Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D239/00—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings
  • C07D239/02—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings
  • C07D239/24—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
  • C07D239/28—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to ring carbon atoms
  • C07D239/46—Two or more oxygen, sulphur or nitrogen atoms
  • C07D239/56—One oxygen atom and one sulfur atom
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
  • C07D233/04—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member
  • C07D233/28—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D233/30—Oxygen or sulfur atoms
  • C07D233/42—Sulfur atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
  • C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
  • C07D233/66—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D233/86—Oxygen and sulfur atoms, e.g. thiohydantoin
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D239/00—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings
  • C07D239/02—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings
  • C07D239/24—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
  • C07D239/28—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to ring carbon atoms
  • C07D239/46—Two or more oxygen, sulphur or nitrogen atoms
  • C07D239/60—Three or more oxygen or sulfur atoms
  • C07D239/66—Thiobarbituric acids
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/12—Electroplating: Baths therefor from solutions of nickel or cobalt
  • C25D3/14—Electroplating: Baths therefor from solutions of nickel or cobalt from baths containing acetylenic or heterocyclic compounds
  • C25D3/18—Heterocyclic compounds

Definitions

• the process of this invention comprises electrodepositing nickel from an aqueous nickel electroplating bath containing a secondary brightener and, as a primary brightener, an elfective amount of a cyanoethyl compound selected from the group consisting of cyanoethyl thiohydantoin, cyanoethyl Z-imidazolidine thione, cyanoethyl thiobarbituric acid, and cyanoethyl 2-thiouracil.
• a cyanoethyl compound selected from the group consisting of cyanoethyl thiohydantoin, cyanoethyl Z-imidazolidine thione, cyanoethyl thiobarbituric acid, and cyanoethyl 2-thiouracil.
• This invention relates to electroplating nickel and more particularly to the electrodeposition of bright nickel.
• Nickel electrodeposits as plated from Watts, high chloride, fiuoborate, etc. type baths are not bright when plated in thicknesses substantially greater than those of very thin strike or flash coatings. Such deposits do not increase in luster with increasing thickness but rather decrease in brightness until dull matte deposits are obtained.
• To obtain thick bright deposits from such baths it is necessary to add certain additives, commonly of organic nature, which assist in producing highly lustrous deposits with good rate of brightening. It is a common characteristic of such so-called bright nickel plating baths that the deposits tend to increase in luster with increasing thickness.
• a particular advantage of these bright nickel baths is that bright deposits can be obtained on basis metals which have not been polished or which do not have a high starting luster, within reasonable specification thickness of nickel.
• Other concomitant advantages such as leveling or the ability of the deposits to fill in pores,
• ⁇ scratches, or other superficial defects of the basis metal may also be obtained.
• Addition agents useful as brighteners in nickel plating baths are generally divided into two classes on the basis of their predominant function.
• Primary brighteners are materials used in very low or relatively low concentration, typically 0.002-02 g./l., which by themselves may or may not produce visible brightening action. Those primary brighteners which may exhibit. some brightening effects when used alone generally also produce deleterious side elfects such as reduced cathode efficiency, poor deposit color, deposit brittleness and exfoliation, very narrow bright plate range, or failure to plate at all on the low current density areas.
• Secondary brighteners are materials which are ordinarily used in combination with primary brighteners but in appreciably higher concentration that that of the primary brighteners-typica1ly 1 g./l. to 30 g./l. These materials, by themselves, may produce some brightening or grain refining effects, but the deposits are not usually mirror bright and the rate of brightening is usually inadequate.
• the rate of brightening and levelling may vary in degree depending on the particular cooperative additives chosen and their actual and relative concentrations. A high degree of rate of brightening and levelling is generally desirable, particularly where maximum luster is desired with minimum nickel thicknesses.
• the concentrations of the secondary brighteners may usually vary Within fairly wide limits. The concentrations of the primary brighteners must usually be maintained within fairly narrow limits in order to maintain desirable properties including good ductility, adequate coverage over low current density areas, etc.
• Any bright nickel system which can be rendered more tolerant to fluctuations in primary brightener concentrations will have obvious advantages, particularly sincethe low concentration of primary brighteners and the intrinsic chemical nature of some make strict control by chemical analysis difficult.
• a primary brightener which can be used over a wide range of concentration is of great value in bright nickel plating.
