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Патент USA US2411396

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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.
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