US 3234258 A
Description (OCR text may contain errors)
Feb. 8, 1966 R. 1.. MORRIS 3,234,253
SULFATION F ALPHA OLEFINS Filed June 20, 1963 Fig.\ 0 commuous OLEFIN SULFATION mi cnvsmmzmeu MEDIUM 3 Ac CRYSTALL.
"Emu" cmsnc 0mm I Aclo I 8 MIX 6 mx nsmo STORAGE SECONDARY ALKYL SULFUFHC ACiD CRYSTALLIZATION TEMPERATURES CRYSTALLIZATION TEMPERATURE ("F.) I I I 130 I I "0 I I 200 210 220 230 240 250 260 270 280 AVERAGE OLEFIN MOLECULAR WEIGHT Robert L. Morris INVENTOR.
BYWCLUW 411mm u United States Patent 3,234,258 SULFATION 0F ALPHA OLEFINS lobert Louis Morri Cincinnati, Ohio, assignmto The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio Filed June 20, 1963, Ser. No. 289,351 6 Claims. (Cl. 260-460) This invention relates to an improved process for the ilfation of alpha olefins and, especially, for the producon of a secondary alkyl sulfate, rich in Z-carbon secondry alkyl sulfates useful for their detergent characteristics.
Sulfation can be described as the process of adding an O grouping to an organic molecule in such a way that slur is linked to carbon through an oxygen bridge.
econdary alkyl sulfuric acids are generally characterized.
y the formula I?! R(l3-oSo,Ir
to not 2-alkyl sulfuric acids have been generally unsatisnctory in terms of percentage yield and purity of the esired product. There have been many processes for ulfating alpha olefins proposed in recent years which sug est the use of various sulfating agents, including sulfuric cid in a wide variety of concentrations. Sulfuric acid a perhaps best suited to continuous sulfation processes. it earlier processes the occurrence of side reactions and reduction of interfering agents prevented the realization f a high Z-alkyl sulfuric acid yield. Some of the former rocesses which used sulfuric acid as a sulfating agent ndicated that low temperature sulfation could be a conentient way of avoiding undesirable side reactions and iy-products. However, yields of 2-alkyl sulfuric acid vere still relatively poor, even when lower temperatures vere used. It is essential in the production of 2-alkyl ull'uric acid that a high yield of this substance occur in :enjunction with a high overall yield of secondary alkyl ulfurie acid. if, after neulralizatizon, the sulfate product 5 to be used directly as a preferred active ingredient in l finished detergent product. Sulfate products having 0w overall yields of 2-allryl sulfates can be purified be- 'ore final use by extracting sulfated olefins and unlesired alkyl sulfate isomers; however, extraction is an :xpensive means for purifying secondary alkyl sulfates and s therefore usually undesirable for economic reasons.
Thus, it is an object of this invention to provide a pro- :ess for the production of 2-alkyl sulfates in high yields. Another object of this invention is to provide a process 'or the production of 2-alkyl sulfate, which process avoids :ide reactions and formation of undesired isomers and iy-products.
A further object of this invention is to provide a process for sulfating alpha olefins which produces a high yield of secondary alkyl sulfate with a high content of 2-alkyl sulfate.
These objects are realized in the process of this invenboiling, refluxing crystallization medium as hereinafter described, and at a temperature at which 2-alkyl sulfuric acid which is formed crystallizes from the medium. The" temperature is controlled by the evaporation (boiling) of the refluxing crystallization medium. The crystalline mixture is then neutralized by a strong base to a pH greater than 8. Because of this essential crystallization and neutralization, yields of secondary alkyl sulfate from to based on original alpha olefin, can be realized, with 75% to 95% of the alkyl sulfate being of the desired 2-alkyl sulfate'variety.
The principal achievement of this invention is a high yield of secondary alkyl sulfate rich inZ-alkyl sulfate; however, to achieve this result it is necessary that secondary alkyl surfuric acid be crystallized as it is formed and that the crystals be neutralized to the sulfate product. It has been discovered that by crystallization of the alkyl sulfuric acid as it is formed, undesired side reactions, principally formation of isomers other than the desired 2- carbon materials, are virtually eliminated in that the desired Z-alkyl sulfuric acid product is precipitated in a crystalline form which is resistant to further reaction in the environment of the reaction. Also, crystallizationof the product further promotes a higher degree of sulfation in that the reaction is driven toward completion by the effective removal of the product from the reaction. Furthermore, neutralization of the crystals before they are allowed to melt, reduces the tendency toward formation of undesired isomers of alkyl sulfuric acid.
