Title of Invention

NOVEL SUBSTITUTED PHENYLACETYLENES AND INTERMEDIATES USEFUL FOR THE PREPARATION OF ROOM TEMPERATURE DISCOTIC NEMATIC LIQUID CRYSTALS AND A PROCESS FOR THEIR PREPARATION

Abstract This invention relates to novel branched alkyl chain substituted phenylacetylenes of the general formula (1) Wherein R = branched alkyl chains, the number of carbon atoms in the alkyl chain ranging from 4 to 12. The novel phenylacetylenes of the present invention are useful for the preparation of novel hexaalkynylbenzene derivatives, which are in turn useful for the preparation of discotic namatic liquid crystals. Accordingly these compounds can be used as liquid crystalline material for display devices such as, wristwatches, calculators, cash registers, gasoline pumps, electronic test equipment, laptop computers, TV screens and other large area displays. They can also be used as liquid crystal solvents for spectroscopy.
Full Text

This invention relates to novel substituted phenylacetylenes, more particularly to novel branched alkyl chain substituted phenylacetylenes. The novel phenylacetylenes of the present invention are useful for the preparation of novel hexaalkynylbenzene derivatives, which are in turn useful for the preparation of room temperature discotic namatic liquid crystals. This invention also relates to a series of novel intermediates for the preparation of novel phenylacetylenes. The invention also relates to a process for the preparation of novel branched alkyl chain substituted phenylacetylenes.
The novel branched-chain hexaalkynylbenzene derivatives may find use as discotic nematic (N^) liquid crystals. Accordingly these compounds can be used as liquid crystalline material for display devices such as, wristwatches, calculators, cash registers, gasoline pumps, electronic test equipment, laptop computers, TV screens and other large area displays. They can also be used as liquid crystal solvents for spectroscopy.
Liquid crystal displays (LCDs) have played a vital role in information technology. The current world LCD market runs to billions of dollars and is rapidly growing. The twisted nematic and supertwisted nematic display devices are dominating commercial displays since their invention. The liquid crystal layer in these devices is exclusively the calamitic Quid crystals (composed of rod-shaped molecules). A vast number of calamitic nematic liquid crystals having room temperature mesophases, such as, cyanobiphenyls, phenylpyrimidines, phenylcyclohexanes, Shifts:' bases, etc., have been synthesised and used in practical displays.
The major disadvantage with these type of devices is the narrow and non-uniform viewing cone which is considered to be an unacceptable aspect of their performance. We have recently disclosed a novel approach to overcome this problem by utilizing discotic nematic liquid crystals instead of calamitic nematic liquid crystals. This has been made the subject matter of our Indian Patent Application No. 1131/MAS/98 dated 27.5.98 and the corresponding applications for patent filed in

Europe bearing EPO no. 98 307996.3 dated 1,10.98, in US bearing no. 09/159,743 dated 24.9.98, in Korea bearing no. 98-55028 dated 15,12.98 and in Japan bearing number 334681/98 dated 25.11.98.
Liquid crystals formed by disc-shaped molecules were discovered in 1977 [S. Chandrasekhar, B.K. Sadashiva, and K.A, Suresh, Pramana, 9, 471, (1977)]. Most raesophases formed by these compounds can be classified basically into two classes; the nematic and the columnar. In the colunmar phases molecules are stacked one on top of the other to form columns, the different columns constituting a two dimensional lattice. The potential uses of these columnar phases as quasi-one-dimensional conductors, photoconductors, light emitting diodes, photovoltaic solar cells, etc., have attracted considerable attention [S, Chandrasekhar, in Hand Book of Liquid Crystals, ed. D. Demus, J. Goodby, G.W. Gray, H,-W, Spiess and V. Vill, Wiley-VCH, 1998, Vol. 2B. Chapter VHI; N. Boden and B. Movaghar, ibid. Chapter DC]
The nematic phase formed by disc-shaped molecules is similar to those of the nematic phase of calamitic molecules. A schematic representation of the discotic nematic phase (N^) (of disc-like molecules) is given below. The director n is representing the preferred axis of orientation of the disc-normals (short molecular axes).

Compared to the large number of calamitic molecules showing nematic phase, the number of disk-shaped molecules showing the discotic nematic phase are rare.

