US2330791A

US2330791A - Method fob the preparation of alpha

Info

Publication number: US2330791A
Authority: US
Publication date: 1943-09-28
Anticipated expiration: 1960-09-28

Description

Patented Sept. 28, 1943 UNITED STA 2,330,791 s PATENT OFFICEI METHOD FOR, THE PREPARATION OF ALPHA NABHTHOSELENAZOLES Edmund B. Middleton, Woo'dbridge, and George A.

. Dawson, Stelton, N. .L, assignors, by mesne assignments, to E. I. du Rent de-Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application June 3, 1940,

Serial N0. 338,556 l 7 Claims. (Ci. 2601 -258) This invention relates to alpha naphthoselena zoles, more particularly Z-hydrocarbon alpha naphthoselenazole, and a method forthepreparation thereof,

I This application is a continuation-impart of 78,734,1"1led.

our copending application Serial No. May 8,. 1936.

Among theobjects of the invention are manufacture f alpha naphthoselenazoles, more particularly 2-hydrocarbon alpha naphthoselena zolesof high purity in good yieldsby aseries of reactions which proceed rather smoothly with a minimum of side reactions andat an economicah cost. These objects have not heretofore been.

The alpha napl1tl1oselenazoles,;and especially the 2-alkyl alpha naphthoselenazoles,. are, very. I,

salt with a selenocyanate in the-presence of an oxidizing, agent; (2) heating the resultant product with a strong hydrolysing agent; and. (3) treating thehydrolysisproduct with an acylating agent. The/final product may be recovered in any convenient manner. l

Thehseries of reactions in question starting with ,beta naphthylamine may-"be carried out in several different ways, as. follows;

A. The beta naphthylamine is converted in a well: known manner to al-halogenmZ-amino naphthalene salt. The amine saltlof the '1 ,halogeno-2-amino naphthalene is then reacted with aselenocyanate, preferably analkali metal selenocyanate such as potassium selenocyanate. The reaction product is preferably made alkaline with ammonia. The resultant product is then hydrolysed, preferably by treatment witha strong alkaline solution such as a solution -of sodium hydroxide or potassium hydroxide. The resultantproduct obtainedv upon hydrolysis is then preferably oxidized, for example, by treatment with a dilute hydrogen peroxide solution. The oxidation product is preferably separated. It is then reduced and reacted with an acylating agent.

Thismaybe accomplished, for examp1e,"by carryingout the reaction with acetic anhydride in the presence of metallic zinc, thereby'producing a Z-methyl alpha naphthoselenazole.

pose should preferably be substantially inert to the free halogen. The solvent employed should also preferably be a solvent for both the beta naphthylamine} and the selenocyanate. although this.is,not-absolutely essential. Itshould preferably be nonraoid since acid solvents precipi tat e selenium: from certain selenocyanate comm, pounds. It is,ordinarily preferable to employ a mixture of solvents because it has been found that. in most instances one'solvent does not give the desiredresults, Alcohols, such as, for example, ethyl alcohol, are common solvents for both beta naphthylamine and selenocyanates such as the alkali metal selenocyanates. These: alcohols, ho-wevenare halogenated by free halogens such as bromine. This'halogenation may besubstantially avoided byemploying. a mixture of $01- vents such as,,for example, a mixtureof an alcohol and sme ma solvent substantially inert to halogen.. Mention rnay be made particularly of .mixtures of alcohol with halogenated hydrocar bons, 'e. g. chloroform and/0r carbon tetrachlo ride.

' tion. .The product thus obtained is then reduced The product obtained is preferably treatedwit ammonia. The resultant product is then hydrolysed. with a strong alkaline solution. It may be isolated from the alkaline solution byoxidaand reacted with an acylating agent to produce a 2-hydrocarbon alpha naphthoselenazole.

