CA1273638A

CA1273638A - Process for the preparation of phosphate surfactants

Info

Publication number: CA1273638A
Application number: CA000490236A
Authority: CA
Inventors: Elvin R. Lukenbach; Richard R. Tenore
Original assignee: Johnson and Johnson Baby Products Co
Current assignee: Mitsubishi Materials Corp
Priority date: 1984-09-10
Filing date: 1985-09-09
Publication date: 1990-09-04
Anticipated expiration: 2007-09-04
Also published as: JPH0671546B2; AU574834B2; JPS6178429A; ZA856895B; BR8504323A; ES546800A0; GB2166443B; PH21536A; ES8606365A1; GB8522328D0; GR852165B; AU4719285A; US4617414A; GB2166443A

Abstract

PROCESS FOR THE PREPARATION OF PHOSPHATE SURFACTANTS

ABSTRACT OF THE DISCLOSURE

A process for the preparation of phosphate compounds comprising (1) reacting an inorganic phosphate salt with epihalohydrin to obtain a phosphate ester and (2) reacting the phosphate ester with a substituted amine wherein step (1) is carried out at a pH of from about 5.4 to 7Ø

Description

36~8 --1-- .
. PROCESS FOR THE PREPARATION OF PHOSPHATE SURFACTANTS
.

BACKGROUND OF THE INVENTION
. . _ The present invention relates to a process for the preparation of phosphate surfactants. More particularly, the invention relates to an improved process ~or the preparation of surfactants containing a hydroxypropylene phosphate group.
The phosphate substituted surfactants include phosphobetaines of the for~ula 1S r 1ll R+ - Y ~ O - P - B X~-. A

wherein A is selected from O~, OM and -O-Y-R~
B is selected from O~ and OM
X-is an anion Z is an integer from O to 2 with the proviso that only one of A and B can be O- and Z is of a value necessary for charge balance, R is an amine or an amidoamine reactant moiety, and Y is alkylene or substituted alkylene.

These phosphobetaine surfactants are fully described in U.S. Patent No. 4,215,064.

~.''~ '' .-,

-2-The phosphate substituted surfactants also include phssphitaines of the formula o R+ Y - O - P - H
O~

wherein R is an amine or an amidoamine reactant ~oiety and Y is alkylene or substituted alkylene. These phosphitaine co~pounds are more fully described in U.S~ Patent No. 4t261,911.

The phosphate substituted surfactants ~ay also include .pyrophosphobetaines of the for~ula O O
R+ - Y - O - P - O - P - A Xz~
A A

wherein A is selected frcm O~, OM and O-Y-R~ with the 2roviso that at least one A is O-X is an anion Z is an inte~er fro~ 0 to 3, a value necessary for charge balance, R is an amine or amidoamine moiety, and Y is alkylene or su~stituted alkylene.
These pyrophosphobetaine co~pounds are more ~ully de-scribed in U.S. Patent No. 4,382,036.

j.

~! r~'73638 The phosphate substituted surfactants described above all exhibit outstanding foaming, viscosity-building, wetting, cleansing, detergency, anti-static and emulsifying properties and are, therefore, useful in industrial applications calling for high performance surface active agents. The compounds are also highly stable species and are extremely well tolerated by human tissue, i.e., they exhibit exceptionally low ocular irritation and oral toxicity, and are, therefore, eminently suited and useful as surface active agents in personal care co~positions, such as shampoos, conditioners and the like.

In the preparation of the various phosphate substituted compounds set ~orth above, the processes generally comprise two steps: 1) reaction of an inorganic phosphate salt with epihalohydrin to yield a phosphate ester alkylating agent and 2) reaction of a substituted amine with the phosphate ester alkylating agent to ~orm the desired phosphate substituted compound.
In U.S. Patent No. 4,283,542 which describes processes for the preparation of phosphobetaines, there is a general description of the above process. In colu~n 11 of that patent, d process is described comprising the reaction of epichlorohydrin with phosphoric acid and various phosphate salts. The most important reaction para~eter is said to be the pH of the phosphate salt. It is said that the pH
~ust be strictly controlled and "The desired pH range is from 4 to 5. If the p~ drops below 4, there is significant hydrolysis of the phosphate ester. If the pH
at which the reaction is run is too high, there will be a loss of labile organic chlorine~ When the reaction is carried out in an alkaline environment of a pH 9.5 - 10.5 optionally, the resulting intermediate had surprisingly ~,~ 73~

lost its labile organic chlorine and formed a cyclic diester . . . The phosphate salt used should have the pH
of 9.5 - 10.5 before the addition of epichlorohydrin.
This will allow for maximum formation of the cyclic , 5 phosphate diester." The yields are relatively low for ~c~
this described process.

