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Патент USA US2132511

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Patented Oct. 11, 1938., f'
, We comosri'lon AND METHOD
Winfrid vHentrich,'Dusselllorf-lteisl'iolz, and'Wer-
ner Reuse, Dusseldorf-Benrath, Gemany, as
_ ‘ ‘signers to Henkel & Cie G. in. b. 11., Dusseldorf
Holthausen, Germany,
a corporation of Ger
No Drawing. Application June 12, 1935, Serial
No. 26,238.v In Germany June 23, 1934 .
:12 Claims. (o1. sir-5)
This invention relates to industrial processes
which cause the reduction may be present because
, employing nitric acid wherein nitrogenous gases ~ of the particular technical process in which the
or nitrous gasesare liberated which are harmful
to the operators of ‘such processes. It may also
be considered as relating to a method of prevent
ing the liberation 'of harmful nitrous gases from
nitric acid during use, and as relating to composi
tions containing nitric acid and a substance
prevent liberation of harmful .gases.
Nitric ‘acid is employed in very large quantities
in many commercial processea'but its use involves
considerable danger because the evolution of
nitric acid is employed or the same maybe pres
ent in the nitric acid- accidentally. In either,
event, the danger from thefformation ‘of nitrous 5
gases exists. In‘ accordance with the present in
vention \the organic compound containing the
-.-N'H2 group reacts with the reduction products
of the nitric acid and forms harmless substances,
forexample, nitrogen gas or diazo compounds, 10
the latter being formed when aromatic amines
are employed. The organic compounds of the in
harmful gases occurs when the acid is brought vention may have the -—NH: group joined directly '
into ,contact with reducing substances. These ' on ‘a carbon chain or joined on a ring compound.
In one embodiment of the invention the organic 15 *
gases do considerable ‘harm to those persons com
ing in contact with the same although the gases compound may be an aliphatic, cycloaliphatic,
aromatic or a heterocyclic primary amine. Of
may be present in a very sinall concentration, fre
quently the damage done being. observable only the aliphatic amines those which possess a
after the‘passage of several hours“. Many serious straight chain of carbon atoms are most impor
injuries and frequently cases of death are re
ported in the literature of the medical profession.
tant, such compounds being, for example, methyl :0
amine, ethyl amine, propyl amine, butyl amine,
Although the dangers involved in the use of '- awmyl amine, nonyl amine, undecyl amine, dodecyl
amine, and the like. In another embodiment
amines having a branch chain are employed as
— ideal way the qualities of-a strong acid and av for ' example, isopropyl amine, isobutyl amine, 25
nitric acid arewell known, the‘use of such acid
‘cannot be avoided, for it alone combines in an
secondary butyl amine, tertiary butyl amine, iso
amyl amine, active .amyl amine, 1.1 dimethyl-Ii
: the use of nitric acid in industrial processes a amino butane, di-ethyl carbin amine, di-n-propyl
safe operation, free of hazards heretofore Yen-l _ carbin amine, di isobutylcarbin-amine.
good oxidizing agent.
' The object or the present invention is to make“
It is not nece ary that the above mentioned 30
In- accordance with ,the present‘ invention a
7‘ method has been discovered whereby nitric acid
compositions may be produced which possess the
amines be present in a pure or substantially pure ,
form, for primary amines having a content of
secondary or tertiary amines will serve just as
valuable qualities of nitric acid in undiminished
well for practical purposes. This fact is of con- 4
strength, which products eliminate‘ completely
the danger heretofore resulting from the forma-'
siderable value, for the preparation of pure pri
tion of harmful nitrous gases. The compounds
siderable dif?culties and expense.
which‘ accomplish this bene?cial result may be
referred to collectively as organic compounds
Substances with several amino groups, as, 'e. 3.,
ethylene diamine, propylenediamine, trimethylene
mary amines on a commercial scale involves con
containing a —NH: group which may be present- ' diamine and a?-trimethyl-trimethylene diamine, 40
either in the free‘or neutralized state as herein
after more fully described.
These mixtures of substances comprising the
,present'invention may be used to ‘a considerable
can also be used with advantage.
