Document ZB5nEpOQ3nQ19ekwRaBmaYX07

E. I. DU PONT DE NEMOURS & COMPANY 256 VANDERPOOL STREET NEWARK, MEW JERSEY Uo. 71-7 Copy Mo, 17 r et ur n t o JACKSON LABORATORY FILE ROOM NEWARK PLANT PIGMENT COLOR RESEARCH REPORT Derivatives of Squaric Acid Period Covered (part Time) October 1969 - January 1971 FILE: 223 DATE, 3/12/71 N42409 KN-71-7 Copy NO. 17 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Numerical File Research Office File 223 Newark Library File 223 M.Hunt/E.Gonick, Pigments, Wilmington W.S.Struve/J.Jackson/A.R.Hanke R.H.Wetzel, Newport (Circ. and File) e .F.Klenke/B.H.Perkins/Library P.j.Monahan, Newark (Vital Records) N.G.Fisher, central Research Dept., Wilmington Newark Library for central Report Index Newark Library - for Central Report Index Lawrence R. Lemer E;E:Jaffe Extra Extra Extra Extra Extra NEWARK PLANT PIGMENT COLOR RESEARCH REPORT SUBJECT: Derivatives of Squaric Acid PERIOD COVERED: (Part Time) October 1969 - January 1971 SUBMITTED BY: Lawrence j r . Lemer Date Submitted: 1/18/71 APPROVED BY: Date Released: 3/12/71 ABSTRACT Squaric Acid has been substituted in the 1,3<-positions with a variety of nucleophilic reagents. Many of the products are characterized by extremely high extinction coefficients (mostly blues) and generally poor lightfastness. Others in the yellow to orange range show less strength but promising lightfastness. r et ur n t o JACKSON LABORATORY FILE ROOM DUP050082608 -1 I. ,,XhtrodUction Sguaric Acid (3,4-dihydroJcycyclobutenedione), 1, a colorless, strongly acidic material (pic- =2,pfc ^1), was first"prepared in 19591. It has been suggested2 that the dianion has considerable aromatic character., and this aromaticity provides the driving force for ionization. Squaric Acid was originally prepared1'3 from chlorotrifluoroethylene (2) as fellows? P cl Fp 2 Zxx s, Pa Fa | j F Fa 1 ii Fa More recently a German firm has reported4 a commercial synthesis starting with hexachlorobutadiene (). The reaction is carried out in one step (route B) without isolation of the intermediates. DUP050082609 Squaric Acid undergoes many reactions, but this report will be limited, in general, to products formed by reaction with nucleophilic reagents to produce 1,3-substituted "squarates", 4,(eyelobutenedione diolates or cyclobutenediylium diolates) with pigmentary potential. 4 45 The interested reader can consult recent review articles ' ,or additional information, II Summary and Conclusions 1, 48 different derivatives of Squaric Acid have been prepared and evaluated in the Fadeometer.2 2. Only two made, thus far, warranted further testing and are out on Florida exposure in TAE-3 DUP050082610 -3 a. The orange product derived from barbituric acid. b. The orange product derived from 2-amino fluorenone. h i . Patent Status As none of these compounds is of commercial interest at this time, no work has been done toward establishing novelty and utility for a patent application, IV, Discussion Substituted Benzene Derivatives These compounds are, generally, blues of extreme strength (some having molar extinction coefficients of greater than 200,000 in solution), They also show some solubility in polar solvents and relatively poor lightfastness. They are easily prepared by reacting stoichiometric amounts of the activated aromatic compound with squaric acid in acetic acid or amixture of 1-butanol and benzene (azeotropic removal of water). None of these compounds seemed to be of further interest due to the color (blue) and relatively poor lightfastness. Table I summarizes the results found with each compound. DUP050082611 -4 TABLE I SUBSTITUTED BENZENE DERIVATIVE OF SQUARIC ACID 0 AROMATIC COMPOUND CH3 c 6K EXP.NO, 1921/27 COLOR Blue FADEOMETER Tint sfade 24 hrs. Maas: dark ens COMMENTS Purchased from Aldrich Chemical Co. 1937/7 Blue Tint s fade 72 hrs. Mass j dark ens OH group may improve lightfastness 1921/56 1921/60 Violet Tint sfade EtOH 100 hrs. /max..573 Mass:dark- (200,000)ens Violet DMSO /max. 583 Soluble but relatively good lightfastness poor yield in prep. Very poor yield, not fully characterized? appears to fluoresce 1921/48 Blue Tint s fade CHCl3 200 hrs. /max,586 Mass sdark- (153,000)ens Soluble but relatively good 1ight fastness Blue Tint:fade DMSO 200 hrs. -i Max. 586 Mass: dark- (132,000)ens Relatively soluble; relatively