Патент USA US2411396код для вставки
Patented Nov. 19, 1946 2,411,396 1 uNlE' STTES _ ENMT .' 2,4113% ' ‘ REACTION rnonuc'rs 0F Foamtnnnm AND SODIUM CYANAMIDE , ~ Joseph Frederic Walker, Lewiston, N. Y., assignor - to E. I. du Pont deNemours & Company, Wil mington, Del., a corporation of Delaware ‘ No Drawing. Application October 21, 1943, Serial No. 507,182 (Cl. 260-69) 9 Claims. 1 . This invention relates to certain new and val when dry, it undergoes further resini?cation uable products secured by reacting formaldehyde with sodium cynanamide. More particularly, it when heated in the moist state and should be dried quickly and at relatively low temperatures is concerned with the preparation of formalde . to avoid undesirable alteration. _ On long heating hyde-sodium cyanamide condensation products in the moist state it combines with additional by reacting the two chemical compounds in an aqueous solution, the temperature being main water and tends to liberate ammonia. , A sample heated-in this way was found to have an empiri tained at room temperature or below, and the re action being carried out under alkaline condi- - cal composition corresponding to CcHiaNsOa. The new product, dissolves readily in dilute tions. _ I 10 aqueous acids or strong alkalis and is practically .It is therefore one of the objects of this invention to prepare novel condensation products by reacting formaldehyde and sodium cyanamide. insoluble in Water. the product being least Solu ble in aqueous liquids having a pH of 8.0-9.0. When dissolved in aqueous alkalies or acids it Another object of this invention is to prepare may be ‘precipitated- therefrom, although the these products, valuable as electroplating addi- l5 yields upon reprecipitation are not entirely quan tion agents and for other purposes, by carrying titative.' Analyses of the reprecipitated product out the reaction in a reaction medium which is indicate that its composition is substantially un substantially alkaline in reaction. changed- These and ' still further objects of my invention will be apIn carrying out the reaction solid sodium cy-1 parent from the ensuing disclosure of certain 20 anamide is preferably added to an aqueous solu preferred embodiments thereof. ' tion of formaldehyde at a temperature some I have now found that a condensation product of sodium cyanamide and formaldehyde can he obtained in fair yields by the addition of sodium what below room temperature. The tempera ture will tend to increase during the reaction, and cooling will be necessary. The temperature of cyanamide to fairly cold aqueous, formaldehyde 25 the reaction mixture should be maintained gen solutions, and that it may be isolated as a watererally within the range of 15-20° 0. although tem insoluble precipitate by neutralization of excess peratlllfes as elevated as'35° C. if maintained for alkalinity in this solution. The reaction iscar- , only Short periods of time are not objectionable. ried out under alkaline conditions at a tempera- . I have found a temperature as high as 25° C. ture below 35° C., preferably. in the‘ range 15° to 30 maintained for some length of time not objec-, 20° C. At the end of the reaction period the tionable. When the acid added to precipitate product may be precipitated by the addition of the reaction product is added in successive por sui?cient acid to reduce the high alkaline pH of tions, or When it is added in Small increments the mixture to a'value vin the pH range 3 m9, over the entire reaction period, or over substan The product is probably a partially hydrated 35 tially the entire reaction period, it is not neces polymer of methylene cyanamide (CH2=NCN) in sary to restrict. the upper temperature limit so which approximately two-thirds of the CN radicarefully during-the latter stages of the process, cals have been converted to amide groups‘. and' somewhat more elevated temperatures can Analyses for carbon, hydrogen, and nitrogen inbe maintained without interference with the re dicate that its composition closely approximates to action- Ordinary commercial aqueous solutions the empirical formula, CsHroNcOz. The characof formaldehyde c0ntaining~37% of CH20 may be teristics of the product are those of an amorphous utilized directly, 01' ‘they may be diluted to $0111 resin, and it is probably not a simple compound of tions of approximately 20% CHzO concentration low molecular weight but rather a polymer or or less before being utilizedinthe reaction. mixture of polymers made up of units. eorre- 45 . When the reaction is carried out at approxi sponding to the CsHzoNeOz formula. It is bemately room temperature it is substantially 60m lieved that the structural formula of this polymer plete at the end of about four to six hours. A unit is as follows: mineral acid such as hydrochloric aciicll, sulfuric acid, phosphoric acid, or any other fa ly strong CONE’ ON CONE’ 50 acid, for example acetic acid, may then be added *CHPN_CH=_N_CHQ_N_ > The new condensation product is a white, ap- in