FIGURE 1 of the drawing is a flow diagram of a preferred aspect of a continuous process for this invention.
FIGURE 2 is a graph showing the relationship of alpha olefin average molecular weight to the essential ranges of crystallization temperatures of the corresponding secondary alkyl sulfuric acids.
Alpha olefins which are suitable reactants for this sulfa- 12 to 18 carbon atoms are preferred for preparing secondary alkyl sulfate detergent compound preparations,
and straight chain alpha olefins are preferred for making easily-biodegradable detergent compounds. Alkyl sul- Patented Feb. 8, 1966 p ful as fabric softeners.
H 80 the other reactant, should be employed in the form of a 94.5% to 100% solution, the molar ratio of H 80 to alpha olefin being from about 1.5:1 to about 4:1. The excess sulfuric acid promotes rapid sulfation and inhibits formation of dialkyl sulfates. However, above a 4:] acid to alpha olefin ratio there is a tendency for the alkyl sulfuric acid crystals to become partially solubilized in the excess sulfuric acid as they are formed, thus permitting side reactions and isomerization and reducing the amount of desired 2-alkyl sulfate ultimately produced. It is therefore preferred that sulfuric acid and olefin be added to the reaction vessel concomitantly in the desired molar proportions so that a large excess of H 80 is not present at any time. Also, the reactants should .be brought together in the presence of the boiling crystallization medium so that the temperature of reaction-crystallization is constantly controlled. Below an overall 1.5 :1 sulfuric acid to olefin ratio, sulfation efficiency is reduced due to incomplete reaction. With increased reaction temperatures, acid to alpha olefin ratio should be reduced for crystallization to take place. At acid concentrations outside of the 94.5% to 100% range, desirable reactions do not materialize to a satisfactory degree; an incomplete reaction will take place with the more dilute acid solutions, and with more concentrated H 80 the formation of sulfonates rather than the desired sulfate product will occur. A sulfuric acid reactant within the specified range of concentration is essential for the sulfation process of this invention, particularly in its continuous aspects. Agents such as S oleum and chlorosulfonic acid cannot be used because they tend to produce sulfonates rather than sulfates.
The crystallization medium which is required for the reaction of this invention consists essentially of a low-" boiling (i.e., capable of boiling below room temperature (below about 75 F.)), nonionic, organic compound in liquid form which is substantially inert. to the reactants and which promotes and is compatible with, crystallization of secondary alkyl sulfuric-acid from the reaction mixture. The crystallization medium must be in a physical state of boiling under reflux during the reaction. Subor super-atmospheric pressure can be used to control boiling temperature. Organic compounds suitable for use as a crystallization medium include lower molecular weight hydrocarbons and halogenated hydrocarbons, both of which are especially useful principally because of their boiling characteristics and availability as pure substances. However, oragnic compounds which contain undesirable impurities or which are ionic in character (e.g., CH Cl, liquid S0 tend to decompose in the presence of the concentrated sulfuric acid used in carrying out the process of this invention, interfere with the sulfation reaction, or create impurities in the final product.
Organic compounds suitable for use as a crystallization medium include Freons (halogenated hydrocarbons, i.e., alkanes, such as methane orethane, having from 2 to 6 chlorine and/or fluorine substituents) which are nonionic in character, and C to C alkanes (e.g., propane, butane, iso-butane or mixtures of these hydrocarbons have all been found to be highly satisfactory). Examples of suitable halogenated hydrocarbons include dichlorodifiuoromethane (B.P. 21.6 F.), trichlorofiuoromethane (B.P. 74.8 F.), 1,1 difiuoroethane (B.P. -l3 F.), 1-chloro-1,1 difiuoroethane (B.P. 14 F.), sym-dichlorotetratluoroethane (B.P. 38.4 F.) and chlorodifiuoromethane (B.P. 4l.4 F.) (All boiling points are at atmospheric pressure.) When subatmospheric pressuresare used higher boiling crystallization media can be utilized, and, likewise, when superatmospheric pressures are used normally lower boiling crystallization media can be used. Higher or lower boiling organic compounds, which are chemically suitable can be used, if pressure is altered so as to make their boiling tempera- 4 ture correspond to the crystallization temperature of the 2-alkyl sulfuric acid product.