SUMMARY OF THE INVENTIO~

It is an object of this invention to provide an improved process for the preparation of phosphate surfactants~

It is another object of this invention to provide a process for the preparation of phosphate surfactants with improved yields of said phosphate surfactants.

- Other objects of-this invention will be set forth in, or _ be apparent from, the following detailed description of the invention.
The foregoing objects and other features and advantages of the present invention are achieved by a process comprising the steps of reacting (1) an inorganic phosphate salt with epihalohydrin and (2) reacting the resulting phosphate ester alkylating agent with a substituted amine to form ~- the desired phosphate substituted compound wherein the first reaction is carried out within a specific pH range.
..
DETAILED DESCRIPTION OF THE INVENTION
The foregoing objects are obtained in a process comprising the steps of 73~

(1) reacting an inorganic phosphate salt with epichlorohydrin to obtain a phosphate ester alkylating agent; and r (2~ reacting said phosphate ester alkylating agent -5 with a substituted amine to obtain the desired phosphate substituted compound wherein step (1) of the process is carried out at a pH of from about 5.4 to 7Ø

- It has been found, notwithstanding the disclosures in the prior art, that if the pH is lower than about 5.4, the yield of the desired ester will be low, whereas if the pH
is greater than about 7.0, the phosphate ester yield will be higher, but ~he amount of released chloride will also be greater resulting in additional process separation or higher contamination of the desired alkylating agent with inactive by-products th~reby resulting in a lower ~inal yield and there~ore a more costly process.

The inorganic phosphate salts which are useful in the present lnvention are appropriate mixture.s of the following which are made to achieve the desired pH range, or acidic reagents may be ~adju.sted to the desired pH level with Na~H. However, alkaline reagents may not be adju.sted to the appropriate pH with external acids, for example, Na3PO4 ~ust be adjusted to the appropriate pH with H3~O4, not with another acid such as HCl or H2S~4.
~f the desired end-product is a phosphobetaine compound, the suitable phosphate compounds are: H3PO4, NaH2PO4, ~a2HPO4, Na3PO4 and related compounds.

If the desired end-product is a pyrophosphobetaine compound, the suitable phosphate compounds are: ~4P2O7, JBP-237 Na2H2P2o7, Na4P207 and related compounds.

~73~

If the desired end-product is a phosphite compound, the suitable phosphate compounds are: H3PO3, Na2~P03 and 7 related compounds.

I S These inorganic phosphate salts are reacted with epihalo-hydrin of the formula ~0 1~ CH2 ~ CH - CH2 - Hal to form the phosphate ester alkylating agent. The pre-ferred epihalohydrin is epichlorohydrin of the for~ula ~0~
CH2 - CH - CH2 - Cl Once again, as stated above, it is essential in the pro-cess of the present invention that the pH be within therange of from about 5.4 to 7.0 in order to achieve the desired results of good yield and favorable economic con-ditions. It has been found that if this step of the process is carried out at the pH ranges taught in the prior art, the yields will be much lower and significant amounts of side products are formed making the yield of the desired surfactant lower and~ due to by-product conta-mination, surfactant performance may be unsatisfactory.

Epihalohydrin, preferably epichlorohydrin, is de~sirable as a linking agent since it has two reactive functions, expoxide and alkyl halide, with different reactivities such that one or the other may he selected by vir~ue of the reaction conditions~ Thus, in the present invention, inorganic phosphate reagents may be linked to the alkyl halide function by the reaction of the phosphate with the :
~7~i3~3 expoxide at an acid pH. The alkyl halide function may then be lsed in a reaction with a suitable amine to form the desi'red surfactant containing phosphate anionic groups and ammonium cationic group. If the reaction is unsuc-cessful at either stage, that is, at the phosphate-epoxide reaction or at the alkyl halide-amine reaction, th~
desired surfactant is not formed. At low pH, i.e. less than about pH 5.4, the reaction of phosphate with epoxide fails, and instead hydrolysis of the epihalohydrin to dihydroxypropyl halide predominates. If this product is reacted with the amine, the alkyl halide reacts to form a surfactant having only the ammonium cationic group, that is a dihydroxypropyl substituted cationic.