The organic compounds of the present inven
tion may contain other atoms or radicals substi
tuted in their molecules in addition to the -NH:~
advantage in most- all commercial processes
group. Thus there may be added to nitric acid, ‘5 -
wherein the use of nitric acid is valuable and
wherein the use of such results in the formation‘
substances of the nature of taurine, amino acids,
e. g., glycocoll, alanine,‘ a-amino-n-butyric acid,
of harmful nitrous gases owing to the reduction \ a-amino-isobutyric acid, valine, leucine, isoleu
of the acid by the presence of various organic or cine, ¢-amino_ caprylic‘ acid, a-amino palmitic .
inorganic substances. . Materials of the most acid, a-amino stearic acid. Furthermore, amino 50
varied chemical composition have the reducing compounds of polycarboxylic acids may be used
with advantage as, for example, aspartic acid and
effect upon the nitric acid, for example, con
glomerated masses produced by contamination or glutamic acid, a-amino adipic acid, ‘ a-amino
pollution, and inorganic substances, for example, pimelic aeid,,and derivatives of such compounds,
metals and low metal oxides. The substances as e.-_g., asparagine and glutamine; also the amino
Derivatives of the above‘described compounds
derivatives of oxy-. and 0x6 compounds, for ex
may also be used and as well salts of such com
-As an additional embodiment of the present pounds, as, for example, the acid reacting salts
invention there may be used aromatic amines / of amides derived .irom carbonic acid and molec;
5 s‘ch, for example, as the anilines, the toluidines, ular addition compounds, as, for example, the
lidines; oumidine and mesidine. Additional double bond CO(NH2) z+NaCl+Hz0.
ample, of carbohydrates.
“suitable compounds includemixed aliphatic-aro
' Those organic substances which upon reacting
with the reduction products of the nitric acid
vmatic compounds like benzyl amine. Here also,
' as ‘is true with the other compounds hereindis . yield diazo compounds, or by evolution of nitro
»\ 10 closed, substitution products and derivatives‘are gen yield compounds containing hydroxyl groups,
are considered equivalents of the primary amines
/ also suitable as, for example, chloraniline. Fur
hereinbefore described and are included within
thermore, derivatives of polynuclear compounds
may be satisfactorily used, such, for example, as
the naphthyl amines and the derivatives .of
15 anthracene, anthroquinone and phenanthrenes.
As examples of the cycloaliphatic amino, com
the present\,invention. For example, compounds
like nitroso-diphenyl- amine are employed.
. It shouldbe understood that the organic com
pounds herelnbefore disclosed may be used singly
or in combination with one or more of such come
. pounds, cyclohexyl amine and the amino com
pounds of terpenes, camphors and resins may be _ pounds, for all of such mixtures e?ectively pre
vent the escape of nitrous gases during the use
mentioned. Heterocyclic, amines, like 2-amino
' I 20 thiophene, the p-amino pyrroles, the amino pyri
of nitric acid.
lines, the
o hydroquinolines, the amino iso
' quinolines, the amino acridines,\3-amido couma
ran, 3-amido thionaphthene can The used.
When = 1w " of the aromatic and the hetero
The quantity of the organic compound con
taining the —NH2 group to be added to the nitric
acid'depends upon the extent towhich a reduc
tion of the nitric acidor the‘ amount of nitrog
> dines, the amino plperidineagthe amino quinc
enous ‘ gases
30 compounds react with a portion of the nitric acid
stances would be liberated. Naturally if only a
small quantity of the nitrous gases would be
formed onlya small amount of the organic com
pound would be needed, whereas, if the nitrous
gases are expected to appear in larger quantities,
or if it iskdesired to be on the safe side, the or
. vcyclic compounds above described are employed
withnitric acid of ‘high concentration it will be
found that not only the nitrous gases are ren
dered harmless, but also, in some instances, said
forming nltro, compounds.