Moreover, the N^ phase formed by these materials are high temperature with a narrow thermal range. For any liquid crystal device application, the temperature range of the mesophase and its stability well below and above room temperature are amongst the most important criteria. Hitherto, no room temperature nematic discotic liquid crystal is known. The common procedure for extending the mesophase range of calamitic liquid crystals is by mixing different components and preparing an eutectic mixture but such a procedure has not been applied to discotic neraatics till now. Therefore, it is of great practical interest to prepare room temperature discotic nematic liquid crystals.
The main objective of the present invention is, therefore, to provide novel substituted phenylacetylenes of the general formula (1) and their intermediates of the general formula (2), (3) & (4) where R = branched alkyl chain. The number of carbon atoms in the alkyl chain may range from 4 to 12 , The alkyl chain may preferably be consisting of 1,2 or 3, methyl branch at different positions, for example, 3-methyl octane, 4-methyl octane, 4-methyl nonage, 3, 7-dimethyl octane, 3,7,1 l-triraethyl dodecane, etc.

These intermediates are useful for the preparation of hexalakynylbenzene derivatives of the general formula (5)


where R has the meanings given above.
The compound of the formula (5) and the process for their preparation has been made the subject matter of our copending application no. (A) which is being filed along with this application,
Hexaalkynylbenzenes of the formula (6), where R' = normal alkyl chain a
shown in Table 1, are known to form nematic discotic (N^) phases [B. Kohne, K
Praefcke, Chimia, 41, 196 (1987); M. Ebert, D.A. Jungbauer, R. Kleppinger, J.H.
Wendorff, B. Kohne, K. Praefcke, Liq. Cryst, 4, 53 (1989)]. The thermal behaviour of various reported hexaalkynylbenzenes of the formula (6) is listed below in Table L



Liquid Crystals, ed. D. Demus, J. Goodby, G.W. Gray, H.-W. Spiess and V. Vill, Wiley-VCH, 1998, Vol. 2B, Chapter VII]. No discotic material having stable N^ phase well below and above the ambient temperature is documented.
V
It is evident from the Hterature that when the peripheral alkyl chains are attached to the phenyl ring via an hetero atom such as oxygen or sulphur atom, the melting and clearing temperatures are higher compared to when the alkyl chains are directly attached to the ring, for example, see the above Table 1 entry 3 and 6. When
the heptyl chain is attached to the phenyl ring directly, the melting point is 98*^C and
the clearing point is 13 TC whereas they are 109°C and 193*^C respectively when the
same chain is attached via oxygen atom. It is also well known that when the peripheral aliphatic side chains of various cores are branched, the mesophase is widened but the type of the mesophase formed is not affected by the introduction of branching [P.G. Schouten, J.F. van der Pol, J,W, Zwikker, W, Drenth and SJ. Picken, Mo/. CrysL Liq. Cryst, 1991, 195, 291; D,M. Collard and C.P. Lillya, 7. Anu Chenu Soc, 1991, 113, 8577. P.G. Schouten, J.M, Warman, M.P. deHaas, C. F, van Nostrum, G.H. Gelinck, RJ.M. Nolle, MJ. Copyn, J.W. Zwikker, M.K. Engel, M. Hanack, Y.H. Chang, WX Ford,/ Am, Chenu Soc, 1994,116, 6880],
The main objectives of the present invention is, therefore, to provide novel substituted phenylacetylenes of the formula (1) defined above which are useful for the preparation of hexaalkynylbenzene derivatives of the formula (5) useful as discotic nematic (N^) liquid crystals.
Another objective of the present invention is to provide a process for the preparation of novel substituted phenylacetylenes of the formula (1) defined above and the intermediates which are useful for the preparation of hexalkynylbenzene derivatives of the formula (5) which are in turn useful as discotic nematic (N^) liquid crystals^starting from novel branched alkyl chain substituted phenylacetylenes.

The invention is based on our observation that when the normal alkyl chain in the phenyl ring of hexaalkynylbenzene is replaced with branched alkyl chain and connecting it directly to the phenyl ring, the melting points of the alkynylbenzene derivatives may reduce and consequently stabilise the mesophase.
The preparation of the novel branched alkyl chain substituted phenylacetylenes of the formula (1) defined above according to the present invention is broadly shown in the scheme 1 given below,

TTie compounds of the present invention differ from ^the previous known compounds in the following ways; in the known materials either normal (unbranched) alkyl chain is attached directly to the phenyl ring or branched alkyl chain is connected to the phenyl ring via an oxygen atom whereas in our novel compounds, branched alkyl chain is connected directly to the phenyl ring.