The particular organic compound or mixture of compounds to be used as a crystallization medium is determined by its boiling point and the crystallization temperature of the specific secondary alkyl sulfuric acid product which is to be formed. The crystallization medium to alpha olefin weight ratio should preferably be from about 0.5 :1 to about 4:1. Below this ratio range temperature control in the reaction is poor, while amounts of crystallization medium above this ratio range substantially reduce reactant concentration and thus slow down the reaction. However, within this range the amount of crystallization medium used is principally determined by the amount necessary to maintain adequate fluidity of the crystal-containing reaction mixture during the various steps of the sulfation process. Since the alkyl sulfuric acid crystals of the higher molecular weight alpha olefins (e.g., those of the C to C group) often tend to crystallize in larger, more heterogeneous masses than those of the lower weight olefins, more crystallization medium is usually necessary for carrying out the sulfation of the higher weight olefins than is required for the sulfation of the lower weight olefins. This greater amount of crystallization medium maintains the necessary reaction mixture fluidity and prevents entrapment of small amounts of crystallization medium in a dense crystalline mass. To avoid any tendency for degradation, the crystallization medium should not be the last component added to the reaction mixture.
The internal temperature of the sulfation reaction must be adequate and carefully controlled so as to insure precipitation of crystalline secondary alkyl sulfuric acid during the reaction. Depending upon the specific alpha olefin or alpha olefin mixture being reacted, the temperature (eg. at which reaction-crystallization is achieved) can be between about -60 F. and about F. and is controlled particularly in the immediate area of crystallization by the evaporative cooling action of the crystallization medium which is in a physical state of boiling under reflux at the crystallization temperature of the secondary alkyl sulfuric acid product. The reaction-crystallization temperature is essentially fixed at this boiling temperature and is variable only by changing or modifying the crystallization medium or by alteration of the pressure in the system. Crystallization temperature of secondary alkyl sulfuric acid in a reaction system varies with different acid to olefin ratios within the above ranges and is obtained by adjusting the crystallization medium appropriately to insure crystallization (e.g., increased acid to olefin ratio results in a lower crystallization temperature and thus a need for lowering of the boiling temperature of the crystallization medium). After crystallization has been initiated and throughout the remainder of the process, precipitation continues and the crystalline condition of precipitated secondary alkyl sulfuric acid is preserved so long as the original crystallization temperature remains substantially constant.
The temperature chosen for the sulfation reaction, in order to achieve crystallization of secondary alkyl sulfuric acid as it is formed, is dependent principally on the composition of the individual alpha olefin or alpha olefin mixture utilized for the reaction. The graph in FIGURE 2 of the drawing indicates the critical temperature range for crystallization of secondary alkyl sulfuric acid products from alpha olefins of varying average molecular weights, within which range the process of this invention is practiced. This range is shown by the shaded area on the drawing. The heavy line (A) approximately 10 below the upper edge of the range represents crystallization temperatures for secondary alkyl sulfuric acids derived from corresponding alpha olefins under preferred conditions as explained. Various processing conditions as explained below affect crystallization temperatures within the described range.
