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Патент USA US2127147

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Patented Aug. 16, 1938
John V. Vaughen, Lakewood, Ohio, assignor, by
mesne assignments, to E. I. du Pont de Ne
mours & Company, Wilmington, DeL, a corpo
ration of Delaware
No Drawing. Application April 24, 1935,
Serial No. 18,010
16 Claims. '(Ol. 148-.-8)
This invention relates to the modification of maldehyde, for‘ instance, when treated according
the action of acids on metals, and is particularly
directed to processes and compositions which em
ploy, in conjunction with an acid, an inhibitor
5 comprising unsaturated aldehyde-ammonium sul
?de resin.
Pickling and metal cleaning operations fre
quently involve the use of a bath of dilute, non
oxidizing acids such as sulfuric, hydrochloric,
10 acetic, formic, aqueous solutions ‘of acid sulfates,
and the like. Such baths are used for numerous
purposes, a typical example of which. is the
pickling of iron or steel articles such as wire,
sheet, and other manufactures. The composition,
concentration, temperature of operation, and
ble and much more efficient, and as such acid
' treated inhibitors are quite soluble in pickling
baths, they donot introduce suspended material
which would be deposited from the baths on
sponsive to the formation of resins under the in
?uence of alkalies and acids. A considerable por
tion of the following discussion will deal with
crotonaldehyde as illustrativeot similar unsatu 10
rated- aldehydes.
It has long been known that aldehydes. by
reason of the peculiar activity of their terminal
other factors vary with di?erent baths, but in
every instance the primary function of a bath is group, are readily converted into condensation ,
the removal of undesirable incrustations. As . products. Pure aldehydes are quite stable, but it
soon as the base metal becomes exposed, it is, in a small amount of a catalyst such as an acid, a
the absence of an inhibitor, attacked by the bath base, or a salt be added, the aldehydes' usually
with consequent damage to the article and with polymerize readily, and, in some instances, with
almost explosive violence. Some of the aldehyde
an unnecessary consumption of acid.
The application of my invention to acid pickling condensation products are well characterized or
and acid metal cleaning operations involves no - ganic compounds, but usually compounds oi’ high
changes in the customary baths and processes, molecular weight and inde?nite composition re 25
except for the addition, of a small amount of one sult, particularly with alkaline catalysts. These
of the inhibitor compositions of this application. latter complex products are di?lcult to charac
terize other than by the term "aldehyde-resinsf’.
It will, of course, be apparent that my novel in
hibitors may be used in numerous other relations _ When crotonaldehyde, for instance, is inti
as have the inhibitors already known to theart. mately mixed with an aqueous solution of sodium 30
hydroxide, a crotonaldehyde resin forms. The
I have found- that the reaction products of un
saturated aldehydes with ammonium sul?des are alkali concentration should be in the neighbor.
hood of one per cent. Larger amounts of alkali
very e?icient inhibitors. Some of my novel prod
ucts are rather di?iculty soluble, but they can be. have little additional eii’ect and are unnecessary,
dissolved in pickling baths in the required amount. and, while somewhat smaller amounts may ‘be
If treated with 'a' concentrated, non-oxidizing used, there is a lower limit, oi.’ about one-tenth
'mineral acid, these-products become readily solu
to the processes of my invention, led to the pro
duction of an inhibitor of exceedingly low em
ciency. crotonaldehyde, which appears to be the
best starting material for the manufacture of my
inhibitor, is unsaturated, and it is particularly re
pickled articles.
This characteristic is particu
larly advantageous when articles are treated
which are subsequently to be subjected to ‘proc
esses, such as enameling or galvanizing, wherein
a deposit or stain would be objectionable.
My novel inhibitor compositions, moreover, are
per cent, below which resin formation does not
occur or is exceedingly slow.
The condensation
of crotonaldehyde proceeds very rapidly ‘in the
presence of’ sodium hydroxide, and is highly exo 40
thermic. Ii’ allowed to proceed without control,
the reaction produces a temperature above 100°
C. and hard resins are formed which appear to be
partially decomposed by the heatof formation.