lightfast 1937/46 Blue Tint s fade 24 hrs. Masssslight change Conjugation does not aid 1ight fastnes s DUP050082612 AROMATIC COMPOUND EXP. NO 1921/51 -5TABLE I CONTINUED COLOR FADEOMETER COMMENTS No reaction?not sufficiently nucleo philic 1921/52 1921/53 1921/61 1921/71 1921/79 Products From Activated Methylene Compounds These compounds are hypsochromically shifted relative to the benzene derivatives (less conjugation). They also show decreased strength, but in some cases, lower solubility and enhanced lightfastness . The procedures for preparing these compounds are the same as those previously discussed. One compound of particular interest is the insoluble orange product formed from barbituric acid (>) which has been mentioned briefly in the literature*. In ZnO extension, it shows 0" DUP050082613 -6 - a slight change initially (24 hrs.) but. after 300 hrs, still retains most of its color. It looks fair after 508 hrs,/ hut the masstone shows only a slight change. Though it does not have the strength of the benzene substituted compounds/ it is still quite strong DMF (A max 492)60/000). A sample is out on Florida exposure in thermosetting acrylic enamel (t a e -3). Table II summarizes the results found with these compounds. TABLE II PRODUCTS FROM ACTIVATED METHYLENE COMPOUNDS AND SQUARIC ACID 1921/32 1921/69 1937/57 Orange DMF Amax 492 (60/000 Orange DMSO Amax 499 (94/000) Orange 1937/47 Orange 1937/14 Purple Tint and Turns brown upon masstone: dispersion milling. good 300 hrs . See discussion section for further information T int and masstone: severe fade 24 hrs. Soluble and very poor lightfastness. Both due to lack of intermolecular H-bonding? Tint and masstone: slow fade 24 hrs. and up Fair elemental analysis intermediate solubi1ity/inter- mediate lightfastness. Tint and masstone: fade in 24 hrs,, Ehirly soluble poor lightfastness Tint-fades 24 hrs. Soluble DUP050082614 -7- TABLE XI CONTINUED X EXP. NO. COLOR FADEOMBTER COMMENTS 1937/8 1937/37 Dull Orange Tint and Mass: Fade 24 hrs. Soluble in reaction medium; orange solution 1937/35 Violet Tint and Mass; severe fade 24 hrs. Brown Colorless p-nitroAAA 1921/50 yellow Ochre Tintsfade 24 hrs * Mass s darkens Pale Yellow Soluble in reaction medium; dark red solution Poor yield; not further character ised Get off 2x theoretical amtt of water. Very insoluble, structure unknown Unknown structure Poor yield unknown structure DUP050082615 -8 TABLE tt (COH'T) X______________F.XP HO. COLOR FAPEOMBTSR COMMENTS 0NHCOCHCONH0 1937/61 I Pale gold Mass and Gives good elements' tint: analysis for 2:1 fade 24 hrs . adduct No reaction in AcOH or butanol/ benzene No reaction under a variety of conditions No reaction Products soluble in reaction medium; at least 4 major products (TLC) Substituted Aniline Derivatives The third class of compounds prepared can be considered derivatives of aniline* where the amino group behaves as the nucleophile upon reaction with squarie acid5'6,7 These compounds range in color from pale yellow to orange. (with notable exceptions) are relatively soluble and show poor lightfastness There was one unusual 1 si adduct found in this series which will be discussed first. Most It has been reported5 that 3- aminopyridine forms a 1:1 adduct (6) instead of the usual 2:1 product. DUP050082616 -9- 6 This compound was found to he insoluble (1921/43) and high melting (> 320c) , but has most of its absorption in the UVi DMP (2 max 400 (14,000). A few quinoline derivatives were prepared, but either were not strong enough or showed poor lightfastness. Table III summarises these results. X -NHa' - NO. 1937/2 niche1 chelate of above 1937/15 NHCOCHa 1937/9 rphOF Red-yellow FADKOMETER COMMENTS Tint s fade DMF insoluble 72 hrs. tint and mass: Masssdarkens show some color 96 hrs. after 168 hrs. Green-yellow Tint:fades 24 hrs. Mass:darkens 24 hrs. Pale yellow Mass:fades 90 hrs. Relatively poor elemental analysis OH 1937/12 Pale green- yellow Pot "rubbed" out The*results found with the "normal" 2:1 anilihe derivatives, with the exception of the "keto" compounds are shown n table IV. DUP050082617 - .10 TABLE IV ARYLAMINO SUBSTITUTED SQUARIC ACl R X_______ EXP, NO. 1921/34 1921/37 1921/38 NH 1921/39 1937/52 FADEOMETER .mm.RESETS.