Title of Invention

"A PROCESS FOR THE PREPARATION OF A CHIRAL FIBER MATERIAL FOR EM WAVE ATTENUATION"

Abstract

The present invention is for the preparation of a chral fiber material for EM wave attenuation. A chiral material is first synthesized by condensing an acid chloride with an chiral amine compound in presence of an alkali. The reaction mixture thus obtained is then poured in distilled water and is filtered to obtain the chiral material as a cream coloured mass. The said mass is then dried. Dissolving the dried mass in a solvent mixture and allowing the solution to crystallize at a temperature of 4-30°C for 16 to 48 hours to obtain the chiral fiber material. The length and diameter of the chiral fiber is 1-4 cm and 25-10µm respectively. The Chiral fiber material obtained has a helical confirmation.

Full Text

The field of invention relates to the process for preparation of a chiral fiber material. The present invention describes the preparation of a chiral fiber material for use in electromagnetic wave attenuation. BACKGROUND OF THE INVENTION Chiral materials are now well known and they display handed structure in the same way as our own left and right hand. Each frequency of linearly polarized light is rotated by a different amount during transmission through a chiral medium. This phenomenon is known as optical activity and is observed by measuring optical rotation. In 1895, Cotton showed that chiral media can transform a linearly polarized wave into an elliptically polarized wave. The well known phenomenon of optical rotation and dichroism is observed in certain molecules and macromolecules. Most naturally occurring molecules and polymers such as nucleic acids, proteins and polysaccharides are chiral and optically active. Both naturally occurring and synthetic chiral polymers have attracted the attention of polymer scientist because of their application in many fields of science and technology including chemistry, biology, pharmacy, medicine, environmental science and optoelectronics. The application of chiral polymers reported in the patent literature includes matrix for chiral chromatography and chiral inducer in regioselective catalyst, as a chiral stationary phase in enantiomeric separation, as active and passive optical element, non-linear optics and optical information storage as in the fabrication of optoelectronics devices and as polarizing coatings or as polarized lenses, for asymmetric synthesis etc. a chiral polymer selected from polyphosphazeness was used as an infrared radiation blocking material in a thermal insulation product. The present invention is for the synthesis of chiral fiber materials to be used for new application, i.e., for EM wave attenuation. Several studies have theoretically examined specular light reflection and refraction for chiral media. The possibility of controlling the propagation characteristics of EM waves by varying the chirality parameter has been predicted by several theoretical modeling of chiral composite. The chirality in a material not only affects the polarization of wave propagation but also affects reflection, transmission and attenuation characteristics as well. Earlier chiral properties were achieved by incorporating metal helices in a matrix medium and EM wave propagation studies were extensively carried out by researchers. Inherent demerits of such chiral materials are their physical realization for any specific application due to their weight, poor chemical resistance and integrity with the host materials. To overcome such problems coliled carbon fibers and carbon microcoils were subsequently synthesized and used for similar application. Further, carbon fibers are will known filler elements for EM wave absorption and scattering over a broadband frequency region. Now attempts have been made to synthesize chiral organic/polymer materials for this purpose. The added advantages of organic chiral material over conventional material are its structural integrity with the host matrix and high performance in terms of band width and ultra light weight features. Development of organic chiral materials in the form of fibers and their demonstration for EM wave attenuation have not been reported so far in patent literature and this is a real challenge today. Chiral material and its fiber of desired length have been prepared. The present invention is therefore first of its kind and is associated for synthesizing chiral fiber materials for EM wave attenuation. OBJECTS OF THE INVENTION The main object of this invention is preparation of a chiral fiber material to be used for high performance