It is assumed that the alkali salt of hypothetical 45
hydrated aldehyde is formed
completely compatible with the foaming agents
ordinarily employed, and, in addition to their in
hibiting action, they display a notable foam-pro
which breaks down to a form
ducing ei?ciency themselves.
While any aldehyde may be employed, the un
saturated aldehydes are the most reactive and
lead to the production of the most suitable resins
55 for my purposes. The saturated aldehyde, 10!‘
more reactive than the original aldehyde.
Various salts catalyze this type of aldehyde con
densation or resin formation, particularly if the
quite diiferent in properties and character from
salt is one that reacts acidic or alkaline in aqueous
the above mentioned resins in which the sulfur
and nitrogen are introduced one after the other.
It will be readily understood that while the
above discussion refers particularly to croton
aldehyde, I do not intend to be limited thereto,
and I may use any aldehyde, though preferably
those having more than one carbon atom. The
best results, however, are obtainable with unsat
solution. In such‘ cases similar products are ob
tained as if the pure acid or alkali themselves were
used. Sodium acetate and sodium carbonate, for
instance, are salts which are capable of catalyzing
the condensations in question.
The resins formed from crotonaldehyde when
ammonia, or ammonium hydroxide are employed
10 as the alkaline catalyst, are quite di?erent from
those resulting from crotonaldehyde and sodium
hydroxide. With ammonia, or ammonium hy
droxide, it appears that at least a part of the
crotonaldehyde reacts with the ammonia to form
15 crotonaldehyde-ammonia, which, by reason of the
presence of the ammonia as an alkaline catalyst.
may then condense with itself and/or with more
The crotonaldehyde-ammonia
.or. crotonaldehyde-ammonium hydroxide resins
20 contain nitrogen, and are different from the so
dium hydroxide resins in acid solubility, odor and
When acid or alkaline sul?des are employed as
urated aldehydes. While, more speci?cally, I 10
have foundgcrotonaldehyde the most satisfactory
starting material, it will of course be understood
that acetaldehyde and aldol are fully equivalent
because in alkaline solution they are readily con
verted to crotonaldehyde.
While I prefer to use ammonium sul?de itself,
any ammonium sul?de may be employed. I may,
for instance, use such alkyl or aryl ammonium
sul?des as ethylammonium sul?de, di-ethylammonium sul?de, tri-ethylammonium sul?de, 20
ethanolammonium sul?de, di-ethanolammonium
sul?de, and tri-ethanolammonium sul?de. I may
also use such quaternary nitrogen sul?des as
a catalyst, condensation products still different in
character are obtained. The sul?des act not only
to catalyze the condensation but also to introduce
sulfur into the resin. The Sebrell Patent No.
pyridinium sul?de, piperidinium sul?de, and
sulfur, aldehyde with aldehyde, and reaction
products of the foregoing with each other, with
action products of these aldehyde-ammonium
quinolinium sul?de. It will be understood from 25
the foregoing that the term “ammonium sul?de"
is used herein in its generic sense excepting in
1,805,052 of May 12, 1931 suggests as inhibitors ‘ certain speci?c instances where reference is made
to ammonium sul?de itself.
the reaction products of aldehydes, such as for
The aldehyde-ammonium sul?de resins are,
maldehyde and aldol, with sul?des, such as hy
drogen sul?de, sodium sul?de, and the like. The preferably'dispersed or dissolved in some man
her and used in such dispersed form. They may
resins of this patent, of course, contain sulfur.
The Vignos Patent No. 1,843,653 of February 2, be dissolved in a solvent such as acetone, alco
1932, similarly, discusses inhibitors formed by the hol, ethylene glycol, and the like, or they may
reaction of aldehydes such as formaldehyde, be dispersed with such known dispersing agents 35
crotonaldehyde, and benzaldehyde with sul?des. as sul?te cellulose waste, saponin, or gum arabic.