The compounds of
‘ ‘= m1 ances which bring about this result are in
cluded within the broad ?eld otthe invention.
ganic compoiinds should be added-in a quantity
.7 equivalent to the nitric acid, or in an amount in
slight excess. The organic compound may be
added to the nitric acid prior to its, application or
As a further ‘embodiment of the present inven
l , 35 tion there may be employed compounds in which
during its application.
the —NH: radical is joined to an organic acid
Although many advantages follow from the use
, Thus acid amides like formamide, acetamide. ,of liquid organic substances in conjunction with
nitric acid, solid substances may also be used, for
propionamine, n-butyramide, isobutyramide, n
.40 ydleramide-trimethylacetamide, n-capronamide, if such solid or insoluble substances are employed
methyl-n-propyl acetamide, methylisopropyl ac they may be brought into action satisfactorily by
, etamide, isobutyl acetam'ide, diethyl acetamide, being dispersed throughout the nitric acid either
. Voenanthic acid. amide, n-caprylic acid amide, ' with or without theaddition of dispersing agents.
The present invention also includes all compo
g. pelargonic acidamide, n-capric acid amide, Ian45 rlc acid 'amide, trldecyl amide. myristic acid sitions which contain in addition to the nitric
acid and organic compound other substances de
signed to impart some particular property. For
example, there may be added wetting agents
adapted-to increase penetration of. the acid into
#the ‘surfaces treated,'such agents being those
which are stable towards the‘ nitric acid, for ex
ample, the sulfoacids of alkylated aromatic com
, amide, palmitic acid amide, and stearic acid
, amide can be‘ employed. Also there are included
: _ -mdes of .polyb‘c acids, 6, g,, succinamic'acid,
‘rm:- de, the amides of‘ aromatic ‘acids like
benzoic acidamide, phenylacetic acidamide, the
_ 'ipluic acid amides, hydrocinnamic (acid amide,
cumic acid amide, salicylic acid amide, mandelic
‘acid amide, vanillic acid
de, phthalic acid
pounds, ,for example, alkylated naphthalene sul
i'oacids and alkylated tetrahydronaphthalene sul
foacids. For example, there maybe added iso
amide, amides of acids'deriving from indenes, an
thracenes, and other ?oiycyclenes. There should
‘be mentioned :‘lso the acid amides of cycloali-.
phatic acids, es '- -
' propylnaphthalene suli’oacid.
For many purposes ioriwhich the compositions
oi the present invention are adapted, it is advan
tageous to employ the same in the form of a,
= of the acids which are de
rived from temenes, camphors and natural re's
ins. As substitutes o1’ heterocyciic amideathere
. This paste may be formed with consid».
' oo'mafy be mentioned for example, the amides 'of'
vp'yrrol . carboxylic acids, furancarboxylic acids, erable success by employing merely an aqueous
solution of salts or addition products of the here
In an additional embodhnent._,of'the invention in mentioned organic amine or amide compounds.
Those substances which ?nd use primarily in
65 the
4am group
may be Jcined‘onThe
acid such compositions comprise the acid reacting
thiophenecarb'owlic acids.
"amides ma
before described
.7 the some groups as herein- >
connection‘ with‘ the\ainines'
salts and addition products oi.’ amino derivatives
of carbonic acid.
Furthermore, very satisfactory pastes can be
such compounds, it appears-su?icientto refer to“ formed by mimng the compositions with suitable '
and the organic acid amides. As, emmplesmr
r. w‘
sulfode and toluene'suli'onamide. /
In still another ement oi the'invention
amides which may be considered as derived from
nic acid ‘are employed. such compounds in
thickening agents, in particular inorganic sub
stances such as iniusorial earth-and diatomaceous
earth. ‘Furthermore, other neutral or acid'reac
tion substances, for example, salts like potassium
‘ c1
dineghydantoic acid,~/allo- ' sulfate, may be added.
'- 1-.» acid, biuret and ctine.