According to the present invention there is provided a process for the . preparation of branched alkyl chain substituted phenylacetylenes of the formula (1) where R has the meanings given above,

which comprises
(i) Acylating bromobenzene of the formula (A) with branched chain acid chlorides by
conventional methods to yield the corresponding ketones of the formula (2).
(ii) Reduction of the ketones of the formula (2) by conventional methods to furnish
the corresponding 4-(branched alkyl)bromobenzenes of the formula (3).
(iii) Reacting the bromobenzenes of the formula (3) with 2-methyl-3-butyn-2-ol to
yield the corresponding protected phenyacetylene of the formula (4).
(iv) Deprotecting the protected phenylacetylene of the formula (4) by conventional
method to yield the corrsponding phenylacetylene of the formula (1).
In a preferred embodiment of the invention the acylation in step (i) may be effected by condensing a branched chain acid chloride with bromobenzene in presence of a Lewis acid such as AICI3 using conventional Friedel-Crafts acylation method. The reduction in step (ii) may be effected by treating the resultant branched chain ketones of the formula (2) with hydrazine hydrate and alkali using conventional Wolff-Kishner reduction. For the reaction in step (iii) the branched alkyl chain substituted bromobenzenes of the formula (3) and 2-methyl-3-butyn-2-ol are used in equiraolecular ratio or more and the condensation may be effected at a temperature
range of SO'^C to 100°C in organic solvents in presence of a coupling catalyst. The solvent such as benzene, ether, tetrahydrofuran, dimethylformamide,

' dimelhylacetamide, N-melhylpyrolidinone, triethylamine, diisopropylamine, etc. or their mixtures are used. The catalyst . employed is selected from tetrakis(triphenylphosphine)palIadium (0), bis(triphenylphosphine)palladium(II) chloride, triphenylphosphine, Cul and an organic base. Preferably the catalyst may be a mixture of bis(triphenylphosphine)palladium(II) chloride, triphenylphosphine and CuL The deprotection in step(iv) may be effected by stirring compound (3) with a base at ambient or elevated temperature in organic solvent for a period upto 4 hrs, preferably for a period in the range of 30 min, to 2 hrs.
According to another embodiment of the invention there is provided a process for the preparation of novel branched alkanoylbromobenzene derivatives of the formula (2) which comprises acylating bromobenzene with branched chain acid chlorides by conventional methods to yield the corresponding ketones of the formula
(2).
According to yet another feature of the invention there is provided a process for the preparation of novel 4-(branched alkyl)bromobenzenes of the formula (3) which comprises reducing the ketones of the formula (2) by conventional methods.
According to still another embodiment of the invention there is provided a process for the preparation of novel 4-(branched alkylphenyl)-2-methylbut-3-yn-2-ol of the formula (4) which comprises reacting the substituted broraobenzenes of the formula (3) with 2-methyl-3-butyn-2-ol to yield the corresponding protected phenylcetylene of the formula (4).
The novel branched alkyl chain substituted phenylacetylenes of the formula (1) where R has the meanings given above react with hexahalobenzene of the formula (7) wherein X represents bromine or iodine in the presence of a coupling catalyst at a
temperature in the range of 25 to 200°C and recovering the compound by
conventional methods to yield novel hexakis(4-(branched
akylphenylethynyl)benzenes of the formula (5) as shown in Scheme 2.


The condensation can be effected by stirring hexabromo- or hexaiodobenzene with six or more equivalent phenylacetylenes. The temperature may be preferably in the
range of 50 to lOO'^C. The condensation may be effected for a period in the range of
four hours to 100 hours, preferably in the range of 12 hours to 24 hours. The condensation may be effected in the presence of organic solvents selected from benzene, tetrahydrofufan, dimethylformamide, N-methylpyrrolidinone, triethylamine, diisopropylamine, etc., or their mixtures, preferably the organic solvent employed may be triethylamine or a mixture of triethylamine and tetrahydrofuran. The catalyst employed may be selected from tetrakis(triphenylphosphine)palladium (0), bis(triphenylphosphine)palladium(n) chloride, triphenylphosphine, Cul and an organic base. Preferable catalyst, may be a mixture of bis(triphenylphosphine)palladium(II) chloride, triphenylphosphine and Cul

The invention is described in detail in the examples given below which arc provided by way of illustration only and therefore should not be construed to limit the scope of the invention.

To a stirred and cooled (O^C) mixture of bromobenzene of the formula (A) (5.5 g, 0.035 raol) and aluminium chloride (1.6 g, 0.012 mol), 4-methylnonanoylchloride (1.9 g, 0.01 mol) was added under argon. The mixture was stirred at O^C for 1 h,
heated at 80°C for 1 h, cooled and poured into 6N HCl. The product was extracted
with dichloromethane (3 X 25 ml), and the combined organic extracts were washed with water and dried with anhydrous sodium sulphate. The solvent was removed in vacuo and the residue was purified by column chromatography (silica gel: hexane-ethyl acetate) to give a colourless liquid of l-BromO'4-(4-methylnonanoyl)benzene of
the formula (8) (2.2 g, 70% based on acid chloride). ^H hfMR data: 5 (CDCI3) 7.83 (2H, d), 7.6 (2H, d), 2.93 (2H, m), 1.82-1.27 (IIH, m), 0.88 (6H, t).


