Note: Descriptions are shown in the official language in which they were submitted.
ZOO~Z78
PATENT
Docket D 8405 CA
A PROCESS FOR THE PRODUCTION OF LIGHT-COLORED
a-SULFOFATTY ACID AL~YL ESTER SALTS
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for the production
of light-colored ~-sulfofatty acid alkyl ester salts by
sulfonation of fatty acid alkyl esters with sulfur trioxide
and subsequent working up.
2. Description of the Related Art
The sulfonation of fatty acid alkyl esters for the ~-
production of ~-sulfofatty acid alkyl ester salts (herein-
after referred to as "ester sulfonates") has long been
known. On an industrial scale, the starting materials used
are fats and/or oils of vegetable or animal origin from
which the fatty acid alkyl esters are obtained either by
hydrolysis and subsequent esterification with lower alkan-
ols, particularly methanol, or by transesterification of
the natural triglycerides with lower alkanols. Depending
on the origin of the natural starting material, the fatty
acid ester mixtures obtained contain esters of fatty acids i~
covering a comparatively broad chain length range of
normally from 6 to 22 carbon atoms. In known processes,
these fatty acid ester mixtures are preferably sulfonated
with gaseous sulfur trioxide. This leads to more or less
heavily discolored, acidic crude sulfonates which are
; bleached and converted into ester sulfonate pastes by
neutralization to a pH in the range from about 6 to 7. In -~
this form, they are of considerable importance as surfac~
tants for washing and cleaning purposes. ~-~
Despite optimal industrial sulfonation conditions,
batches which can only be blleached with difficulty, if at ---~
, -,: ,
Z()O()Z78
~:~.3., .~r~ lc~ M~:~ t~ For~l r~p ~ d il~fJ~ tr~ u~s ~e
t`~ eni: t y o~.~t:.2i ~ 1 in the ~r~s~ t loJt of ~sto~ at~ .
qh~ arl~ t lon 01~ d~k c~olo~d pxc)~ ts is larg~y
~:t.cl~t~tl t.o oxl~J~:.Lorl ~ruduc:t~ th~.t l~A~:~.y ~c:!d ~ter
u~d ~),yf~raxyt ~i~.y~iroxy, c.)~ 4~ ) whlr,h, or~ o on~s
~rtfl, ~r~A.lt ~ tlv~ r~CI~ J ~' tha
i~Atty ~lCS kl ~ p~ ur~.ng pro~auctLon ~nd ~t:or~g~ o~ ~hc
~f~ flr~ur ll~g p~ U~ e Alkyl ~4rf~ arid
whi~h, C3n th~! C~ hP~nd, n~4 or~l~sd clurlny ~UL~Or~t~On af
~h~ al~y~. efi~t;*r~ .h g2~eou~ ~ulfur tr~ 1d~ by ~he etrong
i t~t~ s~h~ a~ tr~.ox~
l'he f~ rm~n ~ OXC3 ~ecorld~ry ~:odu~ .UriJn~ working
~Ip Q~ tri~.~.y~3rld~.s tD th~ ~y/irf~J~n~ttQd ~ y a~1cl
h~. .ti.s i by tec33n s~:1 m~.7l~3 by pun~ ul~--
~icrl in th~ ~b~S~ f ~.~ r or t,y l~i~ti~ ,On Vid bo3~1C
we.,~ t~ ni~ r*~ h~ ,r~ littl~
f ~c~ h~ s~ ~t~)s~at~ th~ lky~ t~r~ ~. h;rJow
l~lr~ U~ e}~ O,~r l(~l~sing e~Cfre~.t Or tl~ f3ul~ur t~;.L;~xi~e c~n
c~ y 1~ c~uc~~d ~y ~n~rl3u~:eo.n~L~ pl~3~.~n~J n~ ~h~
2C1~lul fi3r ~r~.ox:Ld~ hc,we~r~r, un~l~r~ut.:~n~lon l~d8 ~.o
r~ y~ or~pl~x~ Ag~n~ wh~c~h h~v~ ?~ p~po~ed
U/,t;~! t Por f~x~mE~ , d 1~x~n~ ( M . 6ut~ar ~ ~ ~, J ~ At~ .