The information used to plot the graph and crystallization ranges of FIGURE 2 was derived from a series of alpha olefin sulfations according to the following method: High purity (more than 95%) alpha olefins of various molecular weights were used and other sulfation variables were maintained as follows: H 50 (94.5% to 100% solution) to olefin molar ratio ranged from about 1.521 to 4: l; and crystallization medium to olefin weight ratio ranged from about .5 :l to 4:1. Preferred crystal lization conditions, as shown by heavy line A, were as follows: H 30 to olefin molar ratio ranged from 2:1 to 2.211; crystallization medium to olefin weight ratio was 1:1; and H 50, strength was 97.0% :.3%. All sulfation runs were one hour long and the beginning of crystallization in less than thirty minutes time after initial combination of reactants was considered satisfactory crystallization. Crystallization is evidenced by formation of a creamy white slurry of crystals in liquid. For each of a representative number of olefin samples of varying molecular weight, reaction temperatures were systematically varied, and organic compounds (propane, iso-butane and neopentane) were selected or blended to adjust crystallization medium boiling point to the various reaction temperatures. For each olefin sample, the temperature for satisfactory secondary alkyl sulfuric acid crystallization was noted and plotted. A uniform range (shaded area) and preferred temperatures (line A) were derived from these data relating secondary alkyl sulfuric acid crystallization temperature to alpha olefin average molecular weight tie, for pure alpha olefins and blends of alpha olefius) and to variances in acid to olefin ratio and other processing conditions.
By utilizing temperatures within the shaded area range shown on the graph, an acid mix containing crystalline secondary alkyl sulfuric acid can be obtained, which on neutralization gives high yields of 2-alkyl sulfate. At temperatures above this range, crystallization either does not take place or is unduly slow in taking place. At temperatures below the range the reaction proceeds too slowly and the alkyl sulfuric acid product is so solid that entrapment of impurities and lack of fluidity make such low temperatures undesirable. Also, at low temperatures the reactants themselves may tend to crystallize. Thus, although crystallization of secondary alkyl sulfuric acid will occur at temperatures lower than those in the reaction-crystallization range of the graph, the difficulties described above which accompany crystallization at these lower temperatures make such low temperature crystallization undesirable.
The reaction pressure should be such as to permit boillug-refluxing of the crystallization medium in the reaction mixture at the proper reaction-crystallization temperature. Normally, atmospheric pressure is appropriate for carrying out the reaction and the crystallization medium is so chosen with respect to boiling point, that boiling-refluxing at the proper reaction-crystallization temperature is effected at atmospheric pressure. However, if an extremely low boiling crystallization medium is used, that is, one which boils at a temperature far below the reaction-crystallization temperature of the secondary alkyl sulfuric acid being produced, it is necessary to increase pressure (e.g., up to about 4 atmospheres) in the system to a level sufficient to maintain the crystallization medium (by raising its boiling point in the system) and maintain appropriate crystallization conditions, e.-g., temperature. Likewise, if a crystallization medium is used which boils at a temperature above the reaction-crystallization temperature of the alkyl sulfuric acid being produced, the pressure should be reduced until boiling conditions are achieved at the crystallization temperature of the alkyl sulfuric acid product. A preferred method of maintaining the appropriate crystallization conditions is to select a crystallization medium which boils at atmospheric pressure and at temperatures at or only slightly below the reaction-crystallization temperature of the sped cific secondary alkyl sulfuric acid product which is being produced.
The reaction time is dependent upon the nature of the individual olefin which is being reacted, the concentration and amount of sulfuric acid present and the crystallization temperature of the specific alkyl sulfuric acid produced. The time is not critical, although shorter times are preferred, and is principally determined by crystallization and reaction rate (i.e., time necessary to complete the reaction) and materal handling considerations. The range of usable reaction times is relatively broad, with the reaction usually being completed in about 5 minutes to 150 minutes. of secondary alkyl sulfuric acid crystals for periods longer than 150 minutes in the reaction mixture do not, however, result in significant reductions in the yield of 2-al-kyl sulfuric acid crystals.
The principal conditions which determine the development of a crystalline alkyl sulfuric acid mix are the reaction-crystallization temperatures described above and the critical acid to olefin ratios previously discussed. Other reaction variables which can affect formation of the crystalline mix and the product yield of the sulfation include H 50 concentration, the crystallization medium chosen, crystallization medium to olefin ratio and reactant contact time. Since a crystalline product is formed, agitation during sulfation is essential.