To a stirred and cooled (0*^C) mixture of bromobenzenc (A) (2.75 g, 0.0175 mol),
carbon disulfide (10 ml) and aluminium chloride (1.6 g, 0.012 mol), 4-methylnonanoylchloride (1,9 g, 0.01 mol) was added under argon. The mixture was
stirred atO°C for 1 h, heated at 80°C for 1 h, cooled and poured into 6N HCl. The
product was extracted with dichloromethane (3 X 25 ml), and the combined organic extracts were washed with water and dried with anhydrous sodium sulphate. The solvent was removed in vacuo and the residue was purified by column chromatography (silica gel: hexane-ethyl acetate) to give a colourless liquid of 1-Bromo-4-(4"methylnonanoyl)benzene of the formula (8) (2.5 g, 80%). ^H NMR
dau: 5(CDCI3) 7.83 (2H, d), 7.6 (2H, d), 2.93 (2H, m), 1.82-1.27 (IIH, m), 0.88 (6H, t).


A mixture of the above l-BromO"4-(4'methylnonanoyl)benzene of the formula (8) (1.7 g, 5*5 mmol) obtained by the process described in the Examples 1 and 2 above, hydrazine hydrate (0.8 g, 16 mmol) and potassium hydroxide (1.1 g, 19 mmol) m
diethylene glycol (10 ml) was heated at 130-140 ^C for 2h. The excess of hydrazine
hydrate was distilled off and the temperature was raised to 230-240°C for Ih. The
cooled mixmre was poured into 6N HCl, the product was extracted with ether (3 X 25 ml), and the combined organic extracts were washed with brine and dried with anhydrous sodium sulphate. The solvent was removed in vacuo and the residue was purified by column chromatography (silica gel: hexane-ethyl acetate) to give a colourless liquid of l-Bromo-4-(4-methylnonanyl)benzene of the formula (9) (0.75
g, 46%). ^H NMR: 5 (CDCI3) 7.38 (2H, d), 7.05 (2H, d), 2,53 (2H, t), 1.66-1,1 (13H, m), 0.86 (6H, t).


A solution of l-Bromo-4-(4-methylnonanyl)benzene of the formula (9) (0.72 g, 2 A mmol), obtained by the process described in the Example 3 above, bis(triphenylphosphine)palladium(n) chloride (0.05 g, 0.07 mmol), 2-methyl-3" butyn-2-ol (04 g, 4.8 mmol), triphenylphosphine (0.1 g, 0.76 mmol) and copper(I) iodide (0.05 g, 0.26 mmol) in dry deoxygenated triethylamine (10 ml) was stirred at
60-70^C under argon for 15 h, Triethylamine was removed in vacuo and the residue
was purified by column chromatography (silica gel; hexane-ethyl acetate) to yield 0.36 g, 50% of the product, 4-(4-methylnonanylphenyl)-2-methylbut-3-yn-2-ol of the formula (10).


A solution of l-Bromo-4-(4"methyInonanyl)benzene of the formula (9) (0.72 g, 2.4 mmol), obtained by the process described in the Example 3 above, bis(triphenylphosphine)palladium(n) chloride (0.05 g, 0.07 mmol), 2-methyl-3-butyn-2-ol (0.4 g, 4.8 mmol), triphenylphosphine (0.1 g, 0.76 mmol) and copper(I) iodide (0,05 g, 0.26 mmol) in a mixture of dry THF and dry
deoxygenated tricthylamine (10 ml) was stirred at 60-70°C under argon for 15 h.
Triethylamine was removed in vacuo and the residue was purified by column chromatography (silica gel; hexane-ethyl acetate) to yield 0,50 g, 70% of the product, 4-(4-methybonanylphehyl)-2-methylbut-3-yn-2-ol of the formula (10),


A solution of l-Bromo-4-(4-methylnonanyl)benzene of the formula (9) (0.72 g, 2.4 ramol), obtained by the process described in the Example 3 above, bis(triphenylphosphine)palladium(II) chloride (0.05 g, 0.07 mmol), 2-methyl-3-butyn-2-ol (0.4 g, 4.8 mmol), triphenylphosphine (0.1 g, 0.76 mmol) and copper(I) iodide (0.05 g, 0,26 mmol) in dry deoxygenated diisopropylamine (10
ml) was stirred at 60-70°C under argon for 15 h. Triethylamine was removed in
vacuo and the residue was purified by column chromatography (silica gel; hexane-ethyl acetate) to yield 0.43 g, 60% of the product, 4-(4-methybonanylphenyl)-2-methylbut-3-yn-2-ol of the formula (10).