At high pH, i.e. greater than about 7, the reaction of phosphate with epihalohydrin occurs, but with cleavage of the alkyl halide to form an inorganic chloride. Thus no group reactive to amine remains, and so the amine remains unchanged.
Only in the specific pH range o~ the present invention is the phosp~ate linkage to epihalohydrin occurring in high yield with little hydrolysis of chloride. This intermedi-ate then has the optimal utility in the formation of the desired phosphate surfactant when reacted with the amine.

The phosphate ester alkylating agents formed by the reaction of the phosphate salt and epihalohydrin are of the following formuli, respectively, J~P-237 ~ ~73~i~B

Hal - Y - O - P - B

. Hal - Y - O - P - H
' I
O
O O
Il 11 ~al - Y - O - P - O - P - A
A A

The appropriate phosphate ester alkylating agent is then 2~ reacted with a substituted amine to form the desired phosphate substituted compound.

The amines which are useful are primary, secondary and tertiary amines of the following or~uli:
R3 o R2 ~3 11 1 ~ I
Rl - N and Rl C - N - (CH2)n ~ I

wherein Rl, R2, R3 and R4 are as defined below.

The resultant phosphate substituted compounds are of the general formula O

- R+ - Y - ~ P t B Xz~
A ¦ n J~P-237 ~ ~73~

g _ where-in A is sele~ted ~rom O , OM and Q~y-~
B is sel~ctefl from O~, OM and H
S X i5 an aniQn n is an integer of l or 2 Z is an integer from 0 to 3 as required for charge balance.

R is an amine or an amidoamine moiety of the formula r 131 r fi R2 R~
Rl - N _ - or Rl - C - N~(CH2)m 1 _ R4 RL~

wherein Rl is an alkyl, alkenyl, alkoxy, or hydroxyalkyl of from 5 to 22 carbon atoms, each, or aryl or alkaryl o~ up to 20 carbon ato~s, : 25 R2 is hydrogen or alkyl, hydroxyalkyl or alkenyl of up to 6 carbon atoms each or cycloalkyl of up to 6 carborl atoms, or polyoxyal~alene of up ~o 10 . carbGn atoms, and R,~, which rnay be the same or different, are selected fxcm alkyl, hydroxyalkyl, carboxyalkyl og ~p to fi carbon atoms in each alkyl moie~y, and p~lyoxyalkylene of up to l0 ca~bon atc,~s; in addition, R3 and R~ taken together with the r~! ' ~, i..,3 ~.2~3~i3~

~lQ-nitrogen to which they are attached, may re?re-sent an ~-heterocycle, e.g , a inoropholino structure, in which the Y radical is bonded to 2 ring atom of said N-heterocycle other than the nitrogen of the R moiety;

m is an integer frcm 2 to 12;

Y may be alkylene, optionally interrupted by up to 3 oxygen atoms, of up to 12 carbon atoms, which alkylene chain may optiorlally be substituted with lower alkyl, alkoxy, hydroxy or hydroxyalky', e.g., of not more than 10 carbon atoms each;

1~ M is hydrogen, an organic radical selected from alkyl or hydroxyalkyl of up to ~ carbon atoms, polyhydroxyalkyl of up to lO carbon atoms, glceryl, cycloalkyl o~ up t~ h car~on atoms, ary or arylalkyl of up to 10 car~on atoms, or a salt radical selected from al'cali metals (e.g., sodium, potassium, or a~monium and substituted ammonium radicals) and alkaline earth metals (e.g., magnesium or calcium).

The term "polyoxyalkalene" as used above in the definition of R2, R3 and R~ may be of the fonnula (R5-O-R5')m, wherein R5 and R5' are alkyl of from 1 to ~ carbon a~o~s and m is an integer from about 2 to 1~.

The follow ng examples will illus~rate in ~etail the manner in which the present invention may be practiced.
It will be understood, however, that the invention is not confine~ to the specific limitations set forth in the individual examples, but rather to the scope of the appended claims.

