United States Patent (19) 11 3,971,808 Baumann et al. (45) July 27, 1976

54). SPIRODHPYRANS AND CHROMOGENIC 56) References Cited MATERIALS FOR COPYING PROCESSES UNITED STATES PATENTS

75) Inventors: Hans Baumann; Andreas 2,978,462 4/1961 Berman et al...... 260/345.2 Oberlinner, both of Ludwigshafen, 3,022,318 2/1962 Berman et al...... 260/345.2 Germany 3,666.525 5/1972 Kimura et al...... 260/345.2 73) Assignee: BASF Aktiengesellschaft, Ludwigshafen (Rhine), Germany Primary Examiner-James O. Thomas, Jr. Assistant Examiner-Nicky Chan 22 Filed: May 7, 1974 Attorney, Agent, or Firm-Johnston, Keil, Thompson 21 Appl. No.: 467,829 & Shurtleff 30 Foreign Application Priority Data 57 ABSTRACT May 11, 1973 Germany...... 2323803 Spirodipyrans based on condensed pyrylium salts and 4-dialkylamino-2-hydroxybenzaldehydes, their manu 52) U.S. Cl...... 260/345.2; 8/7; facture and their use as chromogenic materials in 260/.571; 260/576 pressure-sensitive recording materials, particularly 511 Int. Cl”...... C07D 311/02 copying papers. 58 Field of Search...... 260/345.2 6 Claims, No Drawings 3,971,808 2 SPRODIPYRANS AND CHROMOGENIC R is phenyl or phenyl substituted by chlorine, bro MATER ALS FOR COPYING PROCESSES mine, nitro or C- alkyl, This invention relates to spirodipyrans of formula I R’ is hydrogen, C-8 alkyl or phenyl and 5 Rand R are C- alkyl or cyanoalkyl of from 2 to 6 carbon atoms. The spirodipyrans of formula I are compounds hav ing little or no color. When dissolved in non-polar or weakly polar solvents such as hydrocarbons, chlorohy O drocarbons and esters, they give intense blue color ations when acid substances are added. This reaction, I which is also caused by kaolin, zeolites, bentonite, silicic acid and phenolic condensation products, makes the compounds suitable for use as dye precursors in 15 pressure-sensitive recording materials, particularly copying papers. Preferred values of Rare, in addition to hydrogen, methyl, ethyl and phenyl. Of particular industrial signif icance are the compounds of the formulae: 20 in which A denotes a benzene or naphthalene nucleus option ally monosubstituted or polysubstituted by chlo rine, bromine, alkoxy or carboxylic ester,

R" denotes a benzene nucleus optionally mono- or 25 poly-substituted by chlorine, bromine, alkyl or nitro, R* denotes hydrogen or alkyl or aryl both of from 1 to 8 carbons and 30 R and R denote a C- alkyl radical optionally sub stituted by cyano. More particularly, it relates to spirodipyrans of for mula a 35

40 Ta.

s 45 in which A is s 50

wherein the substituent R denotes hydrogen or a 55 -COOCH or -COOCHs group. Bl Suitable values of RandR, which are preferably the B2 same, are methyl, ethyl, propyl and (3-cyanoethyl. The spirodipyrans of formula I may be prepared by B K / or 5 condensation of 2-alkyl-3-arylbenzopyrylium salts or B ena 60 2-alkyl-3-arylnaphthopyrylium salts (compounds of E2 formula II) or the corresponding g-(2-hydroxyaryl 1) vinyl ketones (compounds of formula III) with 4 dialkylamino-2-hydroxybenzaldehydes (compounds of formula IV) or from 6-(2-hydroxy-4-dialkylaminoaryl wherein B, B' and Beach individually denotes hy- 65 1) vinyl ketones (compounds of formula VI) and o drogen, chlorine, bromine, methoxy, ethoxy or hydroxyaldehydes (compounds of formula V) accord carboalkoxy containing C- alkoxy, ing to the following schemes in conventional manner: 3,971,808 3

R + OCH N -up O1 2 Ys" o? sh-Cy-K -- xe R 2 OH 69 R" II IV.