A solution of l-Bromo-4-(4*methylnonanyl)benzene of the formula (9) (0.72 g, 2.4 mmol), obtained by the process described in the Example 3 above, bis(triphenylphosphine)palladium(n) chloride (0.05 g, 0.07 mmol), 2-methyl-3-butyn-2-ol (0,4 g, 4.8 mmol), triphenylphosphine (0.1 g, 0.76 mmol) and copper(I) iodide (0,05 g, 0,26 mmol) in a mixture of dry THF and dry
deoxygenated diisopropylamine (10 ml) was stirred at 60-70°C under argon for 15
h. Triethylamine was removed in vacuo and the residue was purified by column chromatography (silica gel; hexane-ethyl acetate) to yield 0.46 g, 65% of the product, 4-(4-methylnonanylphenyl)-2-methylbut-3-yn-2-ol of the formula (10).


Powdered potassium hydroxide (180 mg, 3.2 mmol) was added to a solution of 4-(4-methyInonanylphenyl>2-methyl-3-butyn-2-ol of the formula (10) (800 mg, 2,67 mmol) obtained by the process described in the Examples 4 to 7 above, in toluene (10 ml). The mixture was heated to reflux under argon for 1 h. The cooled reaction mixture was poured into ice-water and the solution was neutralised with 0*0 IM hydrochloric acid to pH7, the product was extracted with ether (3 X 25 ml), and the combined organic extracts were washed with brine and dried with anhydrous sodium sulphate. The solvent was removed in vacuo and the residue was purified by column chromatography (silica gel: hexane-ethyl acetate) to give a colourless liquid of 4-(4-
methylnonanylphenyOethyne of the formula (11) (520 mg, 81%). ^H NMR: 5
(CDCI3) 7.41 (2H, d), 7,13 (2H, d), 3,03 (IH, s), 2.58 (2H, t), 1.61-1.1 (13H, m). 0.86 (6H, m).


Sodium hydride (50 mg, 2.1 mmol) was added to a solution of 4-(4-methylnonanylphenyl)-2-methyl-3-butyn-2-ol of the formula (10) (800 mg, 2,67 mmol) obtained by the process described in the Examples 4 to 7 above, in toluene (10 ml). The mixture was heated to reflux under argon for 1 h. The cooled reaction mixture was poured into ice-water and the solution was neutralised with 0.0IM hydrochloric acid to pH7, the product was extracted with ether (3 X 25 ml), and the combined organic extracts were washed with brine and dried with anhydrous sodium sulphate. The solvent was removed in vacuo and the residue was purified by column chromatography (silica gel: hexane-ethyl acetate) to give a colourless liquid of 4^(4-
methylnonanylphenyOacetylene of the formula (II) (515 mg, 80%). *H NMR: 5
(CDCI3) 7,41 (2H, d), 7.13 (2H, d), 3.03 (IH, s), 2.58 (2H, t), 1.61-1.1 (13H, m), 0.86 (6H, m).


A solution of hexabromobenzene of the formula (7) where X = bromo (80 mg,
0.145 mmol), bis(triphenylphosphine)palladiura(n) chloride (75 mg, 0.11 mraol),
4-(4-niethylnonanylphenyl)acetylene of the formula (11) obtained by the process
described in the Examples 8 and 9 above, (420 mg, 1.75 mmol),
triphenylphosphine (150 mg, 0.57 mmol) and copper(I) iodide (75 mg, 0,4 mmol)
in dry deoxygenated triethylamine (10 ml) was stirred at 60-70°C under argon for
24 h. Triethylamine was removed in vacuo and the residue was purified by repeated column chromatography (silica: hexane-ethyl acetate, utmost care should be taken in purifying the product; at least four column chromatographic separations are required to achieve a high purity product. Details of the physical characteristics are given in the last) to yield 55 mg, 25% of the hexakis(4-4-methylnonanylphenylethynyl)benzene of the formula (12).


Hexaiodobenzene (83 mg, 0*1 mmol) of the formula (7) where X = iodo, bis(triphenylphosphine)palladium(II) chloride (50 rag, 0.07 mmol), 4-(4-methylnonanylphenyl)acelylene (11) obtained by the process described in the Examples 8 and 9, (242 mg, 1.0 mmol), triphenylphosphine (100 mg, 0,38 mmol) and copper(I) iodide (50 mg, 0.26 mmol) were added into dry deoxygenated
triethylamine (10 ml) and the reaction mixture was stirred at lOO^C under argon for
4 h. Triethylamine was removed in vacuo and the residue was purified by column chromatography (silica gel, hexane-ethyl acetate) to yield 15 mg, 10% of the hexakis(4-4-methylnonanylphenylethynyl)benzene of the formula (12).