amount su?icient to adjust the pH of the re- ‘ action mixture to one approximately within the parently-non-crystalline solid which chars when v range of 8.0-9.0. heated to temperatures above 300° C. Although . sodium cyanamide condensation, product to pre This causes the formaldehyde it is apparently stable when heated below 300° C. 55 cipitate. If desired, the hydrochloric acid or 2,dll,896 4 of time may be utilized without danger of objec tional resini?cation. The dried product was of a granular character and of a light brown color. The yield was approximately 65% of theory to the formaldehyde, or it may be added more on the basis of the assumed reaction given be or less continuously in small incremental amounts low. This amounted to approximately one-half during the entire reaction period. Under these pound of product per pound of technical 94% so-‘ conditions the reaction of sodium cyanamide and dium cyanamide used. Although I have not de? formaldehyde takes place concomitantly with the nitely established the chemical nature of my neutralization of the alkali. As previously stated, the addition of the mineral acid portion v10 product, which is believed to be a mixture of poly mers having the composition previously given, wise, or continuously during the reaction, also I believe that the reaction which takes place is has the advantage of permitting the maintenance as follows: ' of temperatures somewhat above‘ 25° C. during other mineral acid may be added in successive small portions at various stages of the reaction following the addition of the sodium cyanamide the latter stages of the process without interfer ence with the reaction, thus simplifying the prob 15 lem of cooling the reaction mixture. This reaction evidently takes place in two The solution containing the precipitated con stages: (-1) condensation of sodium cyanamide. densation' product may now be allowed to stand and formaldehyde and. (2) ‘neutralization of for two or more hours, or overnight, to insure complete precipitation. The ?ltered product may 20 alkali'with resultant precipitation of ?nished product. Each stage of the reaction is exother then be washed with water, dried, ground, and‘ packed. I have secured very satisfactory drying with only slight discoloration, and with no cak ing, sintering or charring of the condensation mic. ' Other suitable modi?cations and changes as will be obvious to a skilled chemist may be made product, by the use of a current of warm air 25 in carrying out my process, without departing from the spirit or scope thereof. The scope of at a temperature of 80 to90° .F. However, drum my invention is accordingly intended to include drying on a heated rotating drum has also given ~ these variations and modifications, to the extent very satisfactory results. The‘dried product usu that they are comprehended within the scope ally tends to have a reddish or brownish cast 30 ofthe appended claims. unless vacuum dried at room temperature. I claim: I The new condensation product is valuable as l. The process of preparing condensation an addition agent in electroplating baths, and is also believed suitable for use as a flame-proo?ng agent. in the manufacture of heat-resistant res products of sodium cyanamide‘ and formaldehyde chloric acid was added continuously at a rate of about 12 lbs. per hour until the pH ‘of the reaction mixture had fallen to a value in the precipitating said condensation product. which comprises reacting, as the sole reactants, ins, and in the case-hardening of ferrousmetals. 35 said compounds in substantially equimolar pro portions in an aqueous alkaline reaction medium As an example of my process for preparing having a pH above 9 and approximately the pH the formaldehyde-sodium cyanamide condensa .of said aqueous solution of equimolecular propor tion product, the following may be. given: tions of sodium cyanamide and formaldehyde, Sodium cyanamide (technical grade approxi mately 94%) in the amount of 17.9 lbs. was re 40 the temperature during said reaction being main tained below about 25° C. ‘ acted with 16.1 lbs. of commercial 3'7 % formalde 2. The process of preparing condensation hyde solution. The solid sodium cyanamide was products of sodium cyanamide and formaldehyde added to the formaldehyde solution, which was which comprises reacting, as the sole reactants, contained in a 15~gallon stoneware crock equip ped with a stainless steel cooling coil and a 45 said compounds in substantially equimolar pro portions, at a temperature not exceeding 35° C. stainless steel propeller agitator. Before the ad in an aqueous alkaline reaction medium having dition of the solid sodium cyanamide in granu a pH above 9 and approximately the pH of said lar form the formaldehyde was cooled to about aqueous solution of equimolecular proportions 5° C. by the addition of ice to the solution. The granular sodium cyanamide was added gradually, 50 of sodium cyanamide and formaldehyde, and adding to said reaction a mineral acid in suffi ‘ in