-. O range d mf Anvar 497 (64,000) .COMMENTS Very soluble and high melting (368-370t decomp:) Pale green" yellow Tint:fades 24 hrs. Mass t darkens Fairly soluble Green-yellow Tintsfades 24 hrs. Mass i darkens P ed~ye1low Tintifades 24 hrs. Mass: darkens polymeric m.p.> 470 (darkens 350) polymeric m.p. > 470 (darkens 270*) Green-yellow Tintsfades 24 hrs. Mass t slight change Green-ye1low t int:fades 24 hrs. Mass * darkens Yellow DMF soluble m.p.210-220 (decomp) Blue-gray $ints fade 24 hrs. Mass? no apparent change Polymeric m.p.> 450 DUP050082618 - 11 - TABLE IV CONTINUED y EXP NO COLOR FADEOMETER " RESULTS COMMENTS 1937/6 Dull violet Tint:fade Polymeric 24 bra. m.p. 450 Mass: slight fade 1949/15 Brown Not further investigated 1949/8 -- - No reaction 1949/16 Dull yellow Tint:fades 24 hrs. Mass: fades 24 hrs. Poor analysis A series of acetophenone/benzophenone and fluorenone derivatives were prepared and showed interesting physical properties, summarized on Table V. TABLE V KETO ARYLAMINO DERIVATIVES OF SOUARIC ACID I.R. Carbonyl 10-best NB Frequency 1-color gone No 1= lowest Color 24 hrs. Comments 1937/78 Orange 10 Very in soluble fairly good lightfast ness 407 hrs. Orange IMF max. 483 (38,000) Yellow 7 2 Still some color after 407 hrs. in Fadeometer Recrystallized from DMF DUP050082619 1949/6 - 12 - TABLE V CONTINUED 1 Red-yellow S Greenyellow 1 1949/10 1 / 1949/9 2 1949/19 3 Redyellow solid DMF /max. 450(40,000) 4 Green-yellow solid DMF hmax. 442(35,000) 3 Greenyellow 1 Recrystal lized from DMF. Some color after 147 hrs. in Fadsometer Hot recrystal*lized lout. showed good elemental analysis Fairly soluble DMF recrystal lized Soluble DMF recrystal lized Soluble DMF recrystal lized It should he noted that within each group (excluding, for the moment, 2-aminofluorenone), the compound with the lowest frequency I.R. carbonyl band (lowest energy) is the one having the carbonyl adjacent to the nitrogen. These correspond, as well, to the more photo stable compounds. This behavior is analogous to that found in classical solution photochemistry. in solution, it has been shown that reversible hydrogen transfer helps prevent photoreduction (intramolecular H-bonding; also leads to lowering of carbonyl frequency) and a similar mechanism might be postulated here. The para-substituted materials can be stabilized via electron donation from nitrogen to the carbonyl, with which it is conjugated. This explanation also has precedent in classical solution photochemistry. The meta--substituted compounds cannot he stabilized in either way and in all but one case show the poorest photostability. The compound which appears to be anomalous is the product from 2-aminofluorenone (call 2AF). A clue to its enhanced photostability may lie in its bathochromically shifted color vs. the other metasubstituted fluorenone (4-aminofluorenone) derivative? orange, as DUP050082620 - 13 opposed to yellow. Though in 2AF direct conjugation between the nitrogen and the carbonyl is absent, conjugation can occur via the other fused benzene ring as showni This extended conjugation might account for the orange color and possibly a less energetic (less reactive?) excited state. The acetoand benzophenones cannot have this type of conjugation, and thus, photostabilization. Another mode of stabilization, instead of, or in addition to, the first is intermolecular hydrogenbonding. Compound 2AF may be able to pack in the crystal lattice in such a way as to maximize intermolecular H-bonding and thus maximize photostability via reversible intermolecular hydrogen transfer. A large sample of 2AF is out on Florida exposure in thermosetting acrylic enamel (TAB-3), V, Experimental Experimental details can Ire found in the references included in the tables. DUP050082621 14 - REFERENCES 1. s. Cohen. J.R.Lacher, and J.D.Park, j.Amer.Chem.SOc. .81/3480(1959). 2. S.W.Tobey, and R.West, Tetrahedron Letters, 1179(1963). 3. J.D. Park and 8.Cohen, 3M, 0.9. 3,059,030. 4. chetnlsche Werlke Huls Ag.See: G. Machs and P. Hegenberg Angew.Chem. (Xnt.Ed.), , 888(1966). 5. H.-E. Sorenger and W. Ziegenbein, Angew.Chem.(Int.Ed.), 7, 530 (1968). ~~ 6. G. ManecVe and J. Gauger,-Tetrahedron Letters, 3507(1967); 1339 (1968). 7. J. Gauger and G. Maneefce, Chew.Ear..103, 2696(1970). 8. For example sees ft. Turro, "Molecular Photochemistry", w.A.Benjamin Inc., New York, 1967, pp 137-154. U. DU P050082622