Hexaiodobenzene (83 mg, 0,1 mmol) of the formula (7) where X = iodo, bis(triphenylphosphine)palladium(II) chloride (50 mg, 0,07 mmol), 4-(4-methylnonanylphenyl)acetylene (U) obtained by the process described in the Examples 8 and 9 (242 mg, 1,0 mmol), triphenylphosphine (100 mg, 0.38 mmol) and copper(I) iodide (50 mg, 0.26 mmol) were added into dry deoxygenated
triethylamine (10 ml) and the reaction mixture was stirred at 100°C under argon for
24 h. Triethylamine was removed in vacuo and the residue was purified by column chromatography (silica gel, hexane-ethyl acetate) to yield 53 mg, 35% of the hexakis(4-4-methylnonanylphenylethynyl)benzene of the formula (12),
SI


Hexabromobenzene of the formula (7) where X = bromo, (55 mg, 0.1 mmol) bis(triphenylphosphine)palIadium(n) chloride (50 mg, 0.07 mmol), 4-(4-methylnonanylphenyl)acetylene (11) obtained by the process described in the Examples 8 and 9, (242 mg, 1.0 mmol), triphenylphosphine (100 mg, 0,38 mmol) and copper(I) iodide (50 mg, 0.26 mmol) were added into a mixture of dry and deoxygenated THF (10 ml) and triethylamine (5 ml). The reaction mixture was
heated at 70-80°C under argon for 24 h. Solvents were removed in vacuo and the
residue was purified by column chromatography (silica gel, hexane-ethyl acetate) to yield 18 mg, 12% of the hexakis(4-4-methylnonanylphenylethynyl)benzene of the formula (12),.


Hexabromobenzene of the formula (7) where X = bromo, (55 mg, 0.1 mmol), bis(triphenylphosphine)palladium(II) chloride (50 mg, 0.07 mmol), 4-(4-raethylnonanylphenyl)acetylene (11) obtained by the process described in the Examples 8 and 9, (242 mg, 1.0 mmol), triphenylphosphine (100 mg, 0.38 mmol) and copper(I) iodide (50 mg, 0.26 mmol) were added into dry and deoxygenated
diisopropylamine (10 ml). The reaction mixture was heated at 90-100°C under
argon for 24 h. Solvents were removed in vacuo and the residue was purified by column chromatography (silica gel, hexane-ethyl acetate) to yield 30 mg, 20% of the hexakis(4-4-methylnonanylphenylethynyl)benzene of the formula (12).
Physical characteristics o f the compound hexakis(4-4-methylnonanylphenylethynyObenzene.
The product hexakis(4-4-methyhionanylphenylethynyl)benzene of the formula (12) isolated in experiment no. 10-14 by column chromatography was found to be

homogenous on TLC and the HPLC purity (silica; hexane; flow 1,2, R,T. 39.25 min) was more than 99%. MS data: m/z 1520.2;.*H NMR data: 5 (CDCI3) 7.58
(12H, d), 7.20 (12H, d), 2,64 (12H, t), 1,63-1.1 (78H. m), 0.90 (36H, m), *'C NMR data: 5 (CDCI3) 144,03, 131.79, 128.52, 127,3, 120.53, 99.41, 87.06,
36.95, 36,72, 36.36, 32.66, 32.21, 28.78, 26.72, 22.70. 19.65 and 14.10, Thermal behaviour: The thermal behaviour of the compound hexakis(4-4-mcthylnonanylphenylethynyl)benzene isolated from different batches was checked by polarising microscopy and by differential scanning calorimetry. In all the cases, material shows a room temperature nematic (N^) phase. However, the melting and isotropic temperatures are different. This could be due to the stereohetrogeneity of the product (with one chiral center in each of the six side chains the product derived from racemic starting materials consist of a mixture of various stereoisomers). Variation of stereoisomers in the mixture could be the cause of varying melting and
clearing points in different batches. The melting point was observed in between 0°C
to 10°C and the clearing point in between 40°C to 80°C on heating. Upon cooling
the isotropic liquid, the discotic nematic phase appeared with a very limited supercooling and the material crystallises in between 0°C to - 2 PC.
Advantages of the invention.
The novel substituted phenylaceetylenes of the formula (1) of the present invention are important starting materials for the preparation of novel hexaalkynylbenzene derivatives. The nematic phase shown by these hexaalkynylbenzene derivatives is stable well below and above the ambient temperature and, therefore, very suitable for liquid crystal display (LCD) devices. The liquid crystal display (LCD) device having discotic nematic liquid crystals instead of calamitic nematic liquid crystals has advantages over the conventional LCD devices in that it has a wide and symmetrical viewing angle and no reversal of the contrast ratio in any direction.