By proper choice of reaction conditions as set forth above, optimum yields of 2-alkyl sulfuric acid and the corresponding sulfates can be obtained. For example,
utilizing a 2:1 molar acid to olefin ratio, a 1:1 by weight alpha olefin to crystallization medium ratio and a 94.5% to sulfuric acid concentration, the remaining dominant variable is reaction temperature. Heat liberated by the snlfation reaction is sufiicient to initiate boiling of the crystallization medium. The necessary temperature is maintained by appropriate selection of the crystallization medium and/ or adjustment of the reaction pressure. The choice of a crystallization-reaction temperature within the range in FIGURE 2 is principally determined by the specific olefin which is to be sulifated. However, crystallization-reaction temperature for a particular average molecular weight olefin can be somewhat lowered by heterogeneity of the olefin lblend or impurities in the mixture. The appropriate crystallization reaction temperature is maintained until crystaltlization is complete and so long as the crystals remain unneutralized in the reaction mixture.
After crystallization of the secondary alkyl sulfuric acid is effected, the crystals must be neutralized before melting to realize the full advantages of the process of this invention. The secondary alkyl sulfuric acid crystals are reacted with at least an equivalent amount of a strong base, e.g., 10% to 50% sodium hydroxide solution (other basic substance can also be used, e.g., soda ash (sodium carbonate), potassium hydroxide, ammonia, and triethanolarnine). Sufiicient base should be used to provide the reaction mixture with a pH greater than 8. The heat of neutralization can advantageously be used to evaporate (flash off) the crystallization medium from the reaction mixture. Agitation is preferably effected during neutralization. Since neutralization is relatively rapid, significant isomerization of the melted 2-alkyl sulfuric acid crystals I does not occur. In the case of batch su-lfation, it is satisfactory to simply pour the entire acid reaction mixture into the base. However, when a batch technique is used care is preferably taken that the heat liberated due to the neutralization reaction does not quickly and unduly elevate the temperature of the reaction system. A rapid increase in temperature can cause the low boiling crystallization medium to violently flash off. It is therefore preferable that cooling be employed (e.g., by ice being present in the base or by using cooling coils around the neutralization vessel). The amount of cooling which is necessary is dependent on the individual crystallization Reaction times and presencemedium which is being used. With a higher boiling medium slight cooling is usually sufficient. With a very low boiling crystallization medium greater cooling may be necessary.
In batch sulfation and neutralization procedures neutralization is preferably carried out between F. and 125 F. depending on the temperature of the crystalline acid reaction mixture and the boiling point. of the crystallization medium which is being used (e.g., higher boiling mediums permit higher neutralization temperatures). In continuous crystallization-neutralization systems somewhat higher neutralization temperatures can be used, since the closed vessels used in a continuous process somewhat ofi'set difficulties resulting from rapid flashing oil of the crystallization medium. In such systems temperatures as high as 200 F. can be tolerated during neutralization, but preferably range between F. and 125 F. Neutralization can be carried out at temperatures higher than those mentioned; however, temperatures should not be so high as to char the product and precautionary measures should be taken to allow for the possibility of the sudden flashing of crystallization medium.
Variations in the technique by which neutralization is carried out can also be made. For instance, the secondary alkyl sulfuric acid crystals can be removed from the liquid portionof the reaction mixture, (e.g., by ti tration or ccntrifugation), the liquid being crystallization medium and excess H 50 So long as the temperature is not allowed to rise above the original crystallization temperature the crystalline condition of the product is maintained. The crystals can then be neutralized directly by an appropriate base. Such a technique eliminates any difficulty of the crystallization medium rapidly flashing off and sharply reduces the amount of inorganic sulfate impurities normally formed when excess H 80 is neutralized along with the crystalline product, although more external cooling is required to carry out such a procedure.
When crystallization is unduly slow in starting, it has been found that the yield of Z-alkyl sulfuric acid crystals will be markedly reduced due to the formation of undesirable isomers prior to initiation of crystallization. Under such circumstances it is desirable to seed the reaction mixture. preferably with pre-formed Z-alkyl sulfuric acid crystals to initiate this crystallization process. Alkyl sulfuric acid crystals of the non 2-carbon variety can be used to seed, although they will ultimately constitute a slight impurity in the 2-carbon secondary alkyl sulfuric acid product.