In order to disperse the aldehyde-ammonium
Vignos, moreover, shows ammonia derivatives of
the trioladehydes as inhibitors in metal pickling sul?de resins, it is usually preferred to treat them
baths. He states that the heterocyclic compound with a concentrated non-oxidizing mineral acid.
thialdine which is formed by reacting aldehyde The resins are dissolved in such acids with a 140
ammonia with hydrogensul?de can be used as an greater evolution of heat than would be expected
for mere solution, and I believe that at least a
portion of the resin reacts with the acid. I shall,
The inhibitors of this application are essen
accordingly, designate. the resulting aldehyde
tially aldehyde resins which are formed by re
acting an unsaturated aldehyde, such as croton
ammonium sul?de resins as concentrated non
aldehyde, with an ammonium sul?de, such as oxitgizing mineral acid dispersion-reaction prod
ammonium sul?de.
When an unsaturated aldehyde-ammonium
The ammonium sul?des act not only as alka
sul?de resin is treated with concentrated sul
line catalysts for the condensation of unsatu
rated aldehydes, but, in addition, both the anion furic acid, it seems likely that the reaction re
and cation of the ammonium sul?des enter into sults in a true sulfation product containing the
the resin produced. The unsaturated aldehyde
R—O—SO3H group, but it may be that a part
ammonium sul?de resins are believed to be mix
or all of the product is a sulfonation product. I
tures .of complex organic compounds of high shall, accordingly, use the term sulfation in a
molecular weight. It seems likely that the resins generic sense, as is customary in the art, to in 55
contain reaction products of aldehyde with am
clude true sulfation and/or sulfonation.
monia, or ammonium derivative, aldehyde with
Similarly, the hydrochloric acid dispersion-re
60 more aldehyde, and/or with more sul?de or am
monia, or ammonium derivatives. 'Ihe exact
chemical constitution of these unsaturated alde
hyde-ammonium sul?de resins is not known, but
it has been determined that they contain nitro
65 gen and sulfur. It seems probable that both the
ammonia, or ammonium derivatives, and the sul
fur enter into the combinations, and this hypoth
esis is strengthened by the fact that equimolec
sul?de reaction products are of uncertain com
position, but the evidence available strongly in
dicates that they are at least in part a reaction
product with hydrochloric acid.
As will be noted in more detail hereinafter,
it is sometimes advantageous to treat non-ox
idizing mineral acid dispersion-reaction products 65
with an alkali to precipitate the resin.
In order that my invention may be more fully
ular proportions of reactants lead to the best
By employing an ammonium sul?de as a cata
understood, the following illustrative examples
lyst for the condensation of aldehydes, both
An aldehyde-ammonium sul?de resin was pre
pared by reacting molecular proportions of cro
tonaldehyde and ammonium sul?de. The croton
aldehvde was added slowly, and with vigorous stir 75
the anion and cation, then, are introduced into
the resin. The products produced by this simul
taneous introduction of sulfur and nitrogen are
are given:
Example I
av‘.- uuml U01 2 KUWG.
ring, to a twelve and two-tenths per cent solu
tion of ammonium sul?de. A considerable
which is completely soluble in dilute acids or in
amount of the water constituting the ammonium
When 0.025% by weightof this liquid product
sul?de solution was present, at ?rst, in the form of
ice so as to maintain relatively low reaction tem
was added to a sulfuric acid pickling bath (5%
H2804), it reduced acid corrosion 99.2%. Since
the liquid was made with 20% of the resin, the
0.025% of this product corresponds to the use of
peratures. A white, creamy precipitate was ob
.tained which, on drying in the air, became a white
0.005% of the resin of‘Example I. It is, then,
powder which melts at about 60° C. .
This product, which constitutes an inhibitor of
‘my invention, was difficulty soluble, but it was
~ found to be a moderately good inhibitor. About
0.005% of vthe material was dissolved in a hot
apparent that the e?iciency was raised from 92%
to 99.2% by the sulfation.
In similar studies of the eil‘iciency of the
inhibitors of Example II, it was found that 0.125%
of the sulfated inhibitor reduced acid attack
ously stirring it in the bath for a considerable . about 96.2%, and 0.00625% reduced the acid at
sulfuric acid pickling bath (5% H2804) by vigor
time. The attack of the acid on steel was reduced
tack 90.0%.
about 92%. If a higher inhibiting ei?ciency is
desired, a larger quantity of the inhibitor may be
The speci?c conditions prevailing in the sul
fation-dissolving of the unsaturated aldehyde
dissolved in the bath.