We Claim
1 Novel branched alkyl chain substituted phenylacetylenes of the general formula (1)

wherein R = branched alkyl chains, the number of carbon atoms in the alkyl chain ranging from 4 to 12.
2. Novel phenylacetylene derivatives of the general formula (1) as claimed in claim 1 wherein the substations in the branched chain is selected from alkyl, halogen, hydroxy, carboxyl, nitro, cyan, aryl, thioalkyl, alkoxy and acyloxy groups.
3. Novel phenylacetylene derivatives of the general formula (1) as claimed in claims 1 and 2 wherein the alkyl chain is of 1,2 or 3 methyl branched at different positions.
4. Novel branched alkanoyl bromobenzene derivatives of the formula (2)

wherein R = branched alkyl chains, the number of carbon atoms in the alkyl chain ranging from 4 to 12,
5. Novel branched alkanoyl bromobenzene derivatives of the formula (2) as claimed
in claim 4 wherein the substituents in the branched chain is selected from alkyl,
halogen, hydroxy, carboxyl, nitro, cyano, aryl, thioalkyl, alkoxy and acyloxy groups.

6. Novel branched alkanoyl bromobcnzcne derivatives of the formula (2) as claimed
in claims 4 and 5 wherein the alkyl chain is of 1, 2 or 3 methyl branched at different
positions.
7. Novel branched alkyl chain substituted bromobenzene derivatives of the formula
(3)
wherein R = branched alkyl chains, the number of carbon atoms in the alkyl chain ranging from 4 to 12,
8. Novel branched alkyl chain substituted bromobenzene derivatives of the fondle (3) as claimed in claim 7 wherein the substituents in the branched chain is selected from alkyl. halogen, hydroxy, carboxy, nitro, cyano, aryl, thioalkyl, alkoxy and acyloxy groups.
9. Novel branched alkyl chain substituted bromobenzene derivatives of the formula (3) as claimed in claims 7 and 8 wherein the alkyl chain is of 1, 2 or 3 methyl branched at different positions.
10. Novel branched alkylphenyl-2-methylbut-3-yn-2-ol derivatives of the fondle (4)

wherein R = branched alkyl chains, the number of carbon atoms in the alkyl chain ranging from 4 to 12,

11. Novel branched alkylphenyl-2-methylbut-3-yn-2-ol derivatives of the formula (4) as claimed in claim 10 wherein the substituents in the branched chain is selected from alkyl, halogen, hydroxy, carboxy, nitro, cyano, aryl, thioalkyl, alkoxy and acyloxy groups.
12. Novel branched alkylphenyl-2-methylbut-3-yn-2-ol derivatives of the formula (4) as claimed in claims 10 and 11 wherein the alkyl chain is of 1, 2 or 3 methyl branched at different positions.
13. A process for the preparation of novel branched alkyl chain substituted
phenylacetylenes of the general formula (1) where R has the meanings given above.

which comprises
(i) Vacillating bromobenzenc of the formula (A) by conventional methods to yield the
corresponding ketones of the formula (2).
(ii) Reduction of the ketones of the formula (2) by conventional methods to furnish
the corresponding 4-(branched alkyl)bromobenzenes of the formula (3).
(iii) Reacting the bromobenzenes of the formula (3) with 2-methyl-3-butyn-2-ol in
the presence of a coupling catalyst to yield the corresponding protected
phenylacetylene of the formula (4).
(iv) Deprotecting the protected phenylacetylene of the formula (4) by conventional
method to yield the corresponding phenylacetylene of the formula (1).

14. A process as claimed in claim 13 wherein the acylation in step (i) is effected by condensing a branched chain acid chloride with bromobenzene in presence of a Lewis acid such as AICI3 using conventional Frieda-Crafts acylation method.
15. A process as/claims 13 & 14 wherein the reduction in step (ii) is effected by treating the above branched chain ketones with hydrazine hydrate and alkali using conventional Wolff-Kosher reduction method,

16. A process as claimed in claims 13 to 15 wherein the branched alkyl chain substituted bromobenzene and 2-methyl-3'butyn-2-ol in step (iii) are used in equimolecular ratio or more.
17. A process as claimed in claim 16 wherein the condensation of the two
components is carried out at a temperature range of 50*^0 to 100°C in the presence of
organic solvents.
18. A process as claimed in claim513 to 17 wherein the solvent such as benzene, ether, tetrahydrofuran, dimethylformamide, dimethylacetamide, N-methylpyrolidinone, triethylamine, diisopropylamine, etc. or their mixtures is used.
19. A process as claimed in claims 16 to 18 wherein the catalyst employed is selected front tetra is(triphenylphosphine)palladium(0), bis(triphenylphosphine)palladium(II) chloride, triphenylphosphine, Cul, etc.
20. A process as claimed in claim 19 wherein the catalyst used is a mixture of bis(triphenylphosphine)palladium(II) chloride, triphenylphosphine, Cul, and an organic base.
21. A process as claimed in claims 13 to 20 wherein the condensation is effected for a period upto 100 hrs, preferably for a period in the range of 12 to 24 hrs.
22. A process as claimed in claims 13 to 21 wherein the deprotection in steep(iv) is effecetd by stirring compound (3) with a base at ambient or elevated temperature in the presence of an organic solvent.
23. A process as claimed in claim 22 wherein the solvent such as benzene, ether, tetrahydrofuran, tolune, methanol, ethanol, etc., or their mixtures is used.