EM wave attenuation. Another object of this invention is to synthesis a chiral compound. Yet another object of this invention is to obtain such chiral material in fiber form. SUMMARY OF THE INVENTION According to this invention the condensation reaction of a chiral amine compound and a saturated or ethylenically unsaturated acid chloride in appropriate ratio in the presence of a base compound or alkali has provided a chiral compound. To carry out such a reaction a three necked flask is required along with an ice bath and does not need any sophisticated reactor. The process is versatile and used for making chiral material. The byproduct, hydrochloric acid in the presence of a base compound or alkali is neutralized and washed out with water only. The next step is the formation of fiber of the chiral compound. It is obtained by recrystallization process for which only a beaker and a proper selection of solvents are required. DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a chiral material is synthesized by the condensation reaction of an acid chloride with a chiral amine compound in an appropriate ratio in the presence of a base. The byproduct, which is hydrochloric acid, is neutralized by the base compound and thus the reaction is facilitated. Then the synthesized chiral compound is allowed for crystal growth in an appropriate solvent mixture at a temperature of-10 to 30°C for 16-48 hrs. Thus a long fiber like crystal of the chiral material is obtained, which is having 1-4 cm length and diameter 25-100µm respectively. The aspect ratio of the crystal fiber is 200-1600. The fiber like crystal of chiral material what we call as chiral fiber. The reaction involved in the synthesis of chiral material is shown below: (Formula Removed) R=-CH3, -C2H5, -C6H5, -CH=CH2, -C(Me)=CH2, isobutyryl R1=alkyl group (C1-C8) Ar=Ph, Substituted phenyl, naphthyl According to the present invention, the process of the preparation of chiral material in fiber form comprises of the following steps. 1. Synthesis Of Chiral Material A chiral material is synthesized by the condensation reaction of a saturated or unsaturated or aromatic acid chloride with a chiral amine compound in an appropriate ratio in the presence of alkali or a base compound. The chiral amine compound, is taken in a three necked flask along with an alcohol solvent and the base compound or alkali solution and the flask was kept in an ice bath. The appropriate quantity of acid chloride is then added dropwise through a dropping funnel fitted in the side arm of the flask during 45-120 min while stirring the reaction mixture. The reaction was then allowed to carry out for 12-30 hrs at 0.4°C. The reaction by product, hydrochloric acid is neutralized by the base compound or the alkali, which facilitates the reaction. The reaction mixture was then poured in a large excess of distilled water contained in a beaker. The precipitate was filtered and then washed repeatedly with distilled water to remove the byproducts. The chiral material is obtained as cream colored mass. It is then dried at 60°. The yield of chiral material is ~ 88-90%. The acid chloride is selected from the following compounds: acetyl chloride (purity: 98%) acryloyl chloride (purity:98%) tert-butylacetyl chloride (purity:99%) isobutyryl chloride (purity:98%) benzoyl chloride (purity:99) methacryloyl chloride (purity:97%) 1-nathphoyl chloride (purity:98%) 2-nathphoyl chloride (purity:98%) The chiral amine compound is selected from the following: D-(+)-oc-alkyl aryl amine (alkyl:C1-C4) (purity:99%) L-(-)--alkyl aryl amine (alkyl: C1-C4) (purity:99%) L-valine (purity :99%) L-leucine(purity:99%) R-(+)-l-(l-naphthyl) alkyl amine (alkyl: C1-C4) (purity:98%) S-(-)-l-(l-naphthyl) alkyl amine (alkyl: C1-C4) (purity:98%) and the alkali or base compound used here is either NaOH (purity:97%), KOH (purity: 85%) solution 30-60% or triethyl amine (purity:99.7%). The organic solvent used for synthesizing chiral compound is either methanol (reagent ACS, 99.8%), ethanol (reagent), iso-propanol (anhydrous, 99.8%), and n-butanol (99%), sec-butanol(99%), chloroform (stabilized, 99%), or a mixture of two. 2. Preparation of Chiral Fiber Material The chiral material synthesized above was crystallized from an appropriate solvent mixture till the crystals are formed. The temperature is kept between 4 to 30°C and time between 16 to 48 hrs. for crystallization. Initially, the synthesized chiral material is dissolved in the solvent mixture under slightly warm condition. Then it is allowed for crystallization keeping without disturbance. Thus a long fiber like colorless crystal of chiral material is obtained (FIG.l). The solvent used for crystallization of chiral material is selected any two from the following: methanol (reagent ACS, 99.8%), ethanol (reagent), iso-propanol (anhydrous, 99.8), and n-butanol (99%), seobutanol (99%), chloroform (stabilized, 99%) and distilled water. The yield of chiral fiber material is -80-82%>. Melting point of the material is 70-160°. The material is characterized by the instrumental techniques for chemical analysis. The elemental analysis result shows that the material contains: %C=55-80,% N=5-15,%H=7-12, %0=10-25.IR results (v,cm-l) ; 3726, 3447, 3334, 3059, 3033, 2975, 2928, 2869, 2729, 1950, 1727, 1650, 1615, 1520, 1448, 1370, 1326, 1250, 1220, 1125, 1024, 856, 758, 700, 661, 609, 557, 531.'H-NMR (CDC13, TMS, 8) results 8.34, 7.77, 7.64, 7.52, 7.21, 5.05, 4.08, 1.58, 1.38. The length and diameter of such fibers are 1.4 cm and 25-100 um respectively (FIG.2). The value of [ ] 25 D for the chiral fiber material is + 15 to + 79° or-19 to -86° (c=l, DMF). The result of secondary structure estimation of the chiral fiber material is given below. (Table Removed) In the present invention, chiral fibers exhibit optical rotation at 589 nm wave length and they have helical conformation. The fiber materials have the advantage of scattering effect on EM waves and they have the utility in the development of coatings for EM wave attenuation. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig.l :Chiral Fibers (a and b) obtained by the recrystallization process Fig.2 Scanning electron micrographs (a and b) of chiral fibers DETAILED DESCRIPTION OF THE DRAWINGS The Fig 1 shows the chiral fibers obtained by the recrystallization process. The chiral material obtained after crystallization are long fiber(l) like colourless crystal of chiral material. The Fig 2 shows the scanned electron micrograph structure of the fiber. The fibers(2) are shown clearly. The diameter of such fibers is 25-100µm. The invention will now be illustrated with typical working examples. Synthesis of Chiral material Example -1 Chiral amine compound (0.5 mole) was taken with 300 ml ethanol in a three necked flask. The flask was kept in an ice bath and fitted with a condenser and a dropping funnel in the side arm. Then 75 ml of 30% NaOH solution was added on it. Benzoyl chloride (0.5 mole) was added dropwise through the dropping funnel during 30-45 min while stirring. The reaction was allowed to continue for 24 h at 0.4°C. Afterwards the reaction mixture was poured in distilled water. The product was precipitated. It was then filtered and washed repeatedly with distilled water. The chiral material was thus obtained as creame colored mass. The yield is -88%. Example - 2 Chiral amine compound (0.5 mole ) was taken with 300 ml isopropanol in a three necked flask which was kept in an ice bath and fitted with a condenser and dropping funnel. Then 75 ml of 30% NaOH solution was added to it. Methacryloyl chloride (0.65 mole) was added and the reaction was carried out as described in Example-1. The yield is - 89%. Example - 3 Chiral amine compound (0.25 mole) was taken with 150 ml isopropanol in a three necked flask along with 0.25 mole triethyl amine. The flask was kept in an ice bath and fitted with a condenser and a dropping funnel. Then freshly distilled acetyl chloride (0.32 mole) was added dropwise through the dropping funnel while stirring. The reaction was allowed to continue in a similar fashion as described in Example- 1. The yield is - 88%. Example - 4 Chiral amine compound (0.25 mole) was taken with 150 ml ethanol in a three necked flask along with 0.25 mole triethyl amine. The flask was kept in an ice bath and fitted with a condenser and a dropping funnel. Then freshly distilled isobutyryl chloride (0.32 mole) was added dropwise through the dropping funnel while stirring. The reaction was allowed to continue in a similar fashion as described in Example-1. The yield is - 88%. Example - 5 Chiral amine compound (0.25 mole) is taken with 150 ml chloroform in a three necked flask along with 0.25 mole triethyl amine. The flask was kept in an ice bath and fitted with a condenser and a dropping funnel. Then freshly distilled tert-butylacetyl chloride (0.32 mole) was added dropwise through the dropping funnel while stirring. The reaction was allowed to continue in a similar fashion as described in Example-1. The yield is - 89%. Preparation of Chiral Fiber Material Example - 6 As synthesized chiral material (l0gm) was taken a 500 ml beaker along with 300 ml of a 50:50 solvent mixture of ethanol and water. The material was dissolved under slightly warm condition. Then it was allowed to crystallize keeping at 4°C for 24 hour without disturbance. Thus a long fiber like colorless crystal of chiral material was obtained. The yield of chiral fiber material is - 82%. Example - 7 As synthesized chiral material (l0gm) was taken a 500 ml beaker along with 200 ml of a 60:40 solvent mixture of isopropanol and water. The material was dissolved under slightly warm condition. Then it was allowed to crystallize keeping at 10°C and kept at that temperature for 36 hour without disturbance. Colorless long fiber of chiral material was thus obtained. The yield of chiral fiber material is- 80%. Example - 8 As synthesized chiral material (l0gm) was taken a 500 ml beaker along with 300 ml of a 50:50 solvent mixture of n-butanol and water. The material was dissolved under slightly warm condition. Then it was allowed to crystallize at room temperature (25°C) in open atmosphere for 36 hour without disturbance. Thus a long fiber like colorless crystal of chiral material was obtained. The yield of chiral fiber material is- 81%. Example - 9 As synthesized chiral material (l0gm) was taken a 500 ml beaker along with 200 ml of a 60:40 solvent mixture of ethanol and chloroform. The material was dissolved under slightly warm condition. Then it was allowed to crystallize keeping at 10°C and kept at that temperature for 36 hour without disturbance. Colorless long fiber of chiral material was thus obtained. The yield of chiral fiber material is- 83%. We Claim:- 1) A process for the preparation of a chiral fiber material for EM wave attenuation, comprising the following steps: a) condensing an acid chloride with a chiral amine compound in 1:1 molar ratio in presence of a solvent and an alkali or a base compound wherein the acid chloride is selected from group consisting of acetyl chloride, acryloyl chloride, tert-butylacetyl chloride, isobutyryl chloride, benzoyl chloride, methacryloyl chloride, 1-nathphoyl chloride, and 2- nathphoyl chloride; and wherein chiral amine compound is selected from a group consisting of D-(+)-a-alkyl aryl amine, L-(-)-α-alkyl aryl amine, L-valine, L-leucine, R-(+)-l-(l-naphthyl)alkyl amine and S-(-)-l-(l-naphthyl)alkyl amine; b) pouring the reaction mixture obtained from step (a) in distilled water followed by filtering to obtain the chiral material as a cream coloured mass; c) drying cream coloured mass obtained in step (b); and d) dissolving the dried mass obtained in step (c) in a solvent mixture and allowing the solution to crystallize at a temperature of 4-30°C for 16 to 48 hours to obtain the chiral fiber material. 2. The process as claimed in claim 1, wherein the alkali is 30 to 60% w/w solution of alkali, wherein the alkali is selected from a group consisting of NaOH and KOH. 3. The process as claimed in claim, wherein the base compound is a diethyl amine. 4. The process as claimed in claim 1, wherein the chiral material in step (c) is dried at 60°C. 5. The process as claimed in claim 1 wherein, the solvent in step (i) is selected from group consisting of ethanol, isopropanol, n-butanol, sec-butanol, chloroform, distilled water and a mixture thereof. 6. The process as claimed in claim 1 wherein, the solvent in said solvent mixture is a mixture of any two solvents selected from a group consisting of alcohol, chloroform and distilled water. 7. The process as claimed in claim 5 wherein, the said solvent mixture is preferably 50:50 alcohol -water mixture. 8. The process as claimed in claim 6, wherein the alcohol is selected from group consisting of ethanol, isopropanol, n-butanol and ethanol. 9. The process for the synthesis of a chiral fiber material as claimed in claim 1 wherein, the length and diameter of said chiral fiber is 1-4 cm and 25-10µm respectively. 10. The process for the synthesis of a chiral fiber material as claimed in claim 1 wherein, the chiral fiber material has a helical conformation of preferably 69%. 11. A chiral fiber material obtained by using the process as claimed in claim 1.

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1260-del-2005-abstract.pdf

1260-DEL-2005-Claims-(15-07-2011).pdf

1260-del-2005-claims.pdf

1260-DEL-2005-Correspondence Others-(15-07-2011).pdf

1260-del-2005-correspondence-others.pdf

1260-del-2005-description (complete).pdf

1260-DEL-2005-Drawings-(15-07-2011).pdf

1260-del-2005-drawings.pdf

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1260-del-2005-form-18.pdf

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1260-del-2005-form-3.pdf

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