The speci?c nature of the product is greatl
in?uenced by the conditions of the reactions. The
ammonium sul?de reaction product have a con
siderable e?ect on the nature of theproduct. The
temperature of the reaction is preferably above
rate of addition of crotonaldehyde to the am- . the melting point of the resin, but not substan
monium sul?de must be adjusted‘according to the I tially above about 90° C. At’1l0" C., for instance,
rate of stirring. If the crotonaldehyde is added
too rapidly or with inadequate stirring, an in
there is considerable evolution of sulfur dioxide,
which, if excessive, may indicate an undesirable
ferior gummy, or lumpy,‘grey resin is formed.
oxidation of the resin.
This inferior product probably results by reason
‘of the inadequate dispersion of the aldehyde,
with a consequent reaction between the initial
The concentration of the acid may be widely
varied, but it must not be so dilute that it will
not react properly with resin. If the acid is very
white precipitate and aldehyde.
The temperature of the-reaction of‘ aldehyde
with ammonium sul?de must also be carefully
:30 ..
controlled if a product of the most desirable at
tributes is to be obtained.- While the product
may be made by reacting crotonaldehyde and
:35 ammonium sul?de in the gas phase, such a pro
~cedure is quite expensive, and, moreover, the
product is none too satisfactory. The reaction
could also be conducted at a boiling temperature,
but the product again is none too satisfactory.
It is preferred to hold the temperature of reac
tion below about 20° C. The cooling, obviously,
may be accomplished by any desired external or
internal cooling means.
The ratio of aldehyde to ammonium sul?de may
45 be widely varied,‘ but the most satisfactory resins
are formed when the reactants are used in sub
stantially equimolecular proportions. It will be
apparent, also, that while the ammonium sul?de
preferably corresponds to the formula (NHOzS,
50 ammonium polysulfldes of di?erent ratios of sul
fur to ammonia may be used.
The inhibitor of Example I can be dispersed
in various ways, if desired. and it may, for in
stance,,be dissolved in suitable solvents, such as
55 alcohol or acetone. It is advantageously solu
bilized by dissolving and reacting it with a non
oxidlzingmineral acid. As an example of the
procedure followed in preparing a sulfuric acid
dispersion-reaction product of an unsaturated
aldehyde-ammonium sul?de reaction product, the
following is given.
strong, for instance, greatly above 100%, there
is an excessive evolution of sulfur dioxide and 30
the product may be none too satisfactory.
The proportions of acid to resin are not criti
cal, and it is usually preferable to use a rather
large excess of acid. Obviously, enough acid must
be used to accomplish the desired reaction.
ample 111
An equal weight of the product of Example I
was stirredv into 95%. sulfuric acid. The tem
perature increased to about 100° C. by reason of z 40
the exothermic nature of the reaction. A dark
tar-like material was formed, which, after aging
at 100° C. for several hours, was quite soluble in
water or dilute acids. This material either with
or without the aging treatment, constitutes a 45
very satisfactory inhibitor.
To produce a dry,
solid aldehyde-ammonium sul?de resin, the prod~_ _ ,
not of this example was treated with solid sodium '
sulfate and lime. The solid mass so obtained
was reduced to a powder by grinding. It is 50
noted that the lime used served to neutralize
excess acid, and it may be replaced by other al
kaline solids such as sodium hydroxide.
Example IV
In order to prepare'a dry inhibitor, the prod
uct of Example II was treated with an excess
of gaseous ammonia. A precipitate was ob
tained which, after drying and grinding, was a
tan colored powder. This product’ differs from. 60
the crotonaldehyde resin of Example I in ap
pearance and character. It is ‘more soluble in
Example II
About twenty per cent by weight of the cro
water or dilute acids, and it is much more ei?
tonaldehyde-ammonium sul?de resin of Example
0.0125% by weight of this powder was added to
cient as an inhibitor than the original croton
When 65
I was added to an eighty per cent sulfuric acid
solution. The reaction was conducted at a tem
a ?ve per cent sulfuric acid solution, the acid
attack on a steel sheet was reduced about 98%.