24. A process as claimed in claims 22 and 23 wherein the base such as sodium
hydroxide, potassium hydroxide, sodium hydride, etc., is used.
25. A process as claimed in claims 22 to 24 wherein the deprotection is effected for a period unto 4 hrs, preferably for a period in the range of 30 min. to 2 hrs*
26. A process for the preparation of novel substituted phenylacetylenes of the general formula (1) where R has the meanings given above substantially as herein described with reference to Examples 8 and 9,
27. A process for the preparation of 4-(branched alkanoyl)bromobenzene of the
formula (2) which comprises vacillating bromobenzene of the formula (A) by
conventional methods to yield the corresponding ketones of the formula (2).
28. A process as claimed in claim 27 wherein the acylation is effected by condensing a branched chain acid chloride of the formula Rocco where R has the meanings given above with bromobenzene of the formula (A) in presence of a Lewis acid such as AICI3 using conventional Frieda-Crafts acylation method.
29. A process for the preparation of the compounds of the formula (2) substantially as herein descried with reference to the examples 1 and 2,
30. A process for the preparation of 4-(branched alkyl)bromobenzenes of the
formula (3) which comprises reducing the ketones of the formula (2) by conventional
methods.
31. A process as claimed in claim 30 wherein the reduction is effected by treating the above branched chain ketones of the formula (2) with hydrazine hydrate and alkali using conventional Wolff-Kishner reduction method.
32. A process for the preparation of the compounds of the formula (3) substantially as herein descried with reference to the example 3.
33. A process for the preparation of 4-(branched alkylphenyl)-2-methylbut-3-yn-2-ol of the formula (4) which comprises reacting the bromobenzenes of the formula (3) with 2-methyl-3-butyn-2-ol to yield the corresponding protected phenylacetylene of the formula (4)

34. A process as claimed in claim 33 wherein the reaction is effected by coupling a branched alkyl chain substituted bromobenzene of the formula (3) with 2-methyl-3-butyn-2-oI in presence of a coupling catalyst in organic solvent at room temperature or elevated temperature,
35* A process for the preparation of compounds of the formula (4) substantially as herein described with reference to the Examples 4 to 1.


10. A process as claimed in claims 4 to 9 wherein the condensation is effected for a
period upto 100 hrs, preferably for a period in the range of 12 to 24 hrs.
11. Novel hexaalkynylbenzene derivatives of the general formula (1) defined in claim 1 substantially as herein described with reference to the Examples 10 to 14.
12. A process for the preparation of novel hexaalkynylbenzene derivatives of the general formula (1) defined in claim 1 substantially as herein described with reference to the Examples 10 to 14.


Documents:

927-mas-1999-abstract.pdf

927-mas-1999-claims filed.pdf

927-mas-1999-claims granted.pdf

927-mas-1999-correspondnece-others.pdf

927-mas-1999-correspondnece-po.pdf

927-mas-1999-description(complete)filed.pdf

927-mas-1999-description(complete)granted.pdf

927-mas-1999-form 1.pdf

927-mas-1999-form 19.pdf

abs-927-mas-1999.jpg


Patent Number 214013
Indian Patent Application Number 927/MAS/1999
PG Journal Number 13/2008
Publication Date 31-Mar-2008
Grant Date 23-Jan-2008
Date of Filing 20-Sep-1999
Name of Patentee CENTRE FOR LIQUID CRYSTAL RESEARCH
Applicant Address P.O BOX NO. 1329, JALAHALLI, BANGALORE - 560 013,
Inventors:
# Inventor's Name Inventor's Address
1 SANDEEP KUMAR CENTRE FOR LIQUID CRYSTEL RESEARCH, P.O BOX NO. 1329, JALAHALLI, BANGALORE - 560 013,
2 SANJAY KUMAR VARSHNEY CENTRE FOR LIQUID CRYSTEL RESEARCH, P.O BOX NO. 1329, JALAHALLI, BANGALORE - 560 013,
3 SIVARAMAKRISHNA CHANDRASEKHAR CENTRE FOR LIQUID CRYSTEL RESEARCH, P.O BOX NO. 1329, JALAHALLI, BANGALORE - 560 013,
PCT International Classification Number C07C 39/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA