CARDANOL FROM C.N.S.L. OIL (CASHEWNUT SHELL LIQUID)

Cardanol oil, a renewable raw material well known by product of the cashew industry, has been used as the starting material for the synthesis of novel fulleropyrrolidines cardanol based. In this work, cardanol has been used as building block for the preparation of target cardanol based precursors obtained by the way of the convenient transformation of the functional groups (aromatic ring, -OH group or the double bonds of the side chain) of the cardanolic structure. Pure 3-n-pentadecylphenol and its derivatives having homogeneous chemical composition, used as the precursor of any fulleropyrrolidines, have been prepared by hydrogenation of the un-saturated side chain and subsequent alkylation of the aromatic ring of cardanol. The reactivity of olefinic double bond present in the side-chain which can undergo easy transformation i.e. oxirane formation as well as metathesis reactions affording various interesting fulleropyrrolidines is also described.

Cashew nut shell liquid or oil obtained by heat treatment contains about 10% cardol and about 90% cardanol (a vessicant oil liquid) resulting from decarboxylating anacordic acid and its polymers. Formerly, a moister product of the cashew kernel industry in southern India, Cashew nut shell oil has become a valuable raw material in the manufacture of many industrial product. It condenses with formaldehyde and other chemicals into resin that can be used in many unique combination for the manufacture of brake lining, clutch and other friction facings, insulating and water proofing varnishes and coating laminating resins, molding composition oil & acid proof cement & industrial floor tile, type writer rolls and myriad other products, varnishes made with these resin are resistant to acid and alkalies and possess unusual resistance to the softening action of mineral oil; they are used to coat paper for bottle cap liners and for many other water proofing and insulating purposes.

The polymerized liquid is used as a potting compound for magnetoelectric machine armatures in air planes because of its high heat resistance subsequent treatment of the polymerized product with formaldehyde, trioxymethylene, paraformaldehyde or furfuraldehyde at room temperature for 24-72 h produced a substantially infusible solid resin that retains high binding power at elevated temperature without softening hydrogenation of the phenol in the oil produced many useful products such as a cosolvent for rotovore in the preparation of insecticides. The hydrogenaled oil has none of the vesicant action of the original liquid cashew nut shell oil also is used in India for protecting wood and paper against termites and for motor roofing and preserving fish nets, textiles and lumber.

The cashew nut shell liquid (CNSL) is a byproduct & the cashew nut processing industry cashew nut trees are found in Kamataka, Kerela and Tamil Nadu, Maharashtra etc. About 60,000 tons of nuts are collected annually for processing into kernels; and in addition 50,000 tons and received from East Africa. Oil is extracted from 1/3 rd of the available nuts.

Almost all the cashew processing factories are in the small scale sector. These units adopt either the Drum Roasting Method & nut-oil Butts Process while processing cashew nuts. It is reported that raw cashewnuts contain over 20% oil in the shells. In the old Drum Roasting Process, such if the oil gets burnt during roasting where as in the oil-Bath process about 10% good quality shell oil can be recovered from the oil in the process itself as a by-product. This oil is of good quality and finds ready market. The shell still contains 10 to 12 percent oil which can be recovered either by solvent extraction or by using expellers.

Cashew nut shell liquid is a versatile raw material. The potential availability by CNSL is estimated at 40,000 tons but the actual average production is only by the order by 9,000 tons, primarily due to look of market.

The industrial application & CNSL are based open its polymerization to a rubber like material under the influence by acids and on the formation of a wide range of condensation products with aldehydes.

CNSL resins are resistant to acids alcohols and constic alkalis and give filing which retain flexibility even after booking. Baked filings are resistant to solvents and abrasion.

Historical Background

Cashew (Anacardium occidentale L.) a native of Eastern Brazil introduced to India just as other commercial crops like Rubber, Coffee, Tea etc. by the Portuguese nearly five centuries back. The first introduction of cashew in India was made in Goa from where it spread to other parts of the country. In the beginning it was mainly considered as a crop for afforestation and soil binding to check erosions. The nuts, apple and other by products of this crop are of commercial importance. Though its commercial exploitation began from the early 60’s, marginal lands and denuded forests were the areas set apart for the plantation development. Due to the absence of high yielding varieties and multiplication techniques, indiscript seeds and seedlings were used for planting purposes. Because of its adaptive ability in wide range of agro climatic conditions it has become a crop of high economy and attained the status of an export oriented commodity bringing considerable foreign exchange to the country.

Cashew (botanical name Anacardium occidental) was introduced in India by the Portuguese four centuries ago, mainly to prevent soil erosion. Cashew ranks second among the nine treenuts which figure prominently in international trade circles, first being almond. The cashew adapts to various types of soils and climatic conditions and is hardy and draught resistant tree.

For several centuries the cashew trees was considered merely as a sturdy perennial tree which yielded soft wood and bore the delicious juicy cashew apple. The peculiarity of the cashew apple is that it has nut outside. In the earlier days, the nut was thrown away after the apple was eaten. The nut was rejected since it has a hard shell cover which contains a corrosive liquid (cashewnut shell liquid) which burns the skin on contact. As time passed, interest developed in the nut and various methods of extracting the kernel from the nut proved successful.

Cashew nut has been cultivated in several countries for a long time but the credit for launching into commercial production and export of cashew kernels goes to India. Very small quantities of unpeeled cashew kernels were exported to Marseilles and london, in the beginning of the present century. Since then exports have shot up tremendously and 50-56 thousand tons of cashew kernels were exported during the decade ending 1973-74. The export of cashew kernels in the period 1946-78. Grew at the rate of 4.1% per annum, as compared to the 5.2% annual growth rate of world export.

The cashew is chiefly growth in the coastal districts of India and nearly 70 percent of the production is from the West Coast between Mumbai and Cape Camerin. Ratangiri and North Kanara districts in Mumbai. South Kanara, Malabar, Tiruchirapalli, Tanpore and South Arcot districts in TamilNadu state, Nellore, Godavari and Vishakhpatnam districts in Andhra, and Travancore-Cochin are major areas of production. Nearly 50% of the production comes from Tamil nadu state, while Travancore Cochin State accounts for about 36 percent and Bombay 10 percent. West Bengal, Orissa, Karnataka and Andhra Pradesh are other states in India which together accounts for about 4.0 percent of the product.