~:nR~n. sc~ ~ Q ~ B), 53~3 540,, 3.1.kyl pho~ph~t~ ~A.~.
T~r~k ~ ~, 0, Inàl. ~ng. Ch~m. Protl. R~ V~relop. 2
2~ 317 ~t~ t~yl ~ .tt~ S. ~ ya~
~hem. ~ , Jap~n D~7 ~lg74], ~47~-~?4751. ~o~r~v~r, the
pr~ m~n~ n~ ar~ nd~d ~-~r th~ dL~2,dtt2~ t~a~,
or~ t;h~3 ~n~ h~nd, they lead t~ .~.ndu~r~lly ln~dequate
c4~l~fre~ t~ r~d/s~r ~n t~ h~r l~ar~ ~r~ t~nd~
3Q ~onsider~ble ~r~p~rAt~ve ~ lcul~:iea, ~o th~ hey are
url~uit~le rvr indu~tr~Al ~pplicat~on.
~rh~. pro~len~ addr~oR;~ ~y the pr~h~ ~nv~n~lorl Wfllj~, on
the ~)ne h~d, tc) pro~ride ~ mprov~d pro~e~ ~or t~e
produ~ioP~ of ll.qht-colored a~ lfo~tty acid al}~l R~tsr
~alt~ by ~ullf~r~at~on og ~atty as~id ~lkyl e~st~r~ s~lth ~
~uli~os~ti~cJ ag~!r!~ ~nd 9Ub~3~3qlJ21~t Wosklr~ p. PIOYO par-
t~ y~ ~ha p~ol~len~ add~ ed by the is~n~ W~B t~
~;, , ,
~;'"'1'~ ' ~ .
~'`' ' ~ ,, ' ~ ' ,
2(~0Q278
reduce the oxidizing effect of sulfur trioxide where it is
used as the sulfonating agent without the conversion levels
of the sulfonation reaction being reduced and without other
preparative difficulties arising.
S DES~RIPTION OF ~HE INVEN~IQ~
It has now been found that the addition of small
quantities of certain fatty acid amldes to the fatty acid
alkyl esters has a positive effect on their oxidation
stability, so that only small quantities of color-active
oxo compounds are formed and ester sulfonates of uniformly
high color quality are obtained in the sulfonation with
sulfur trioxide.
The present invention relates to a an improvement in
a process for the production of light-colored ~-sulfofatty
acid alkyl ester salts wherein a fatty acid alkyl ester is
sulfonated with gaseous sulfur trioxide to produce a
sulfonated reaction product and wherein the sulfonated
reaction product is subsequently aged, bleached, and
neutralized to form an ~-sulfofatty acid alkyl ester salt,
wherein the improvement comprises sulfonating said fatty
acid alkyl ester in the presence of from 0.25 to 1.5 mol-
%, based on fatty acid alkyl ester, of at least one fatty
acid amide corresponding to the following formula
~ . . . . .
.,:.-.:
-, ...
,, - ,~,
,, " ;- .,: . . . :, :
200~278
O R2
R1 _ 1l - N / (I)
R~
in which R1 is a linear C521 alkyl radical, R2 and R3
independently of one another represent a hydrogen atom, a
linear or branched C1h alkyl radical or R2 and R3 together
form a tetra- or pentamethylene chain of a heterocyclic
ring system, in which a methylene group may optionally be
replaced by an oxygen atom, a sulfur atom or an NH group.
In one preferred embodiment of the invention, the
fatty acid alkyl esters are sulfonated in the presence of
0.75 to 1.0 mol-% fatty acid amide.
The fatty acid amides corresponding to formula I are
known substances which may be prepared by standard methods
of organic synthesis. Examples of suitable compounds are
caproic acid N,N-dimethylamide, caprylic acid n-butylamide,
capric acid N,N-diethylamide, lauric acid N,N-dimethyl-
amide, lauric acid morpholide, myristic acid i-propylamide,
myristic acid N,N--dimethylamide, myristic acid pyrrolidide,
palmitic acid amide, palmitic acid i-butylamide, palmitic
acid N,N-dimethylamide, stearic acid amide, stearic acid
methylamide, stearic acid N,N-dimethylamide, stearic acid
n-propylamide, stearic acid N,N-di-n-propylamide, stearic
acid i-propylamide, stearic acid n-butylamide, stearic acid
N,N-di-n-butylamide, stearic acid n-pentylamide, stearic
acid N,N-di-n-hexylamide, stearic acid i-butylamide,
stearic acid N,N-di-i-butylamide, stearic acid pyrrolidide,
stearic acid piperidide, stearic acid morpholide, behenic
acid amide and behenic acid N,N-dimethylamide.