perature of about 90f‘ C. at which temperature
Under similar conditions, 0.025% of the product
of this example reduced the acid corrosion about 70
70 'the resin, of course, is molten. After a time, the
reaction mixture was allowed to cool. The re
sulting unsaturated aldehyde~ammonium sul?de
resin, which is, of course, a dispersion-reaction
mixture, constitutes one of the preferred products
.75 _of my invention,‘ It is a black, viscous liquid
It seems probable that the product of this ex
ample is at least in part van ammonium salt of
the sulfation product of Example II. ' Such prod
ucts, obviously, are included under thegeneric 75
expression “unsaturated aldehyde-ammonium
sul?de resins.”
Instead of using gaseous ammonia to form a
dry inhibitor, I may use salt forming alkalies
such as sodium hydroxide, sodium carbonate,
ammonium hydroxide, etc. It is noted that when
tors of my invention may be sold in the liquid
or dry form as above discussed. As has already
been noted, my inhibitors have considerable efll
cacy as foaming agents, but if a greater foaming
a strong alkali such as sodium hydroxide is
used, a considerable amount of the dry product
is probably the original resin. Presumably, the
10 strong alkali at least partially decomposes the
ability is desired, they may be sold admixed with
suitable foaming agents, such as sul?te cellulose
waste, saponin, soap bark, and gum arabic, with
which they are entirely compatible. The inhibi
tors, and admixtures thereof, can be sold, also, in
solution in the acid, or acids, with which they are
be used.
sulfation product present with a consequent, to While
I have set forth a number of specific
regeneration of the crotonaldehyde-ammonium processes and speci?c compositions above, it will
sul?de reaction product. Accordingly, I prefer to
use weak alkalies, and, more speci?cally, I prefer
15 to use ammonia in the formation of alkaline salts
of the sulfation products.
Example V
be understood that I do not intend to be limited
thereby. While I have also advanced certain
putative hypotheses regarding the chemical com
position of the materials discussed and have ap—
plied descriptive designations according to such
A product similar to the one produced in
Example II was made by reacting about ten per
cent by weight of the crotonaldehyde-ammonium
sul?de resin in Example I with about ninety per
cent of 23° Bé. hydrochloric acid solution. The
reaction was conducted at a temperature of
about 70° C. at which temperature the resin, of
course, is molten.
The product obtained was a
liquid very much like the product of Example '11,
except that it is lighter in color. When 0.05%
of the product of this example was added to a
30 pickling bath, the acid attack was reduced 99.2%.
Example VI
A dry inhibitor was derived from the hydro
chloric acid dispersion-reaction product of Ex
ample V by evaporation. A dark colored, soluble
85 solid was obtained which was powdered. Acid
attack was reduced, by the use of 0.006% of this
hypotheses, I do not intend to be restricted there
by. I have fully described my invention and 20
have given numerous examples of its application,
and the terminology of the claims is to be inter
preted in the light of'the speci?cation and re
stricted only by the prior art.
I claim:
. 1. An inhibitor composition comprising a cro
tonaldehyde-ammonium sul?de resin.
2. An inhibitor composition comprising a con
centrated non-oxidizing mineral acid dispersion
reaction product of a crotonaldehyde-ammonium
sul?de resin.
3. An inhibitor composition comprising a con
centrated sulfuric acid dispersion-reaction prod
uct of a crotonaldehyde-ammonium sul?de resin.
4. A composition of matter comprising a prod
uct produced by reacting substantially equimolec
ular proportions of crotonaldehyde and ammo
product, 99.0%. The product of this example
may advantageously be sold admixed with sodium
nium sulfide.
sulfate or other soluble solids.
tially equimolecular proportions of crotonalde
Example VII
An unsaturated aldehyde-ammonium sul?de
resin similar to that of Example I, but employing
a different quaternary‘ nitrogen sulfide was pre
45 pared by reacting equimolecular proportions of
crotonaldehyde and ethanolammonium sul?de.
A viscous, greenish liquid product was obtained.