_ -' '
The e?ectivenms of the compounds comprising 7|
' r the present- invention appears independent or
walls are brushed down with the aid of water
the surrounding temperature, for the liberation
of nitrous gases is effectively prevented at all
temperatures normally encoimtered. The per
and then rinsed oii’.
centage of amine or amide compound employed 1
The inside or a container used in the brewery 5
industry covered with beer scale is coated with
' appears to be somewhat dependent upon the tem
J perature and also upon the particular conditions
“encountered in the cleaning or other process at
smmnle 2
a paste made from 62 parts, by weight, of 50%
nitric acid, 16 parts by weight of urea' and 22
parts by weight 01 iniusorial earth. After the
paste .has vbeen applied for half an hour, the m
Where thesubstances which cause the reduc
tion of the nitric acid are present in a very small walls are brushed of! and rinsed. By such pro
quantity or , are accidentally introduced, the cedure, the beer scale is removed without danger
organic compound need be present only in a to the operator.
Example 3
very small amount. Also a small amount of the
15 compound is sufficient to maintain stabilization
Two hundred and fifty parts by weight of 15 A
during transportation. The present invention is
particularly valuable in those industries which
taurine are introduced into 630 parts by weight
can be said to be dependent upon nitric acid as a.
ture 135 parts by weightoi diatomaceous earth
vcleansing agent _for satisfactory operation. In
of a 20% solution of nitric acid. Into this mix
are ‘added during stirring with the result that a
the food industry the present compounds are . soft plastic composition is obtained. This prep- 20
particularly valuable for'removing vdeposits from
storage tanks and other apparatus. Encrusta
tions as, for example, beer scale and milk scale,
.and deposits formed in evaporation apparatus
25 used in the sugar industry, react with nitric‘ acid
applied for dissolving the same, and as hereto
fore practiced evolved harmful nitrous gases.
According to thecpresent invention, these gases
' are made harmless by adding to the nitric acid
30 a suitable quantity of an organic substance con
aration is very well suited for the removal of beer
scale and similar deposits found in the apparatus
used in the food industry.
Example 4
Three hundred parts by weight. of glycocoll
are‘mixed with 720 parts by weight of a 35%
nitric acid solution containing 20 parts by weight
of isopropylnaphthalene sulfo-acid. This mixture
is then made into a plastic mass by incorporating 30
taining a —m group., The reason why nitric . into the same 180 parts by weight of iniusorial
acid must be used in removing beer and milk earth.
emmpze s
scale is that other cleansing agents more or less
fail to work and strong alkali acids corrode the ’
A composition is formed by mixing 12 parts by ‘35
aluminum walls of the containers.
weight of acetamide with 25 parts by weight of
If the process of the present application is ac
complished under such conditions that salts 50% nitric acid. This mixture reacts strongly
acid and is very well suited for the removal 0!
combine with the nitric acid, or addition com
‘ pounds of nitrlcacid with amido compounds of
carbonic acid are used, an additional advantage
is obtained in that the products, contrary to the
results obtained 'with free nitric acid. do not
deposits of the most varied ' character.
formation of nitrous gases is completely avoided 4 0
by the presence of the acetamide.
Example 6
cause the skin of the operator to turn yellow. ‘I
Ten parts by weight 01' 9,5133% methylamine s0
Thereby the cémposition may be very convenient- ‘ lution are mixed with 32 parts by weight of a
1y handled and under suitable conditions such
compositions do not corrode aluminum, tin and
similar metals and alloys. . With such products
the packing, transportation and. storage is
especially simple.
25% nitric acid'solution during cooling. A solu- 45
tion is obtained which is strongly acidic and suit
able for the most varied cleaning purposes. '
Example 7
In processes of the above nature the beer scale
or milk, scale deposit may be removed directly or
caused to swell to such an extent that it can with
During cooling, 20 parts by weight of benzene 50
sulfa-amide are mixed with 45 parts by weight
of a. 30% solution of nitric acid. The product ob
ease be removed by any ‘ mechanical operation. tained possessing strong acid properties ?nds
,\ The condition of the scale at the end of the - employment in processes similar to those for‘
treatment depends somewhat upon the acidity of
the product used. ‘In order to prevent a prema
ture ?owing on of the solution from the walls of
the containers being cleaned, inert thickening
agents maybe. advantageously used, thickening
'60 agents of the nature of ground diatomaceous
earth. and iniusorial earth being preferred. The
duration of the cleaning process is dependent on Y
the strength of the solution employed and the
nature of the deposit on the walls or other parts
65 of the containers or-apparatus in which the so
lution is employed.
which the product of Example 6 is suitable.