C. The betanaphthylamine is reacted directly with cupric selenocyanate inthe presence of a solvent. The reaction'product is extracted as a salt by treatment with a mineral acid. Treating the salt solution with ammonia precipitates the free base. The resultant productis then hydrolysed and the hydrolysis product is preferably isolated by oxidation, for example, with hydrogen B. The beta naphthylamine and-a selenocy anate in a suitable solvent are treated with a peroxide. Thefproduct thus isolated is then reduced and reacted with an acylating agent to produce a 2-hydrojcarbfon alpha naphthoselenazole. I

"The 2-hydrocarbon alpha ,naphthoselenazoles thus produced havev the following general formula:

in'which R represents a naphthalene nucleus, Se represents a selenium atom attached to an alpha position of said naphthalene nucleus, N represents a nitrogenatom attached to an adjoining beta position of said naphthalene nucleus, C represents a carbon atom between said selenium atom and said nitrogen atom, and R1 represents hydrogen or a" hydrocarbon group; for example, an

5 alkyl group, as methyl, ethyl, propyl, or the like;

aryl, as, phenyl, tolyl, xylyl, naphthyl, diphenyl,

free halogen. A suitable solvent for this purthe particular acylating agent employed in carrying out the reactions described. For instance; in order to produce a Z-methyl alpha naphthoselenazole, acetic anhydride'is used*,"lorzacetyl" chloride. To produce a 2-ethyl alpha naphth'o selenazole, propionic anhydrideor propionyl chlo'-- ride is used. In order to produce 2'-:hydrocarbom2 aalpha naphthoselenazoles havinga great-er or lesser number of carbon atoms; an acylating agent is employed appropriate to the number of carbonatoms desired. For instance; the -lauryl" or the like;- aryl' alkyl,=.as; benzyl; cinnamyl. The nature of the hydrocarbon groupiwill depend upon of alcohol was treated with: 28 parts of potassium selenocyanate-in 80 parts of Water. After standing over night at room temperature, the mixture was evaporated to dryness and extracted many times with hot water. The extract was made alkalineswith ammonia and the aminonaphthoselenazol'e precipitated. It was recrystallized from alcoholi Yield 36 parts; M. P. 252 C. This compound has the formula:

derivative may be produced by using lauroyl chloe ride as the acylating agent. The phenyl derivative may be produced by using benzoylchloride as the acylating agent; and thecinnamylderiva tive' 'may lee-produced by employing cinnamoyl.

chloride asith'e' acylating agent. Similarly other acylatingagents of' the type described are-zem' The radical R may contain isubstituentgroup's-.-= Among such groups -are; for example, halogen (ea g.-chlorine, bromine; iodine; fluorine)"; alkyl (e. g. meth yL ethyl, propylg butyl i and higher homologues) and alkoxy (e: g: methoxy', ethoxy and higher homologues); It is essentiaL-however, for the" purpose of the present inventionthat the starting-"material be a beta naphthylainine in whichthe-alphaposition which is eventually-to belinkedtoa selenium atom be eit'her unoccupiedor occupi'edby ahalogenatom.-- The'betapo'si ti'on-will naturally be occupied by an" amino group; It has been found 'thatbyusing' these starting-'materials-and proceeding inthe manner described difficulties are avoided which ordinarilyare encountered in other proposed-processes such as -those "involving the; use'of alpha naphthyl amineas a startingmaterial followed by nitra tion, diazotization, etc.

The compounds given in-Formulalare refrred" to herein" as' the' 2-h'ydrocarbon' alpha naphthoselenazolebases.' These bases react withv organic esters of organic and-inorganic "acids"to form"quaternary amnronium salts. Among the esters'whichmay'be reacted .with these bases in" order to produce such" quaternary ammoniumsaltsare; for example; methyl chloride; ethyl chloride'and higheralkyl homologues, methyl dyes, dicarbocyanine dyes and other types of dyes.