This product was poured into water and a yellow,
liquid resin precipitated. The resin was found
50 to be quite soluble in dilute acids. Acid attack
was reduced, by the use of 0.0125% of the prod
uct of this example, 98.25%. If desired, the
product of this example may be treated with
mineral acids, etc., as in the foregoing examples,
55 but it is readily soluble and does not require fur
5. A composition of matter comprising a prod
uct produced by reacting, with agitation, substan
hyde and ammonium sul?de at a. temperature
not substantially higher than 20° C. and then
treating the product with a concentrated non
oxidizing mineral acid.
6. A composition of matter comprising a prod
uct produced by reacting, with agitation, sub
stantially equimolecular proportions of crotonal
dehyde and ammonium sul?de at a temperature
not substantially higher than 20° C. and then 50
sulfating with concentrated sulfuric acid at a
temperature not substantially higher than 90° C.
'7. In a process of cleaning and pickling metals,
the step comprising subjecting the metal to the
action of a non-oxidizing acid which contains a 55
product produced by reacting substantially equi
molecular proportions of crotonaldehyde and am
ther treatment.
While crotonaldehyde is shown in the above monium sul?de.
8. In a process of cleaning and pickling metals,
examples, other unsaturated aldehydes, such as
ethyl hexenal, may be used. As has already been the step comprising subjecting the metal to the
action of a non-oxidizing acid which contains a
60 noted, acetaldehyde and aldol are fully equiva
lent to crotonaldehyde because they are readily product produced by reacting, with agitation, sub
stantially equimolecular proportions of crotonal
converted thereto in alkaline solutions. It will dehyde and ammonium sul?de at a temperature
be readily understood that mixtures, particularly not substantially higher than 20° C., and then 65
commercial mixtures, of aldehydes may be used.
It will be readily understood that the amounts treating the product with a concentrated non
mineral acid.
of my inhibitors to housed in a given bath may oxidizlng
9. In a process of cleaning and pickling metals,
be widely varied according to the nature of the the step comprising subjecting the metal to the
bath, the inhibiting e?‘iciency desired for a par
ticular purpose, etc. The adjustment of quan
titles of inhibitor used can be determined for a
particular application by those skilled in the art
according to the principles given herein and ac
cording to a few typical tests.
The aldehyde-ammonium sul?de resin inhibi
action of a non-oxidizing acid which contains a 70
product produced by reacting, with agitation, sub
stantially equimolecular proportions of crotonal
dehyde and ammonium sulfide at a temperature
not substantially higher than 20° C., and then
sulfating with concentrated sulfuric acid at a 75
2oz. UUlVHJUbl 1 lUNo.
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temperature not substantially higher than 90° C.
10. An inhibitor composition comprising a resin
prepared by reacting crotonaldehyde with an am
monium sul?de.
11. A metal cleaning and pickling bath com
prising a non-oxidizing acid and a resin prepared
by reacting an unsaturated aldehyde with an
ammonium sul?de.
.12. A metal cleaning and pickling bath com
10 prising a non-oxidizing acid and a concentrated
non-oxidizing mineral acid dispersion-reaction
product of a resin prepared by reacting an unsat
urated aldehyde with an ammonium sul?de.
13. In a process of cleaning and pickling metals,
15 the step comprising subjecting the metal to the
action of a non-oiddizing acid which contains a
concentrated non-oxidizing mineral acid disper
sion-reaction product of a resin prepared by re
acting an unsaturated aldehyde with an ammo
nium sul?de.
15. In a process of cleaning and pickling metals
the step comprising subjecting the metals to the
action of a non-oxidizing acid which contains a
resin of the group consisting of resins prepared
by reacting an unsaturated aldehyde with an 10
ammonium sul?de, their concentrated non-oxi
dizing mineral acid dispersion-reaction products,
and salts of the dispersion-reaction products.
16. In a process of cleaning and pickling metals,
the step comprising subjecting the metal to the 15
action of a non-oxidizing acid which contains a
action of a non-oxidizing acid which contains a
resin prepared by reacting an unsaturated alde
resin prepared by reacting an unsaturated alde
hyde with an ammonium sul?de.
hyde with ammonium sul?de.
14. In a process of cleaning and pickling metals,
20 the step comprising subjecting the metal to the
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