The fatty acid amides corresponding to formula I may
be used individually or in the form of mixtures of several
individual compounds. In one preferred embodiment of the
invention, the fatty acid amides of formula I added to the
fatty acid alkyl esters are those in which the substituents
R1 contain 15 to 17 carbon atoms, the substituents R2 and R3
2000278
of these fatty acid amides again preferably cons~sting of
linear alkyl radicals.
Sulfonation by the process accordinq to the invention
may be applied to esters of saturated fatty acidsi with
lower aliphat~c alcohols, particularly Cl~ alkyl esters of
saturated fatty acids containing rrom 6 to 22 and prefsr-
ably from 8 to 18 carbon atoms. The fatty acid residues of
these esters emanate from natural fats and oils and are
therefore exclusively or at least predominantly linear.
The alkyl radicals of the fatty acid esters emanate from
linear or branched, aliphatic Cl~ alcohols. Methyl esters
are preferably used as starting material for the sulfona-
tion reaction.
The fatty acid alkyl esters are obtained in known
manner from fats and oils of natural origin either by
hydrolysis and subsequent esterification of the free fatty
acids with lower alkanols or by transesterification of the
natural triglyceride mixtures with lower alkanols. Apart
from the methylene group in the ~-position, they should
contain no other sulfonatable or sulfatable groups and, in
particular, no double bonds or alcoholic hydroxyl groups.
For this reason, the starting materials - either the fats
and oils or the alkyl esters obtained therefrom -are
hydrogenated before sulfonation to iodine values below 1
and preferably below 0.5 under known conditions for the
hydrogenation of fats. According to the invention, it is
possible in principle to use individual fatty acid alkyl
esters, for example methyl stearate, as the starting
material for the -sulfonation with sulfur trioxide. On an
industrial scale, however, alkyl esters of fatty acid
mixtures are generally used.
The sulfonation reaction is carried out under the same
conditions as the relevant known processes for the ~
sulfonation of fatty acid derivatives as described, for
example, in DE-A-12 46 718 and DE-A-12 48 645. The sulfon-
ation reaction is carried out with a mixture of gaseous
sulfur trioxide and an inert gas which normally contains
21)00~8
from 2 to 8% by volume sulfur trioxide. The molar ratio of
fatty acid alkyl ester to sulfur trioxide may be in the
range from 1:1.1 to 1:1.8, but is preferably in the range
from 1:1.2 to 1:1.5. Air i5 preferably used as the inert
gas in industrial processes. The reaction temperature may
be in the range from 10 to 130'C. The sulfonation i5
preferably carried out at 60 to 90'C. The process temper-
ature may either remain constant or may be increased in
stages. Falling film and cascade reactors have proved
suitable for continuously carrying out the sulfonation
process.
Immediately after the sulfonation reaction, the
reaction mixture obtained is subjected to an after-reaction
(ageing) for 10 to 30 minutes at 70 to 90C. The reaction
product is then bleached and neutralized in the usual way.
Bleaching may be carried out in known manner with
hydrogen peroxide and/or sodium hypochlorite in aqueous
medium. The neutralization of the acidic reaction product
may be carried out both before and after bleaching.
Bleaching with hydrogen peroxide before neutralization is
described, for example, in DE-B-ll 79 931. DE-A-12 34 709
describes a combined bleaching treatment in which the
treatment of the acidic reaction product with aqueous
hydrogen peroxide is followed by neutralization of the
partly bleached sulfonation product which is then subjected
to a concluding bleaching process either again with hydro-
gen peroxide or, better still, with sodium hypochlorite.