Seeding is carried out by adding a small amount of secondary alkyl sulfuric acid crystals (preferably 2-carbon) to the crystallization medium used in the reaction system. Preferably the amount added is at least about 1% of the total reaction system. (An amount sufiicient to initiate crystallization is all that is required, since as the crystals form the reaction is self-seeding). These crystals provide nuclei for crystallization which subsequently takes place during the sulfation reaction conducted under the conditions set forth above. When the alkyl sulfuric acid product is rapidly crystallized, as it tends to be when a seeding technique is used, the product is effectively rendered inert to the immediate environment and undesirable isomerization is prevented. In the preferred continuous sulfation procedure, description of which immediately follows, seeding is inherent in the system, in that new reactants are continuously in contact with the crystalline reaction product formed prior to the addition of the reactants.
Reference to the flow diagram of FIGURE 1 will clarify a preferred continuous procedure by which the process of this invention can be carried out according to the conditions deccribed above. Alpha olefin from storage 1 and concentrated sulfuric acid from storage 2 are reacted in a reactor 3 in the presence of crystallization medium from storage 10 or surge tank 5, with agitation provided by agitator drive 11. The reactants are cooled by the evaporation of the boiling crystallization medium and the vapors of the crystallization medium are condensed in a condenser 4 and the crystalline acid reaction mixture (sulfation being 70% or more complete) enters tubular reactor 6 where the sulfation reaction is completed during the period required for the mixture to pass through the coiled tubes within the reactor, and from which the completely reacted mix is discharged into a neutralizer 8. (The use of the tubular reactor in the system is preferred since it promotes the continuous process by avoiding the delay incurred by requiring the reaction to go to completeness in reactor 3.) A strong base such as sodium hydroxide from storage 7 is added to this mix to neutralize the alkyl sulfuric acid and excess H 50 in a neutralizer 8 and the neutralized paste is subjected to removal of crystallization medium in a stripper 9 and removed from the system.
The principal features and inventive nature of this process having thus been presented, the following examples serve to illustrate some of its applications. However, these examples should not be considered to be limiting in any sense. (Parts and percentages are by weight.)
Example I The sulfation apparatus used for this example consisted of a reaction vessel fitted with a mechanical stirrer and a reflux condenser, with two separate valved flasks in which were respectivcly contained the olefin and sulfuric acid reactants. The two reactants were added separately to the crystallization medium in the reaction vessel near the mixing blades of the stirrer at such a rate that the momentary molar ratio of acid to olefin, as noted below, was approximately the same as the overall molar ratio of acid to olefin. Sulfation temperature was governed by the temperature at which the crystallization medium boiled (thus requiring selection of a crystallization medium which boiled at the crystallization temperature of the specific alkyl sulfuric acid product which was to be formed). The heat liberated by the reaction kept the crystallization medium boiling, and condensed vapors of the crystallization medium were returned to the zone of the reaction.
grams of a mixture of 9 parts isobutane and 2 parts propane were prepared at a temperature of 4 F.,
the boiling temperature of this crystallization medium. To this boiling mixture was added 100 grams of l-tetradecene (average molecular weight 196) and 113 grams of 97.5% sulfuric acid (1:2.2 mole ratio), the two reactants being added concomitantly but separately to the medium over a 5 to 6 minute period with vigorous mechanical agitation. The reactants did not contact one another until they were actually in the medium. Also, the rate of addition of reactants was such that the actual momentary molar ratio was maintained at approximately the overall molar ratio (112.2).
The reaction mixture with the crystallization medium in a physical state of boiling was refluxed at 4 F. and agitated by the mechanical stirrer for about 60 minutes. During this time the mix gradually changed from a yellowish liquid to a creamy white slurry of crystals in liquid.
This acid mix at 4 F. was then neutralized to a pH of about 10 by pouring it into an open neutralization vessel containing 342 grams of a 50% aqueous sodium hydroxide solution in admixture with an amount of ice sutficient to dilute the hydroxide .to 20% concentration on melting. The vessel was fitted with a turbine agitator. The crystallization medium flashed off from the mixture. The presence of the ice resulted in a gradual increase in temperature from -4 F. to F. during neutralization, avoiding explosive flashing off of the crystallization medium.
The resultant paste contained a yield of 91% secondary alkyl sulfate based on the olefin used. Of the secondary alkyl sulfate product 84% was Z-tetradecyl sodium sulfate. Z-tctradecyl sodium sulfate is useful as a detergent compound especially when combined with three I times as much by weight of sodium tripolyphosphate to form a laundering composition, particularly valuable in removing soil from clothing and other fabrics.