successive small increments, ice being added cient amount to adjust the pH of said reaction duringr the addition to keep the temperature be . mixture to one within the range 3.0-9.0, thereby‘ 1ow~about 20° C. Following this, 23% hydro 3. The process of preparing condensation products of sodium cyanamide and formaldehyde which comprises reacting, as the sole reactants, said compounds in substantially equimolar pro range pH 8-9. Approximately ‘62.9 lbs. of 23% acid were required for this purpose. The tem portions in an aqueous alkaline reaction medium perature of the reaction mixture was maintained in the range 15 to 20° C. throughout this period, 60 having a pH above 9 and approximately the pH of said aqueous solution of equimolecular pro precipitation of_ product occurring during addi portions of sodium cyanamide and formaldehyde, tion of the last half of the acid. cooling said reaction medium during said reac The precipitate was in a ?nely-divided form tion so that the temperature does not exceed, 25° and was white or colorless. The reaction mix ture was allowed to stand overnight before ?ltra 65 C., and adding a mineral acid in su?icient amount to insure a pH of said reaction medium tion in order to insure complete precipitation of within the range 8.0-9.0 at the conclusion of the the product. The condensation product was then ?ltered off, washed thoroughly with water ' reaction, whereby said condensation product is precipitated. and dried with hot air at a temperature of 4. The process of preparing condensation prod 80-100° F. This temperature was employed in 70 ucts of sodium cyanamide and formaldehyde the drying since at higher drying temperatures which comprises reacting,- as the sole reactants, there is danger that the product may cake to said compounds in substantially equimolar pro form a brittle, dark red or reddish brown resin. portions, ‘at a temperature not exceeding 35"‘ C. Drum drying using a heated rotating drum on which the product remains for only a. short period 75 in an aqueous alkaline reaction medium having 2,411,sae pH above 9 and approximately the pH _of said mineral acid in amount su?lcient to adjust the pH of the reaction mixture to one within the ueous solution of equimoleciilar proportions range 8.0-9.0, and recovering the precipitated sodium cyanamide and formaldehyde, and condensation product. from said reaction mixture. ding hydrochloric acid thereto in amounts suf 7. The process which comprises adding, in‘ :ien't to insure a pH of said reaction medium substantially equirnolar proportions, solid sodium ' thin the range 8.0-9.0 at the conclusion of the cyanamide to an aqueous solution of formalde action, whereby said condensation product is hyde to form a reaction mixture in which said ‘ ecipitated in said aqueous reaction medium. two substances are the sole reactants, maintain 5. The process of preparing condensation prod ing the temperature of the resulting reaction :ts of sodium cyanamide and formaldehyde mixture below about 25° C. and at a pH above aich comprises reacting, as the sole reactants, 9 and approximately the pH of said aqueous solu id compounds in substantially equimolar pro tion of equimolecular proportions of sodium cy »rtions in an aqueous alkaline reaction medium anamide and formaldehyde, adding hydrochloric wing a pH above 9 and approximately the pH said aqueous solution of equimolecular propor 15 acid thereto in amount su?icient to adjust the pH of said reaction mixture to one within the ms of sodium cyanamide and formaldehyde, range of 8.0-9.0, and recovering the'precipitated cling said reaction medium during the reaction sodium cyanamide-formaldehyde condensation that the temperaturedoes not exceed about product from said reaction mixture. ‘»° C., and adding hydrochloric acid thereto in 8. The condensation product of sodium cyana nounts sumcient to insure a pH within the 20 mide and formaldehyde obtained by the proc nge of 8.0-9.0 at the con'clusion of the reaction, ess of claim 1 having the empirical formula hereby the desired condensation product is pre pitated in said reaction medium. . CsHroNeOz, said product being a white, apparently I non-crystalline solid, practically insoluble in wa antially equimolar proportion, solid sodium 25 ter, but readily soluble in aqueous alkalies and 6. The process which comprises adding, in sub acids. ~ 'anamide to an aqueous solution of formalde 9. The product prepared by reacting sodium vde to form a reaction mixture in which said cyanamide and formaldehyde in an aqueous alka vo substances are the sole reactants, maintain line reaction medium in accordance with the ig the resulting reaction mixture at a tempera lre below about 25° C. and at a pH above 9 30 process of claim 2, and adding a mineral acid 1d approximately the pH of said aqueous solu on of equimolecular proportions of sodium cy namide and formaldehyde, adding thereto a to said reaction medium in amount su?icient to precipitate said product in said reaction medium. JOSEPH FREDERIC W.