Rl R If H=(--CH-Rf R H=C-C-C-C GCA O -- OCH N n", --> OH . HO Ol n-R r OH Ho III IV

2 CHO RH RCH-C-C- R OH HO 1 OC. “soleN' V WI

Specific examples of suitable starting materials are as Compounds of formula V follows: salicylaldehyde Pyrylium salts of formula II in the form of their chlo 2-hydroxy-5-bromobenzaldehyde rides, perchlorates, tetrafluoroborates, tetrachlorofer 2-hydroxy-5-chlorobenzaldehyde rates or trichlorozincates 2-methyl-3-phenylbenzopyrylium salt 6-oxynaphthaldehyde 2-methyl-3-phenylnaphtho-2, 1-b-pyrylium salt 2-hydroxy-3-carbomethoxy-1-naphthaldehyde 2-methyl-3-phenyl-10-carbomethoxynaphtho-2, 1 50 2-hydroxy-3-carboethoxy-1-naphthaldehyde. b-pyrylium salt Compounds of formula VI 2-benzyl-3-phenylbenzopyrylium salt 2-benzyl-3-phenylnaphtho-E2, 1-b-pyrylium salt benzyl-(2-hydroxy-4-dimethylamino-styryl) ketone 2-methyl-3-phenyl-6-bromo-benzopyrylium salt benzyl-(2-hydroxy-4-diethylamino-styryl) ketone 55 benzyl-(2-hydroxy-4-(N-methyl-N-6-cyanoethyl)- 2-ethyl-3-phenylbenzopyrylium salt. styryl)ketone Aldehydes of formula IV benzyl-(2-hydroxy-4-dimethylamino-o-methyl-sty ryl) ketone 4-dimethylamino-2-hydroxybenzaldehyde benzyl-(2-hydroxy-4-diethylamino-o-methyl-styryl) 4-diethylamino-2-hydroxybenzaldehyde ketone 4-(N-methyl-N-g-cyanoethylamino)-2-hydroxyben 60 benzyl-(2-hydroxy-4-diethylamino-a-phenyl-styryl zaldehyde. ; ketone. g-(2-Hydroxyaryl-1)-vinyl ketones of formula III The condensation is conveniently carried out in or methyl-(2-hydroxy-a-phenylstyryl) ketone ganic solvents which are liquid at the temperature of ethyl-(2-hydroxy-a-phenylstyryl) ketone 65 the reaction, for example alcohols, carboxylic acids, benzyl-(2-hydroxy-a-phenylstyryl) ketone carboxylic anhydrides, carboxamides, hydrocarbons methyl-(2-hydroxy-5-bromo-o-phenylstyryl) ketone and acetonitrile, in the presence or absence of acidic or (3-(2-hydroxynaphthyl-1)o-phenylvinyl ketone. basic condensing agents such as zinc chloride, phos 3,971,808 5 6 phoric acid, toluenesulfonic acid, boric acid, pyridine, Papers coated with this compound in microcapsules piperidine, triethylamine and ammonium acetate, in give a blue coloration when broken against an acid amounts as usually used for condensation reactions of reacting layer by a writing operation. this kind and under the usual condensation conditions. Advantageously, condensation is carried out attemper 5 EXAMPLE 3 atures ranging from 20 to 120°C. The ring closure to 94 parts of 2-methyl-3-phenylnaphthopyrylium tetra the pyran may take place at the same time as or subse chloroferrate and 43 parts of diethylaminosalicylalde quently to the condensation in the same or a separate hyde are heated in 800 parts of alcohol for 2 hours stage, optionally in the presence of bases such as so O under reflux. The dye thus formed is converted to the dium or potassium hydroxide or carbonate, sodium colorless compound 3'-phenyl-7-diethylaminospiro acetate, ammonia, aliphatic amines and pyridine, in 2H-1-benzopyran-2,2'-(2H)-naphtho-(2,1-b)-pyran) conventional manner. The crystallized spirodipyran in the manner described in Example 1. The yield is 54 compounds precipitated from the solution may then be parts and the melting point of the compound is used in known manner as dye precursors in copying 5 232.234°C. processes. When contacted with acid reacting substances, this For example, they may be worked into a paste which compound gives a blue coloration. is then coated onto paper and overcoated with a pro EXAMPLE 4 tective layer. A particularly advantageous method is to use the dye precursors in solution in a non-volatile or 20 47 parts of 2-methyl-3-phenylnaphthopyrylium tetra high-boiling solvent such as chloroparaffin trichlorodi chloroferrate and 2O parts of dime phenyl or one of the usual solvents such as toluene, and thylaminosalicylaldehyde are heated for 2 hours under to encapsulate the solution in microcapsules, with reflux in 400 parts of alcohol. The dye thus formed is which the paper surface is then coated. When this layer converted to the colorless compound 3'-phenyl-7- is pressed (for example by a writing operation) against 25 dimethylamino-spiro-2H-1-benzopyran-2,2'-(2H)- a surface which has been coated with an acid reacting naphtho-(2,1-b)-pyran) in the manner described in substance, blue designs (e.g. characters) are formed. Example 1, the melting point of this compound being The solutions of the 3'arylspirodipyranes of the inven 250°-252°C. tion show virtually no coloration when applied to nor The yield is 21 parts. When contacted with acid re mal paper. Thus no mirror image is produced on the 30 acting substances, this compound gives a blue color reverse side of the top sheet coated with the dye pre ation. cursor during the copying operation. In addition to this EXAMPLE 5 advantage, the spirodipyrans of the invention give char acters which are distinguished by particularly high strength and good photocopying properties. 35 In the following Examples the parts and percentages are by weight. EXAMPLE 1. 126 parts of 2-methyl-3-phenylbenzopyrylium tetra 40 chloroferrate and 65 parts of diethylaminosalicylalde hyde are heated for 2 hours under reflux in 900 parts of 3'-phenyl-6'-bromo-7-diethylamino-2,2'-spiro-di-2H alcohol. When condensation is complete, the solvent is 1-benzopyran). decanted and the dye is stirred in 100 parts of 25% 45 ammonia solution and 1,000 parts of benzene until it EXAMPLE 6 loses its color completely. The benzene phase is sepa rated, purified with animal charcoal, dried over sodium sulfate and concentrated to a volume of about 300 ck parts. 150 parts of ligroin are added to this solution to precipitate 74 parts of 3'-phenyl-7-diethylamino-2,2'- 50 spiro-di-2H-1-benzopyran) in the form of pale yellow crystals. The melting point of this compound is 140°-142C. When a solution of this compound in dodecylben zene is enclosed in microcapsules, which are then 55 coated onto the surface of paper, a blue coloration is 3'-phenyl-6'-chloro-7-dimethylamino-2,2'-spiro-di obtained, by a writing operation, when the capsules are (2H-1-benzopyran). broken and their contents come into contact with an acid reacting layer. EXAMPLE 7 60