• the process of this invention comprises electrodepositing nickel from an aqueous nickel electroplating bath containing a secondary brightener and, as a primary brightener an effective amount of a cyanoethyl compound selected from the group consisting of cyanoethyl thiohydantoin, cyanoethylated Z-imidazolidine thione, cyanoethyl thiobarbituric acid, and cyanoethyl 2-thiouracil.
• a cyanoethyl compound selected from the group consisting of cyanoethyl thiohydantoin, cyanoethylated Z-imidazolidine thione, cyanoethyl thiobarbituric acid, and cyanoethyl 2-thiouracil.
• novel compounds which may be used in pratice of this invention may include cyanoethyl thiohydantoin, cyanoethyl Z-imidazolidine thione, cyanoethyl thiobarbituric acid, and cyanoethyl 2-thiouracil.
• Thiohydantoin (I) may be cyanoethylated as herein disclosed to produce 4-mono-13-cyanoethylthiohydantoin (II), 3,4,4 di-fl-cyanoethyl thiohydantoin (III), 3,4-tri-Bcyanoethyl thiohydantoin (IV), and 1,3,4,4-tetra-fi-cyanoethyl thiohydantoin (V):
• mixtures of compounds e.g. isomers, or mixtures of compounds which have been cyanoethylated to a different degree may be simultaneously formed; and these mixtures need not be separated for utilization as hereinafter set forth, because it may be found that these mixtures perform as well as pure compounds or pure isomers.
• Inertly substituted thiohydantoin derivatives such as l-acetyl-Z-thiohydantoin may also be cyanoethylated to produce e.g. monocyanoethyl l-acetyl- 2-thiohydantoin.
• the compounds When the composition is such (as is the case with the compositions of Formulae II-IV) that the tautomerism permits formation of the thiol from the thione, then the compounds may be soluble in water or dilute alkali due to formation of the thiol salt.
• Z-imidizolidine thione may be cyanoethylated, e.g. to produce 1,3-di43-cyanoethyl-24midazolidine thione (VII).
• cyanoethyl thiobarbitu-ric acid derivatives may include S-B-cyanoethyl-Z-thiobarbituric acid (X), 1,5-difl-dicyanoethyl-Z-thiobarbituric acid (XI), and 1,3,5,5 tetra-[i-cyanoethyl-Z-thiobarbituric acid (XII):
• Z-thiouracil may be cyanoethylated to produce 3-mono-p3-cyanoethyl Z-thiouracil (XIV); 1,3-di-(3-cyanoethyl Z-thiouracil (XV); 1,3,4-tri-B-cyanoethyl Z-thiouracil (XVI); etc.
• the reaction of the heterocyclic thiocarbonyl compound With acrylonitrile may be effected under relatively mild conditions.
• water may be used as a reaction medium.
• the reaction may be accelerated by use as catalyst of a proton acceptor such as a base such as sodium hydroxide, potassium hydroxide, or quaternary ammonium hydroxides such as benzyl trimethyl ammonium hydroxide or amines such as triethylamine.
• Reaction may be effected by mixing the components preferably in the presence of a reaction medium and preferably accompanied by vigorous agitation.
• the acrylonitrile may be present in the amount of 1-1.5 equivalent of acrylonitrile.
• the acrylonitrile may be used in amount of at least two or more equivalents. The position of the cyanoethyl groups may in all cases be readily confirmed by inspection of the infra-red spectrum of the compounds, by the Sodium Azide-Iodine test, elemental analysis, etc.
• the temperature during the reaction may be controlled to fall in the range of 0 C. to about 70 C.
• Lower temperatures e.g. 0 C.-35 C. favor lower degrees of cyanoethylation, while higher temperatures, e.g. 35 C.- 70 C. favor higher degrees of cyanoethylation.
• the time of reaction depending on the specific compounds reacted, may be from a few minutes, e.g. 5 minutes, to several hours. Commonly it may be 30-60 minutes.
• the excess of the acrylonitrile may be removed by distillation (by heating to C. or higher) or by distillation under vacuum at lower temperatures.
• Alkali-insoluble products such as tetracyanoethyl 2- thiohydantoin, will precipitate on removal of the excess unreacted acrylonitrile.
• Alkali-soluble products may be recovered by acidification with e.g. dilute sulfuric acid. In either case, the product may then be removed by filtration or decantation depending on whether it is crystalline or liquid. Further purification of crystalline product may be recrystallization from aqueous solutions or organic solvents or mixtures thereof. Purification of liquid products may be effected by fractional distillation, solvent extraction, etc.