~.,73~

EXAMPLE I

In a suitable reactor equipped with condenser, stirring and controlled heating equipment are co~bined sodium dihydrogen phosphate (138 g as the monohydrate, 1.0 mole), disodium hydrogen phospha~e (268 9 as the heptahydrate, 1.0 mole) and water (1000 g).

After dissolution (pH 5.3) and warming to 80C., epichlorohydrin (185 g, 2 .n mole) is added and the mixture is stirred at 80C for one hour. The reduction of phosphate titer is equivalent to consumption of 1.5 mole of phosphate (75~) and inorganic chloride titer is equivalent to n . 24 mole (12~).
EXAMPLE II

In a suitablè reactor equipped for stirring and heating are combined water (300 ml) and the phosphate-epichloro-hydrin reaction product of Example I, (117 9). Thesolution is adjusted to pH 8 with 50% sodium hydroxide and lauramidopropyldimethylamine (45.4 g) is added. The mixture is heated to 85C and stirred at that temperature for 2 hours, until all organic chlorine and amine starting material are consumed. The produc~t is analyzed and found to be a phosphobetaine surfactant as described in U.S. 4,215,064.

E~CAMPLE I I I
In a suitable reactor are co~bined tetrasodium pyrophos-phate (159.6 9, 0.6 mole), sodium acid pyrophosphate (266.4 9, 1.2 moles) and water (1400 ml)~ The mixture (pH
- 5.7) is heated to 75 and epichlorohydrin (16~.5 9, 1.8 moles) is added to the stirred solution. After 1-1/2 hours, the reaction is complete, with 68~ reduction of J~P-237 ~ ~73fi~3B

inorganic pyrophosphate and 7% release of inorganic chloride, EXAMPLE IV
S
In a suitable reacto~ are co~bined the epichlorohydrin-pyrophosphate reaction product of Example III (400 9), lauramidopropyldimethylamine (71 9) and 50% sodium hydroxide (50 ml). The mixture i5 stirred at R5C for two hours. The product is a pyrophosphobetaine surfactant as described in U.S. 4,382,036.

EX~MPLE V

In a suitable reactor are co~bined phosphorous acid (41 9), water (409 9) and 50% NaOH (50 9) and the solution (pH ~) is warmed to 75C. Epichlorohydrin (46.25 9) is added and the mixture stirred at 75C for 1~1/2 hours.

Phosphite is reduced by 64% and chloride release is 7~, EXAMPLE VI

In a suitable reactor are combined the epichlorohydrin-phosphite reaction product of Example V (546025 9), 50~
sodium hydroxide to achieve pH 8, and lauramidopropyldi-methyla~ine (88 9).

The mixture is stirred at 80C for 2 hours. The product is a phosphite surfa~tant as described in U.S. 4,261,911.

J~P-237

3~

In order to demonstrate the pH-dependent nature of the reaction of the inorganic phosphate salt with epihalohydrin~ the following tests are carried out.

EXAMPLE VII

Solution A was prepared with so~ium dihydrogen phosphate (138 g as the monohydrate, 1 mole) ~ade to 1000 9 with distilled water. Solution B was prepared with diso~ium hydrogen phosphate (26~ 9 as the heptahydrate, 1 mole) made to 1000 9 with ~istilled water. V~rious weight ratios totaling lnO 9. (O.ln mole of phosphate) of solutions A and B were made; the pH measure~, an~ then they were reacted with epichlorohydrin (9.25 g, 0.10 mole) in a suitable reactor equipped with condenser, stirring and controlled heating apparatus at 75C for 90 minutes.
The reactions were assayed for the amount of phosphate ester formation and the amount of chloride hydrolysis.

The results are tabulated in Table I below and plotted in Figure I.

% phosphate %
Solution A Solution B ester chloride (ml) (ml) pH formation formation 10~ 0 4.3 24.7 0.5

4.g 37.0

5.3 ~2.~ 0 5 5.6 45.6 2~ 5.8 ~9.3 1.1

6.1 ~4.5 4.1 6.35 68.9 6.1 6.6 78.9 12.0 6.85 82.6 14.5 ~73~

EXAMPLE VIII

Solution C was prepared with sodium acid pyrophosphate (Na2H2 P2O7, 222 g, 1.0 mole) made to 1000 9 with distil-led water. Solution D was prepared with tetrasodium pyro-phosp~.a~.e (133 9, n .s ~ole) and sodium `acid pyrophosphate (111 g, 0.5 mole) made to 1000 9 with d;istilled water.