EXAMPLE 2 42 parts of 2-methyl-3-phenylbenzopyrylium tetra chloroferrate and 20 parts of dime thylaminosalicylaldehyde are heated for 2 hours under reflux in 400 parts of alcohol. The 3'-phenyl-7-dime 65 thylamino-2,2'-spiro-di-2H-1-benzopyran obtained after working up as in Example 1 has a melting point of 57-159°C.

3,971,808 9 10 2. A spirodipyran as claimed in claim 1 of the for-- 5. A spirodipyran as claimed in claim 1 of the for mula mula

5

10

in which 15 A is a benzene or a (2,1-b)-naphthalene nucleus, or a benzene or a (2,1-b)-naphthalene nucleus substi tuted by one chloro, bromo, methoxy, ethoxy, car- wherein R' is methyl or ethyl. bomethoxy or carboethoxy, 6. A spirodipyran as claimed in claim 1 of the for R is phenyl or methylphenyl, 20 mula R is hydrogen, phenyl or alkyl of from 1 to 8 carbon atoms and R is methyl or ethyl. 3. A spirodipyran as claimed in claim 2, wherein Ris hydrogen, methyl, ethyl or phenyl. 25 4. A spirodipyran as claimed in claim 1 of the for mula

30

35 wherein R5 is hydrogen, carbomethoxy or carboethoxy and R' is methyl or ethyl. wherein R' is methyl or ethyl. ck k ck k k 40

45

50

55

60

65