• EXAMPLE 1 3,4-di-[3-cyanoelhyl-Z-thiohydantoin 125 g. water, 18 g. C.P. sodium hydroxide pellets, and 50 g. 2-thiohydantoin were mixed together and stirred magnetically. To the solution, there was added 35 ml. of acrylonitrile, drop by drop, over 25 minutes (starting temperature 35 C., final temperature 58 C.). Stirring was continued for another 40 minutes. The pH after cooling to room temperature was adjusted to 5.5 with dilute sulfuric acid 1:1 by volume) and a heavy crystalline precipitate formed. The product was filtered off, washed with water, and air-dried (50.0 grams)M.P. 192-194 C.
• EXAMPLE 2 3,4,4-tri-,8-cyanethyl-2-thi0hydantoin 50 g. 2-thiohydantoin, 150 g. of a water solution containing 18 g. sodium hydroxide were mixed together and magnetically stirred. 175 ml. acrylonitrile was added, drop by drop, over a period of 1 hour. The starting temperature was 32 C. It rose to a maximum temperature of 58 C. after which it was cooled. Final temperature was 45 C. Stirring was continued for 2.5 hours. The reaction mixture was then diluted to 500 ml. with water and the pH adjusted to 7.0 with dilute sulfuric acid 1:1 by volume). A heavy oily layer settled out.
• EXAMPLE 4 10 g. of 2-imidazolidine thione, 25 g. water, 4 g. sodium hydroxide, and 25 ml. acrylonitrile were mixed and stirred at room temperature. The temperature rose within 2 minutes to 90 C. Stirring was interrupted and reaction mixture cooled to room temperature. The oil which was formed gave a crystalline precipitate on stirring at room temperature. The precipitate was filtered, water washed, ether washed, and dried in a vacuum dessicator. The product gave a negative test with sodium azide-iodine reagent indicating that the two hydrogen atoms attached to the nitrogen atoms had been cyanoethylated. The product on recrystallization from water had a M.P. of 125C.-128 C. (Fisher-Johns). Yield was 5.3 grams (26.1%) of recrystallized product. The infra-red spectra showed presence of the thiocarbonyl group.
• Typical compounds which may be effective as primary brighteners in the novel nickel plating process of'this invention may include:
• the novel class of primary brighteners of this invention when used in combination with suitable secondary brighteners may give highly lustrous, brilliant deposits characterized by high rate of brightening and levelling, excellent receptivity for chromium plating, excellent low current density coverage, and relatively very low rates of consumption. It is possible to attain excellent ductility by control of concentration of the primary brightener as noted infra.
• the baths may be used with air agitation or mechanical agitation.
• the baths may be electrolyzed for relatively long periods without buildup of harmful decomposition products.
• the brighteners of this invention are also compatible with many secondary brighteners including those characterized by low cost e.g. benzene sul-fonamide.
• the primary brighteners of this invention may be used in concentrations of 0.002 g./l. to 0.050 g./l., the particular concentration chosen depending on: the particular types and concentrations of secondary and secondary auxiliary brighteners used, and also on such factors as the concentrations of nickel sulfate, nickel chloride, and boric acid; operating conditions with respect to temperature and degree of agitation; degree of luster, rate of brightening and levelling desired; and the finish of the basis metal. It is preferred to use between 0.004 g./l. and 0.020 g./-l.
• baths containing the novel primary brighteners may operate at pH of 3-4.5 with 3.54.2 preferred. All pH values herein are electrometric.
• Secondary brighteners (typically present in amount of l-4 g./l. and preferably 23 g./l.) which are useful with the primary brighteners of this invention may include aromatic sulfonates, sulfonamides, and sulfimides, or derivatives thereof such as orthobenzoic sulfimide (saccharin), benzene sulfonamide, m-benzene disulfonam-ide, o-sulfobenzaldehyde, and N,N-bis(phenylsulfonyl)-4,4- diphenyl disulfonamide, and dibenzene sulfonamide.
• aromatic sulfonates such as orthobenzoic sulfimide (saccharin), benzene sulfonamide, m-benzene disulfonam-ide, o-sulfobenzaldehyde, and N,N-bis(phenylsulfony
• auxiliary secondary brighteners such as olefinic or acetylenic aliphatic sulfonates, which may be necessary for optimum results when using some prior art primary brighteners.
• Typical baths and processes for electroplating bright nickel include those described in Principles of Electroplating and Electroforming, Blum and Hogaboom, pages 362-381, revised third edition, 1949, McGraW-Hill Book Co., Inc., New York; and in Modern Electroplating, edited by A. G. Gray, The Electrochemical Society, 1953, pages 299-355.