Various weight ratios totaling 100 g (~.10 mole of 1~ pyrophosphate) of solutions C and D were made, the p~
measured, and then reacted with epichlorohydrin (9.25 g, 0.10 mole) in a suitable reactor as described in Example VII.

The reactions were assayed for amount of pyrophosphate ester formation and amount of inorganic chloride formation and the results are tabulated in Table II below and plotted in Figure II.

~ pyrophosphate Solution C Solution D ester chloride (ml) (ml) P~ formation formation 100 0 4.19 17.8 0.4 ~0 20 5.~4 3~.2 0.4 5.80 39~6 2.2 6.34 49.4 5.2 0 100 6.81 61.6 ll.

3~ EXAMPLE IX ..

A series of solutions of phosphorous acid (8.2 g, 0.1 mole) in water were made to varying pH levels by the addition of 50% so~ium hydroxide such that the final solution weight is 100 9. Each solu~ion was reacted with epichlorohydrin (9~25 9, 0.1 mole) in a suitable reactor ~! ~73~

as described in Example VII. The reactions were assayed for amount of phosphite ester for~ation and amount of inorganic chloride formation and the results tabulated in Table III below and plotted in Figure III.

Table III

Solution composition % phosphite ester ~ chlori~e 10 H~PO3 50~ ~aOH pH formation formatlon 8.2 8.0 3.79 20.9 l.l 8.2 9.0 5.37 49.1 l.l 8.2 10.0 5.80 63~6 7.1 8.2 11.0 6.05 72.7 17.S
8.~ 12.0 6.29 83.6 34.4 8.~ 13.0 ~.56 87.7 51.3 The results in Examples VII, VIII and IX demonstrate the importance of the specific pH ranye of the process of the present invention.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a process for the preparation of phosphate compounds of the formula:
wherein A is selected from O-, OM an O-Y--R+;
B is selected from O-, OM and H;
X is an anion;
n is an integer of 1 or 2;
z is an integer from 0 to 3 as required for charge balance;
Y is alkylene or substituted alkylene;
M is hydrogen, an organic radical selected from alkyl or hydroxyalkyl of up to 6 carbon atoms, polyhydroxyalkyl of up to 10 carbon atoms, glyceryl, cycloalkyl of up to 6 carbon atoms, aryl or arylalkyl of up to 10 carbon atoms, or a salt radical;
R is an amine or an amidoamine moiety of the formula or in which:
m is an integer of from 2 to 12;
R1 is an alkyl, alkenyl, alkoxy, or hydroxy-alkyl of from 5 to 22 carbon atoms each, or aryl or alkaryl of up to 20 carbon atoms;
R2 is hydrogen or alkyl, hydroxyalkyl or alkenyl of up to 6 carbon atoms each or cycloalkyl of up to 6 carbon atoms, or polyoxyalkylene of up to 10 carbon atoms;
R3 and R4 are the same or different and are selected from alkyl, hydroxyalkyl, carboxyalkyl of up to 6 carbon atoms in each alkyl moiety, and polyoxy-alkylene of up to 10 carbon atoms; and in addition, R3 and R4 taken together with the nitrogen to which they are attached, may represent an N-heterocycle, in which the Y radical is bonded to a ring atom of said N-heterocycle other than the nitrogen of the R moiety;
comprising the steps of:
(1) reacting an inorganic phosphate salt with epihalohydrin to obtain a phosphate ester of the formula:
in which Hal is halogen and A, B and n have the aforesaid meanings; and (2) reacting the phosphate ester obtained in step (1) with a substituted amine selected from the group consisting of:
in which R1, R2, R3, R4 and m have the aforesaid meanings, wherein the improvement comprises carrying out step (1) of the process at a pH of from about 5.4 to 7Ø

2. The process of Claim 1, wherein the result-ing phosphate compound is a phosphobetaine of the formula wherein A, B, R, X, Y and z are as defined in claim 1.

3. The process of Claim 1, wherein the result-ing phosphate compound is a phosphitaine of the formula wherein R and Y are as defined in claim 1.

4. The process of Claim 1, wherein the result-ing phosphate compound is a pyrophosphobetaine of the formula wherein A, R, X, Y and z are as defined in claim 1.

5. The process of Claim 1, wherein the epi-halohydrin is epichlorohydrin.