According to DE-A-33 19 591, the crude sulfonation product
is first subjected to preliminary bleaching with sodium
hypochlorite in a neutral to mildly alkaline aqueous
medium, after which the salt paste is mildly acidified and
rebleached with hydrogen peroxide or compounds yielding
hydrogen peroxide.
The neutralization of the acidic sulfonation products
is carried out with aqueous potassium hydroxide solutions
and preferably with aqueous sodium hydroxide solutions.
The bleaching and neutralization conditions should be
~,,, ,.,.,~ , . .. .........................
. . - ., .
s,. .~
2000Z~8
5~ y~ .h~t~r, ~rl~ h ~ ps~ lo
l h ~ p ~ . 6 ~ g la l y X~U 1 Q~ u 1 ~
r~ff~ ~J~r~ J ~ lnlr~n~lon, ~ ddi-
t:lon. ~ t' ~m~ll qu~n~ikler~ o~ r,~ y .~ ald2~ ac~rr~spond~ng
~o Pax~nu;l~ urp~ln~l.y t.. nc.~rea~ t:h~ ~tabil.Lt~ the
:~utky .af.~ lkyl ~wter~ 0 oxlL~i~lnq ~r~c~: Or th-3
ru~ tr:ioxi~. In t:h~ Gul ~OI~r?ltiO7l ol~ the ~tt:y ~ld
al~yl e~ in 1;he ~re~ence ol' ~atty ~c:id amide~ co~rts-
~;p~ndin~ to ~or~,ula I, ~tion o~ cul~.r-ac:t~l/e
1~ ~ly~ Xy ~n~ ~xr~ ,t~iv~_ive~ np~ t~ b~
ly ~uppr~e~qad ~o th~t~ ul~rn~1:y ~c:icl o~t~r 81~11t8 of
~cis~ ry ~ or ~ual It~ an ~ ~h~is~
Ir~ the ollowln~ ~x~mpl~ ul~Jrl~t~n ~ ~h~ ~atty
~oi.~ al)~:yl ~qte.r An~ wor}ci~g up ~ th~ cruda ~u1rona~lon
procluct ~r~ ~axried o~ by t~ f~ w1ng~ ~t~nd~r~ thod:
~n A 1 l~t*r ~ndar~l rehctor ~quipp~d wl~h 9 hsat1ng
and ~oo.l itlg ~ck3t ~ncl ~ g~ 1 t~ p.;p~, :L mol ~a~y ~
~1~;y1 ~3t:er i~ ~nt~s~iv~1}r mlxed wit~ the p~rti~ r ~tty
~1cl ;~m1~ erm.ll1a I Qlrvi~e~gQc3 ln th~ qu~a t:lty ~nv 1 3age~
.~o and th~ x~suît1n~ s~ s~re nQ~td t~ C. Th~ ~t~y z~c1d
r.~ wa~ h~n ~ c'c~d wl~s ~ ul~r
trl~xi~ c~ OA~ O~ 1rIY t~ ~ mO1~A- r;~
.~he ~u1~ur- trioxitl~ wa~ ~xpell~d ~r~m el c~re~pond~ng
~u~.r~t.i.~ c~l~u~! by heat~ ng, ~.~ ltA~t~ ~t~l nlt:rog~n t~ a
~c~nc~ln~ra~ion o~ 5~ hy i~lun~ an~ in~r~d~ed ~r~o th~ f~tty
d ~ 3rt ~tt~!r r>~ r ~ perl~a ~ m.~ tes, 'I~h~ ~mp~r~
atur~ ~E th~ r~c~.on mlxtur~ u~ ~ept below gO~C.
A~ su~oF~a~n, the ~ e ~u1f~n~t~on pr~ ua~ WAC
t; ~ c~e~ rl ~ti~r~r~ tl~ Qr l~ n~r.~t~ at ~o~
3~ in a b~t~r ~A~z.~h ~d ~ th~n nnutrk11z~cl by s~irr1ng tnto
a ~in:l uti~.)n ot 4,1 ~ mc~1) fsodlum hy~roxlde ~n 500 ~1
uater .
~for2~ th* c~lu~ s1u~e; w~re d~rmIn~, tl~ ulfo-
at~.y acid ~' kyl ~t~r ~;~d~u~ lt w~* ~ ch~d ~or 120
minut6~a ~f~ t.h~ adæiti~s~ o~ ~ by ~rsight, b~s~d on
u~h~ng~a~t1ve ~h~tnnce, o~ ~o~1urQ h~poc~ rit{~.