It should be understood that the present’ in
vention is not limited to the speci?c disclosure -
here‘inbeiore given, but that it extends to all
compounds coming within the general tenor of
the disclosure and the'scope of the appended?"
We claim:
1. The method of cleaning organic deposits
from apparatus used in the food industries and
the like with nitric acid and preventing the liber- “5
ation of harmful nitrogenous gases from the acid,
which comprises admixing an organic compound
Example 1 _
containing a ‘—NH= group with a nitric acid clean
I A pastels made by mixing a 16% aqueous so
ing material in an amount sumcient to react with
70 lution of urea nitrate with 40% ground diatoma
nitrogenous gases which otherwise would be. lib- 70
ceous earth and applied to the 'inner'surtace oi! ‘ erated from the acid and applying the resulting
an aluminum storage vat employed in the brew
composition to deposits to be removed from the
ery industry, said surface being covered with a apparatus. 1
heavy deposit of beer scale. After a reaction '
2. The method or cleaning organic depo?ts '
1 period of an hour at ordinary temperature, the -
from apparatus used'in the food industries and‘ 75
the like with nitric-‘acid and preventing the liber
'1. mile method-described inv'claim 1 ‘w
$1,"! 2;; the{_
ation of harmful nitrogenous gases from the acid,
which comprises admixing a primary amine insoluble innate: ‘and. is main
compound selected from the group consisting of - throughout the nitric acid composition'hy at is
of adispersingv agent.
aliphatic,’ cycle-aliphatic, aromatic and hetero
8. The method described- in claim 1 wherein
cyclic amines, and their salts, addition products
the mixture of compounds contains also a wet- - ' "
and derivatives with a nitric acid cleaning ma
ent adapted to assist the‘ penetration of
terial in an amount sumcient to react with nitrogé ting
enous gases which otherwise would be liberated
'10 from the acid and applying the resulting compo
sition to deposits to be removed from the ap
the nitric acid into thesurface treated.
9. The method described vin cl
the'mixture of compounds con
‘I1 ,1
WW1 -
w an‘ inev
-10. ‘A nitric acid comtion tor the rovai.
from apparatus used in the food industries: and of “deposits from surfaces without 11
<1 3. The method of cleaning organic deposits
15 the like with nitric acid and preventing the liber- ' harmful nitrogenous gases comp 1
ation ofvharmful nitrogenous gases from the acid,
which comprises admixing a primary amide com
pounding selected ‘from the group consisting of
‘ aliphatic, cycle-aliphatic, aromatic and hetero
20 cyclic acid amides, and their salts,‘ addition prod
nitric acid 16 J
enous gases whichothe, would he
‘from the acid.
a,“ a;
ii. The method of treating nitric acid to pre-=~_
ucts and derivatives with a nitric acid cleaning
vent the liberation of
material in an amount
when said acid is handled which comp c» ~
cient to react with
nitrogenous gases which otherwise would be lib
erated from the acid and applying the resulting
25 composition to deposits to be removed from the
, apparatus.
4. The method described in claim 1 wherein
Y' the, organic compound containing the -.
group is an amide compound of'carbonic acid.’
a II
a 11mm
amount amide.
saidto react
de being
;5. The method described in claim 3 wherein
the amide compound is a sulfonamide.
6. The method described in claim 1 wherein
the mixture of comds is applied in the form
of a paste adapted to hold the mixture in ‘con-'
tact with the surfaces 1-» v it
a 1-“. ul nitrogenous
ing' to the acid asulfurfree acid'amide, said
g added‘ in an'am?imt su?lcient to re- 1 ' ' '
act with nitrogenous gases which with
would 25’
he libel-a
from the acid.
, 12. A nitric acid composition which does
liberate harmful nitrogenous gases con A a
‘nitric acid and a sulfur free acidamide,
d V p ,
a ‘u ount' sumcient w'w_:‘i. ‘
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