Example II Sulfation of a C chain length alpha olefin (l-tetradecene) was carried out using apparatus and procedures the same as those used in Example I, using isobutane as a crystallization medium. A 2.22 to 1 acid (97.5% sulfuric acid). to alpha olefin mole ratio was used and the sulfation reaction was carried out at a temperature of- -2 F. Crystallization of the secondary alkyl sulfuric acid took place as the product was formed. The NaOH- neutralized crystals (pH constituted a 91% yield of secondary alkyl sulfate based on the olefin usage. 84% of the alkyl sulfate product was Z-tetradecyl sodium sulfate, a compound useful for a detergent application.
In comparison, at +14 F. using 9 parts isobutane to 2 parts propane as a crystallization medium and with the other conditions remaining the same, crystallization during sulfation did not take place. The neutralized reaction product represented an 80% yield of secondary alkyl sulfate. Only 42% of this product was 2-alkyl sulfate. This is illustrative of the effect of reaction temperature on formation of a crystalline product and also shows the marked effect which crystallization has on the amount of Z-alkyl sulfate which is formed in such a sulfation process.
Example III Sulfation of a C chain length alpha olefin (l-tetradecenc) was carried out using procedures and apparatus the same as those used in Example I, with an isobutane solvent crystallization medium, 97.5% H 80 and a temperature of +12 F. The acid to olefin mole ratio was 1.74 to 1. A crystalline acid mix product which constituted an 83% yield of secondary alkyl sulfuric acid resulted. Of this product 80% was Z-alkyl sulfuric acid. On neutralization with NaOH to pH 10 Z-tetradecyl sodium sulfate was formed. This latter product is useful as a detergent compound.
In comparison, when a 2.14:1 acid to olefin ratio was used at 11 F., but with the other conditions remaining the same, no alkyl sulfuric acid crystals resulted. The 81% alkyl sulfate yield (based on olefin reactant) contained only 44% Z-alkyl sulfate. This illustrates the desirability under some conditions (i.e., here when acid/ olefin ratio was too high to obtain crystals at the crystallization medium boiling temperature) of lowering the acid/olefin ratio in order to promote crystallization. Thus, here a reduction of acid to olefin ratio from 2.14 to 1.74 accomplished crystallization.
Example IV Sulfation of a C chain length olefin (l-tetradecene) was carried out in isobutane with a sulfuric acid (97.5% H 80 to olefin mole ratio of 2.22:1, using the same procedure as outlined in Example I. However, a seeding technique was used in which ten grams (3.5% of the total reaction system) of crystalline 2-tetradecyl sulfuric acid were added to the isobutane prior to the introduction of the reactants. Within two minutes after introduction of the reactants crystallization of the alkyl sulfuric acid A continuous olefin sulfation was carried out with the apparatus shown in FIGURE 1. The olefin used was 10 a blend of C and C technical grade straight chain alpha-olefins (average molecular weight 210) (iodine value 119.6). The reaction variables were maintained at the following mean values:
Stirred tank reactor average residence time (3),
hours 0.66 Tubular reactor average residence time (6) hours 0.09 Total reactor average residence time (3,6),
hours 0.75 Olefin rate (1), lb./hr 9.74 Acid flow rate (2) (97.3% H lb./hr. 9.02 Acid/ olefin molar ratio 1.96:1 Isobutane crystallization medium flow rate (5),
lbs/hr. about 10.0 Crystallizationmedium/olefin Wt. ratio about 1/1 Temperature in stirred tank (3), "F 1O Acid mix temperature at neutralizer inlet (8),
"F 18-20 Caustic flow rate (7) (20% NaOH), lb./hr. 33.0 Neutralizer outlet temperature, "F 145 State of sulfation mix going to neutralizer crystalline slurry Total time during which the above conditions were maintained with continuous operation,
minutes 120 Apparent reaction completeness, percent 88 The product detergent paste (pH 10) was qualitatively and quantitatively analysed for 2-alky1 sulfate content and 4 found to contain more than 80% of this material.