.h~ color valu~ me~u~en~n~.~ w~r~ c~rri~d O~lt
~i:` `
200V278
. .....
. .~ . ..
photometrically ~y the Klett method at an anlonic surfac-
tant concentration of 5% by weight and at pH 7 using a 1 cm
round cell and a blue filter (400 to 465 nm).
In the comparison tests, the fatty acid alkyl ester
was sulfonated without the addition of fatty acid amides
corresponding to formula I.
EXAMPLES
EXAMPLES 1 and ~
The starting material used was a tallow fatty acid
methyl ester (chain length distribution in the fatty acid
residue: 50% by weight C16, 50% by weight C18: saponification
value 198; iodine value 0.2). This starting material had
been obtained from high-quality beef tallow (fancy tallow);
its fatty acid component had only been slightly damaged by
production and working up.
The tallow fatty acid methyl ester was reacted with
sulfur trioxide by the standard method described above in
the presence of 0.25 to 1.50 mol-% stearic acid amide or
stearic acid N,N-dimethylamide. The Klett color values
observed for the-resulting ~-sulfofatty acid methyl ester
sodium salts are shown in Table I in relation to the color
value of an end product obtained without the addition of a
fatty acid amide.
200(~8
Table I
Sulfonation in the presence of stearic acid amide or
stearic acid N.N-dimethylamide
_ . . . _ .
Example Mol-% Klett color
value
1 Cl7H3sCNH2 0.25 24
0.50 20
0.75 24
l.00 21
1.50 30 ~:
~,
2 C~7H3scoN(cH3)2 0.25 21
0.50 18
0.75 ll ~-
1.00 13 -: :
1.50 18 --~:
Comparison 1 no addition - 42 ~ ~.
- :-~ :
EXAMPLES 2 to 22
The starting material used was a tallow fatty acid
methyl ester (chain length distribution in the fatty acid
residue: 50% by weight C16, 50% by weight C1B; saponification :
value 198; iodine value 0.9). This starting material had
been obtained from low-quality beef tallow (A tallow); the -
fatty acid component had been damaged by production and -::
working up.
The tallow fatty acid methyl ester was reacted with
sulfur trioxide by the standard method described above in
the presence of quantities of O.S and 1.0 mol-% of the
fatty acid amides of formula I shown in Table II and worked
up to the corresponding ~-sulfofatty acid methyl ester
sodium salts. The Klett color values of the respective end
~ :
~ .. .. .
f~O()()Z78
products are shown in Table II by comparison with the color
value of an end product which had been obtained without the
addition of a fatty acid amide.
~.~ ,""" "~ ... , ,..,: ,~ : , ~. , , ., - .
q: ~. --., ~ . . .. .
: ZO 0 V ~ 7
Table II
Sulfonation in the presence of fatty acid amides corre-
spondina to formula I
R1 _ C - N /
\ R3
,
Example Rl R2 R3 Klett color value
0.5 mol-% 1.0 mol-~
,
3 C17H3s H H 93 76
4 Cl7H3s CH3 H 90 74
C17H3s nC3H7 H 90 81
6 C17H3s i-C3H7 H lO0 85
7 C17H3s nC4Hs H 105 87
8 c17H3s iC4Hs H 108 91
9 CSH1l CH3 CH3 108 82
C1lH~ CH3 CH3 110 82
11 C13H27 CH3 CH3 lO9 79
12 ClsH3~ CH3 CH3 110 75
13 Cl7H3s CH3 CH3 88 68
14 C2lH43 CH3 CH3 108 85
C17H3s nC3H7 n-C3H7 95 79
16 C17H35 i-C3H7 i-C3H7 98 78
17 C18H3s nC4Hs n C4Hs 105 87
18 C17H35 iC4Hs i-C4H9 99 79
19 C17H35 - (CH2)4 - 97
C17H35 - (CH2)5 - 103 75
21 C17H35 ~ (CH2)2 - ~ (CH2)2 86 71
no addition 163
.. . . ~
.. ..
11 :