• the control and operating conditions, including the concentration of the bath ingredients, pH, temperature, cathode current density, etc., of these con ventional baths are generally applicable to the present invention.
• Practically all baths for electroplating bright nickel contain nickel sulfate; a chloride, usually nickel chloride; a buffering agent, usually boric acid; and a wetting agent, e.g.
• Such baths include the well-known Watts bath and the high chloride bath.
• Other baths may contain, as the source of the nickel, a combination of nickel fluoborate with nickel sulfate and nickel chloride, or a combination of nickel fluoborate with nickel chloride.
• Typical Watts-type baths and high chloride baths are noted in Tables II and III.
• Best plating results are usually achieved in the electrodeposition process when there is used a method of preventing the thin film immediately adjacent to the cathode from becoming depleted in cation content. This is desirably accomplished by agitation, such as by air agitation, solution pumping, moving cathode rod, etc. With increasing agitation at lower concentration of primary brightener may advantageously be used.
• an aqueous acidic nickel-containing bath was made up with the specified components. Electrodeposition of nickel was carried out by passing electric current through an electric circuit comprising a nickel anode and a sheet metal cathode, both immersed in the bath. The baths were agitated, usually by a moving cathode. Bright electrodeposits were obtained in all the tests included herein as examples.
• Nickel sulfate 300 Nickel chloride 60 Boric acid Sodium dihexyl sulfosuccinate 0.10
• the primary brightener is identified from Table I supra.
• the current density (CD) is expressed in ASD, amperes per square decimeter, and the pH is the electrometric pH.
• the primary brighteners of this invention may be particularly useful in plating deeply recessed articles. They have a very high tolerance to metallic contaminants such as zinc and copper, and can therefore be used in plating zinc-base die-castings which are a problem to plate using many prior art nickel brighteners because of their sensitivity to these metals as contaminants particularly in low current density recessed areas.
• the nickel electrodeposits obtained from baths utilizing the novel brightener combination are advantageous in that mirror-bright lustrous electrodeposits having a high degree of ductility are obtained over a wide range of cathode current densities.
• the bright nickel electrodeposits are preferably plated on a copper or copper alloy basis metal. However, they may be electrodeposited directly on such metals as iron, steel, etc.
• An aqueous acidic electroplating bath for electro plating nickel containing a secondary brightener and as a primary brightener an effective amount of a cyanoethylated compound selected from the group consisting of cyanoethyl thiohydantoin, cyanoethyl Z-imidazolicline thione, cyanoethyl thiobarbituric acid, and cyanoethyl 2-thiouracil.
• a cyanoethylated compound selected from the group consisting of cyanoethyl thiohydantoin, cyanoethyl Z-imidazolicline thione, cyanoethyl thiobarbituric acid, and cyanoethyl 2-thiouracil.
• An aqueous acid electroplating bath for electroplating nickel containing a secondary brightener and as a primary brightener an elfective amount of cyanoethyl thiohydantoin.
• An aqueous acidic electroplating bath for electroplating nickel containing a secondary brightener and as a primary brightener an effective amount of cyanoethyl 2- imidazolidine thione.
• An aqueous acidic electroplating bath for electroplating nickel containing a secondary brightener and as a primary brightener an effective amount of cyanoethyl thiobarbituric acid.
• An aqueous acidic electroplating bath for electroplating nickel containing a secondary brightener and as a primary brightener an effective amount of tricyanoethyl 2-thiohydantoin.
• An aqueous acidic electroplating bath for electroplating nickel containing a secondary brightener and as a primary brightener an effective amount of 3,4,4-tricyanoethyl 2-t-hiohydantoin.

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• Chemical Kinetics & Catalysis (AREA)
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Citations (4)

• 1964
  • 1964-05-01 US US364278A patent/US3341433A/en not_active Expired - Lifetime
• 1965
  • 1965-04-22 GB GB17106/65A patent/GB1111084A/en not_active Expired
  • 1965-04-22 GB GB37814/67A patent/GB1111085A/en not_active Expired
  • 1965-04-26 DE DE19651496910 patent/DE1496910A1/de active Pending
  • 1965-04-27 CH CH578965A patent/CH471232A/de not_active IP Right Cessation
  • 1965-04-29 NL NL6505514A patent/NL6505514A/xx unknown
  • 1965-04-30 ES ES0312467A patent/ES312467A1/es not_active Expired

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