or carboxy groups of enzymes resulting in the inactivation of the fungus. Fungicides are discussed in the
Kirk-Othmer Encyclopedia of Chemical Technology,
4
th
Ed. (1994), Volume 12 at pages 204-227.
Copper compounds are also effective against bacterial plant diseases. A common bacterial plant disease amenable to treatment by copper compounds, including cupric hydroxide, is citrus canker. When environmental conditions are favorable for the spread of the disease, chemical control measures are not entirely effective. However, materials containing copper (Bordeaux mixture, copper hydroxide, basic copper chloride, copper oxychloride, and tribasic copper sulfate) are the most effective bacterial sprays for protecting leaves and fruit. These materials can reduce the incidence of disease, but they will not eliminate established infections. Extensive use of copper may also cause phytotoxicity problems in treated groves.
Copper hydroxide is also used to treat tomato bacterial spot (
Xanthomonas campestris
pv.
vesicatoria
). Copper hydroxide is applied at the first sign of disease and repeated at 10- to 14-day intervals when warm, moist conditions prevail. Copper is strictly a protectant and must be applied before an infection period occurs. Coverage is 4 lb of copper hydroxide per acre.
The most common copper fungicide incorporating copper hyhdroxide is Bordeaux mixture (CuSO
4
&OHgr;3Cu(OH)
2
&OHgr;3CaSO
4
). The standard formula for Bordeaux mixture is four pounds of copper sulfate, four pounds of hydrated lime and 50 gallons of water. Mix four pounds of the lime in four gallons of water. Do the same for the copper sulfate. Strain the lime mixture through cheesecloth, add to 42 gallons of water, and then add the sulfate mixture. Use immediately. Small amounts can be made by mixing four ounces of hydrated lime in 2 gallons of water. Mix four ounces of copper sulfate in 1 gallon of water. Pour the copper sulfate mixture into the lime mixture. Bordeaux mixture can cause damage to plants if used improperly. Damage or injury results more in humid weather and when the mixture doesn't dry quickly. Bordeaux mixture will leave a bluish-white deposit on the plant.
Once made, Bordeaux mixture is not stable. Poorly stirred Bordeaux mixture has little value as the active copper compound is not sufficiently finely divided. Other materials are frequently added to Bordeaux mixture in order to increase the stability. If other materials are to be used in the mixture, they may then be added with further agitation. White oil may be used at around 500 mL/100 L of spray or similar amounts of calcium caseinate (500 g/100 L) or molasses (500 mL/100 L). White oil or summer spraying oil may be used at the rate of 500 mL/100 L spray to enhance penetration of the spray under bud scales. Similarly calcium caseinate and molasses have been recommended from time to time for various crops. These are reported to improve the weathering ability of the spray by producing a surface layer on tile leaves which protects the copper particles from being dislodged by rain or irrigation.
Fungicides such as Bordeaux mixture are also characterized by sticking poorly to the plant. The sticking ability of Bordeaux mixture can also be improved by the addition of polymers. However, polymer additives tend to be expensive.
For Burgundy mixture, the slaked lime is replaced by the fully soluble washing soda (sodium carbonate). In other respects, the procedure is the same and the end results are similar although the mixture is said to stick better than Bordeaux but is also more likely to burn sensitive foliage. The main advantage of Burgundy mixture is the ease of use of the washing soda compared with slaked lime. Fresh soda should be used; old material may have less water of crystallization and it is difficult to judge the amount required.
To make an equivalent Burgundy mixture to that described above for Bordeaux, replace the 1 kg of slaked lime with 1.5 kg of washing soda. If the normally crystalline washing soda appears white and powdery, use only 1 kg and then check the made-up mixture for pH before use.
Although the conventional art recognizes the applicability of copper compounds as a fungicide, the conventional art also recognizes that the copper fungicides have disadvantages that need to be rectified. Typical of the conventional art
Huato Julio
Ogura Tetsuya
Bos Steven
Dermet SA de CV
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