Many of these dyes are useful in'making phot'o-.

graphic emulsions, particularly'as SBHSitlZGISJlII' such emulsions. The carbocyanine dyes are es-=' pecially valuable as green blind red sensitizers; that is to say, they sensitize in the red region of the spectrum but for photographic purposes are substantially insensitive in the green reg-ion of the spectrum.

The inventi'on will be further illustrated but is not-=limited by the followin'g examples in which"; 70

- bined ifiltrateszwere :neutralizedmwithii ammonia and: thee aminonaphthoselenazole precipitated; TheoVeraILyield was substantially lower than in the quantities are stated in parts by weight;

7 Example .I

A solution of 51 parts of..the.hydrochloride of 1 bitomo-Z aminonaphthalene in. about. 70 parts I ployed=t'o;pnoduce other aipha naphthoselenazoles.

mixture .aofv 28iiparts1: of: the aminonaphthoselenazol'c; 28 parts ofsodium hydroxide and 50 parts of water washeated together in a-nickel crucibla-for-three hours on an electric hot plate.

Theizcoverrof the crucible was adjusted so that steam could escape. Water lost by evaporation wasreplacedas it boil'ed off. Finally the crucible was evaporated to dryness and heated untilthe fum'es dueto -decomposition' began to appear.

llie r'esidue wastakem up with water and filtered. The filtrate wasfcooled.and dilute hydrogen peroxide added drop b'y -dr'op'until' no more precipitation =formed? The precipitated diselenide; a

i yellow amorphous powder, was separated by filtratioirawashed and"'dri ed;f A- yield -of 13 parts was obtained? This compound has the formula:

This was heated-toboiling in-108 parts of acetic anhydride i-underra reflux condenser "and '4 parts of zincgraduallyiaddeds Heating was. continued fonthirty:minutes-.- The hot solution was filteredfromsome-unreacted zinc; and poured'into water.

The solution. was laterextractedtavith ether; and

after :dryingethe V ether solution and removing the i ether-z by;- evaporation,.: needle crystals of the I 2 methyl alpha naphthoselenazolefi were obtained;: -It melted\ at Z81 F829a Yield -7'-parts.

On heating thecrude-material;with'three timesthe calculatedrquantity ofxethyl iodide under reflux:foretwenty.-four .hours and Jthen evaporating Example II 3 withn47-.8 DaItSJOfLCUDI'iC :selenocyanate.: After heatingzunder. airefiuxicondensenfor fifteen minutes-.:about:30-.pants of :33% .Hl'.vvereadded and the: heating was.:continueddforrfifteen. minutes longer: Thezsolution: wascfilteredihbt and the residue washedaweil:iwithihot waterx. The com Example I. The-.compound:-.was .converted to methybnaphthoselenazole-as in ExampleI.

, Example III I Twenty-five (25) parts of beta'-jnaphthylamine and 13.8 parts of potassium selenocyanate were dissolved in about '80 parts "of alcohol[ in a 3-necked flask, equipped with a stirrer. The temperature was'fkept below 25 C. while. a solution form was'added dropby drop. The flaskwa'sthen allowed to staiid at room temperature for several lioursafterwliich it was brought to a boil for arninut'e and then 'allowed' 'to stand at room temperature fontwelve hours. The solution was diluted with several volumes of cold water and oil separated which on standing deposited creamcolored crystals. These were filtered and recrystallized from alcohol, about 7.5 parts of 1 rri j v .f .Ewample IV carbricyanine dye was obtainedras follows: One-r1) "part of the- 'ethiodidemade "as de- I scribed inExample I and 6 parts of dry pyridine and about 1 part of ethyl orthoforinate were heated-under reflux for twentyminutes. An intense blue color developed)" On cooling, the dye was obtained as beautiful greenish-gold crystals. This dye, sym-3 3' -diethyl-naphthoselenocarbocyanine iodide, has the structure CzHs It is a red sensitizer for a photographic emulsion. When dissolved in alcohol and added to a negative emulsion, it conferred extra sensitivity with maximum at approximately 665: m. u. and extending to 700 m. u. g

In a manner similar to that described in Examples I, II and III, other. Z-allzyl-naphthoselenazoles and their quaternary salts may be prepared. For instance, the naphthalene nucleus may contain non-reactive substituents, e. g. alkyl (methyl, ethyl, propyl, and higher homologues) or alkoxy radicals (methoxy, ethoxy, and higher homologues) in one or more of the 3-, 4-, 5-, 6-, 7- or 8-positions. It will be understood, of course, that the ring closing positions of the beta naphthylamine initially employed must be free of substituents. The expression beta naphthylamine in the form of a salt is intended to include and cover an amine salt of beta naphthylamine either as pre-formed or as formed in situ during a reaction. In carrying out the first step of the reaction using an alkali metal selenocyanate, a non-acid medium is preferably employed because it has been found that the presence of an acid causes the precipitation of selenium. It will be understood, however, that if the beta naphthylamine is present as amsalt, it is substantially non-acid. The reaction between the salt of the beta naphthylamine, as, for example, a hydrohalide salt, and an alkali metal selenocyanate, as, for example, potassium selenocyanate, results in the elimination of an alkali of 28 parts ofbromine in about 45 parts of chlorohydrolysing base.

metal halide and in the formation of a selenourea which may be isolatedfor purification if desired. In the presence of an oxidizing agent the formation of the seleno-urea is apparently merely transitory and the product immediately obtained is a Z-amino alpha 'naphthoselenazole. The oxidizing agent may be a halogen atom which is already attached to the naphthylamine nucleus adjacent the amino group, as in Example. I, or it may be a free halogen added contemporaneously or simultaneously, asin Example II. In either event a ring closureoccurs. .Other oxidizing agents may be employed inthis step of the process, as, for instance, potassium ferricyanide, hydrogen peroxide, or potassium, permanganate. The salt, of Z-amino alpha naphthoselenazole will ordinarily separate directly and if desired may beemployed directly in the second or hydrolysis step of the process. It is ordinarily preferable, however, to convert this salt to the freebase by neutralization with ammonia .or some other non- In carrying out the first step of the process any known selenocyanate may be used, although the alkali metal selenocyanates are preferred, e. g. sodium and potassium seleno-- cyanatesa If cupric selenocyanate is employed, it is preferabletouseit in an organic solvent; For this purpose glacial acetic acidmay be used, although other solvents may be employed. i

i In carrying out the secondstep of;the process,

any-strong hydrolysing agent may be employed,

dium,

for example, solutions. of sodium hydroxide, potassium hydroxide or mixtures thereof. The hydrolysis actioncauses the selenazole ring of the Z-amino .alpha naphthoselenazole to be broken, thereby forming a selenonaphthol, .The selenonaphthol may be reacted directly with an acylating agent as, for example, an acid anhydride or an acid halide of the types previously mentioned. In this event a substantial excess of acylating agent will be required in order to neutralize the akaline hydrolysing agent which is still present.

For this reason and in order to further purify the intermediate product before carrying out the final step, it is often desirable to oxidize the selenonaphthol to a diselenide, which can be separated as such and purified. This may be accomplished by hydrogen peroxide, air, oxygen, or other oxidizing agents. If the selenonaphthol is oxidized to the diselem'de, the latter must be again reduced to the selenonaphthol before reaction with the acylating agent will take place. This reduction is accomplished by the use of nascent hydrogen, or any other suitable reducing agent. It maybe accomplished, for example, by adding metallic zinc to an acid acylating medium. The use of an acid halide, as, for example, an acid chloride as the acylating medium is particularly desirable because it can be added directly to the hydrolysis reaction product without requiring a large excess to neutralize the alkali present. This also results in the elimination of the diselenide formation step where the purpose or" this step is to eliminate the alkaline medium.

Having thus described the invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. In a method of making a 2-alkyl alphanaphthoselenazole, the series of steps which comprises (1) reacting beta naphthylamine in an acid solvent medium with copper selenocyanate, (2) heating the reaction mixture in an acid me- (3) neutralizing the resultant reaction mixture with ammonia and separating the precipitate, l) heating said precipitate with a strong Y alkaline hydrolysingcagen-t: v(5) treating theihye' drolysisiproductwith. an oxidizing agent and separating .the-V precipitategw) heating saidprecipitate with a' lower aliphatic "carboxylic. acid anhydride in the presence-of. nascent hydrogen and separating the -resultant -2-'alk yl alpha naph- V thoselenazole; t v

2. In a method of making; 2-methy1'- alpha naphthoselenazoles; the seriestof steps which comprises (1) reacting beta naphthylaminewin glacialiaceticlacid with copper selenocyanate; v(2) refluxing :the ireacti'onsmixture with hydro-- chloric acid; (3 neutralizing withr am-monia and 2 separating the resultant precipitate, .(4 heating. said precipitate with a strong caustio alkali solution, (5) treatinglthe resulting -iproduct'iwith an. oxidizing agent and separating the precipitate;

6) heating said precipitate acetic: 8111 1137: dride in the presence of zinc and. separating the resultant 5 Q-methyl alpha naDhthoselenazole;

3; In amethod of making ay;2-a1kyl alpha naphthoselenazole, the series of steps which comprises (1) a contemporaneously" reacting beta naphthylamine, an alkali metal selenocyanate and afree halogen and heating the reaction mixture, (2) neutralizing and-separating the precipitate, (3) heatingthe precipitate with a strong alkalinehydrolysing agent; v(4) treating the hydrolysis product with an oxidizing l agent andseparating the resultant precipitate; and (5) heating said precipitate with-a lower.- aliphatic carboxylic' acid anhydride inthe presence ofo nascent hydrogen.

tion, (5) treating therhydrolysis product with hydrogenrperoxide and separating the precipitate; (6)" heating said precipitate withaceti'c anhydride1n .the presence of zinc and separatmg the 2:-methy1.a1pha naphthoselenazole."

51The"m'eth'od' of preparing 2-"alkyl-a1phanaphthoselenazoles which comprises treating a betanaphthylamine in -the form of a salt with a' selenocyanate "under oxidizing conditions, hydroly'zing"thepxidation product with'an alkali; oxidizing the hydrolysis product; v.treatir'ig' the insoluble oxidation product with 'an acylating' agent and reducing it with nascent hydrogen;

6. .In a. method. of making aZ-a'llyl-alphanaphthoselenazole; theiserie's 'ofsteps which comprises treatinga beta'naphthylamine'in the form of a salt witlfa metallic, selenocyan'ate 'in'th'e presence of'a" free halogen and inth'e presence of "a substantially. non-acid. organic solvent which issubsta'ntially inert to the free halogen, toform' a ZQamino alpha-naphthoselenazole; heating the 2famino-a1pha naphthoselnazole with a strong hydrolyzing' agent,"cxidiz'in'g the hydrolysis product, reducing the insoluble oxidation product with" nascent hydrogen, and adding an 'acylating agent.

'7. In method: of making" a 2-alky1-alphanaphthoselenazole, the seriesof steps which comprises treatinga beta'naph'thylamine in the form of a salt and unsubstituted-in the alpha position with a metallic selenocyanate and 'a freehalogen in a mixture vof substantially, non-acid organic solvents, at least one of said solvents being a common solvent-for bot-h the-beta naphthylamine and the selenocyanate andanotherbeing a-solvent for said free halogen and substantially inert thereto, to form a 2-amin0-alpha-naphthoselenazole, heating the" 2-amino-alpha-naphthoselenazole with-a strong hydrolyzing agent, oxidizing the hydrolysis product} reducing the insoluble oxidation product with nascenthydr'ogen, and treating with an acylating agent. I

EDMUND B. MIDDLETON. GEORGE A. DAWSON.