Other olefins, e.g., l-undeeene, l-octadecene or 4-ethyll-dodecene can be sulfated using procedures the same as those set forth in this example and the preceding zation temperature can be obtained by selecting or blending these compounds appropriately.
Although the present invention has been described and illustrated with reference to specific examples, it will be understood that modifications and variations can be made without departing from the spirit and scope of the invention set forth in the following claims.
What is claimed is: 1 1. A process for the manufacture of a sulfated olefin product which comprises the steps of:
(A) reacting with agitation from about 1.5 to about 4 moles of H 80 (94.5% to solution) and 1 mole of an alpha olefin containing from about 9 to 24 carbon atoms, in the presence of a low boiling nonionic, organic crystallization medium which is inert to the H 80 and olefin reactants, said medium being in liquid form and in an amount from about 0.5 to 4 times the weight of olefin reactant and suf-' ficient to maintain a fluid reaction product, said medium being in a physical state of boiling under reflux to control the reaction temperature, the temperature of boiling being within the shaded area on the graph of FIGURE 2, the temperature and pro- 7 portions of reactants and medium being chosen so as to effect prompt crystallization of Z-alkyl sulfuric acid as formed, 1
(B) continuing agitation under the conditions specified in (A) until crystallization and reaction are substantially complete,
(C) neutralizing the alkyl sulfuric acid crystals so formed directly from their crystalline state to a pH greater than 8 by addition of a strong base to produce a secondary alkyl sulfate product which is rich in Z-alkyl sulfate.
2. The process of claim 1 wherein a seeding amount of secondary alkyl sulfuric acid crystals is added to the solvent media prior to the beginning of the sulfation reaction, thereby promoting crystallization of Z-alkyl sulfuric acid.
3. The process of claim 1 wherein the olefin reactant is a straight chain olefin and the crystallization medium is selected from the group consisting of C -C alkanes,
' chlorinated and fiuorinated methanes and ethanes having from 2 to 6 substituents selected from the group consisting of chlorine, fluorine and mixtures thereof and mixtures of these.
4. The process of claim 2 wherein the olefin reactant ranges in chain length from about 12 to 18 carbon atoms.
5. The process of claim 4 wherein the molar ratio of H 80 to olefin is from about 2:1 to 22:1, the H 80 is about a 97% solution, the crystallization medium to olefin Weight ratio is about 1:1 and thetemperature of boiling is substantially on line A of the graph.
6. A continuous process for the manufacture of a sulfated ole-fin product comprising the steps of:
(A) continuously reacting with agitation from about 1.5 to about 4 moles of H 80 (94.5% to 100% solution) and 1 mole of a straight chain alpha olefin ranging in chain length from about 9 to 24 carbon atoms, in the presence of a continuously refluxing and recirculating low boiling, liquid, nonionic, organic crystallization medium which is inert to the H 80 and olefin reactants, said medium being in an amount of from about 0.5 to 4 times the weight of olefin reactant and sufficient to maintain a fluid reaction product, said medium being selected from the group consisting of C -C alkanes, chlorinated and fluorinated methanes having from 2 to 6 substituents selected from the group consisting of chlorine, fluorine and mixtures thereof and mixtures of these, the temperature of boiling being within the shaded areaon the graph of FIGURE 2, the'temperature and proportions of reactants and medium being chosen so as to efi'ect prompt crystallization of 2-alkyl sulfuric acid as formed,
-- (B) continuously removing crystalline alkyl sulfuric acid from said fluid reaction product to a neutralization zone wherein the crystals are neutralized to a pH greater than 8 by a strong base, thereby forming a crystalline alkyl sulfate product rich in 2- alkyl sulfate, and
(C) continuously removing crystallization medium from said neutralized crystalline alkyl sulfate product.
CHARLES B. PARKER, Primary Examiner.
;- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,234,258 February 8, 1966 Robert Louis Morris It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.
Column 1, line 15, for "sulur" read sulfur line 56, for "sulfated" read unsulfated column 3, line 50, for "oragnic" read organic column 7, line 14, after "offset" insert any line 71, for "deccribed" read described column 10, line 12, after "Olefin" insert flow column 11, line 23, for "H 50 read H 50 Signed and sealed this 17th day of January 1967.
ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents