Claims:1. A method for synthesis of tertiary butyl phenol or octyl phenols or mixtures of various alkyl phenols using one or more compounds of isobutene, characterized in that, said method comprising the steps of;
a) charging phenol to the reactor and heating to requisite temperature;
b) adding a catalyst AlCl3, Clay, Tonsil or Ion Exchange based on estimated reaction mixture and maintaining the temperature;
c) adding oligomer mixture or compounds of isobutene in equal pre-decided aliqotes, of proper concentration, at pre-decided time interval and pre-decided stages;
d) cooling after step (c) and treating the reaction mixture to separate catalyst from the same;
e) analyzing to estimate concentration of reaction products in reaction mixture appropriately by Gas chromatography-Mass spectrometry (GCMS);
wherein said one or more compound of isobutene comprises: an oligomer mixture, dimers of isobutene, a pre-defined quantity of dimer and trimer of isobutene, wherein said one or more compounds of isobutene is selected from the group consisting of methyl tertiary butyl ether and tertiary butyl alcohol of pre-defined purity level;
wherein a mole ratio of phenol to said one or more compounds of isobutene is gradually reduced from a highest mole ration to a lowest mole ratio by adding a pre-defined quantity of one or more compounds of isobutene;
wherein said pre-defined reaction temperature is a range of 90°C to 160°C;
wherein said pre-defined weight of said catalyst is in a range of 0.1% - 10 % of the pre-defined weight of said phenol and oligomer or phenol and compound of isobutene;
wherein said pre-defined time interval is in a range of 1 minute to 60 minutes;
wherein said plurality of stages is pre-decided to suit the reaction; and
wherein the steps ( a ) – ( e ) are performed within a reaction time in a range of 3 hours to 6 hours.

2. The method as claimed in claim 1, wherein said lowest mole ratio of phenol to one or more compounds of isobutene is 2:1.

3. The method as claimed in claim 2, wherein said highest mole ratio of phenol to said one or more compounds of isobutene is 50:1.

4. The method as claimed in claim 3, wherein said preferred highest mole ratio of phenol to said one or more compounds of isobutene is 30:1 to 20:1

5. The method as claimed in claim 1, wherein said quality of dimer in said one or more compounds of isobutene is in a range of 10% to 100% and 90% or more for one or more other compounds of isobutene, of said pre-defined quantity of said one or more compounds of isobutene.

6. The method as claimed in claim 5, wherein said quality of dimer is preferably in a range of 60% to 100% and 98% or more for one or more other compounds of isobutene, of said pre-defined quantity of said one or more compounds of isobutene.

7. The method as claimed in claim 1, wherein said pre-defined time interval is in a range of 5 minutes to 15 minutes.

8. The method as claimed in claim 1, wherein said catalyst is selected from the group consisting of Lewis acid catalyst and modified Lewis acid catalyst, wherein said catalyst is selected from the group consisting of AlCl3, Clay, Tonsil, and Ion-exchange Resins, wherein said pre-defined weight of said catalyst is in a range of 1% - 5 % weight of reaction mixture.

9. The method as claimed in claim 1, wherein said plurality of stages is at least 15 stages or pre-decided to suit the reaction.

10. The method as claimed in claim 1, wherein said reaction time is in a range of 3 hours to 6 hours.
, Description:FIELD OF THE INVENTION
Embodiments of the present invention generally relates to an efficient and novel method for the synthesis of alkyl phenols using compounds of isobutene. In particular to a method of synthesis of tertiary butyl and octyl phenol, or mixtures of various alkyl phenols, mono- or di-substituted alkyl phenols using dimer of isobutene or dimer and trimer mixture of isobutene, the dimer or dimer-trimer mixture either specifically synthesized or resulting as by-product / co-product of polymerization reactions, or one or more compounds like methyl tertiary butyl ether (MTBE) or tertiary butyl alcohol.
BACKGROUND OF THE INVENTION
Alkylation is a chemical process by which an alkyl group is attached to an organic substrate molecule via addition or substitution and has importance in a variety of applications in chemical industry including synthesis of alkyl phenols.
Alkyl phenols are mainly used as raw materials in the production of a variety of industrial products such as surfactants, detergents, phenolic resins, polymer additives and lubricants. The most common route for the production of alkyl phenols is by alkylation of phenols with alkene, with di-isobutylene, propylene trimer and propylene tetramers, respectively, under acidic conditions. One of the major uses of isobutene is in alkylation reactions to produce various alkylated species including pharmaceutical intermediates. The normal alkylation per textbook, are carried out using Friedel-Craft reaction, developed by Charles Friedel and James Craft in 1877 to attach substituents to an aromatic ring, using Lewis-Acid catalysts of various types, AlCl3 being prominent one. While in most cases use of isobutene either pure or in the raffinate containing other hydrocarbons, or isobutene liberated from compounds like methyl tertiary butyl ether, are used and found useful, there is limited literature on use of compounds of isobutene such as oligomers, alkyl ethers of isobutene or alcohols of isobutene to cite few, for alkylation by using very high mole ratio of components in a limited volume of reactants.
In one of the closest relevant arts, US 2091565 (1935) discloses a method for preparation of tertiary butyl phenol. An alkylated aromatic compound, like alkyl phenol, can be synthesised by reacting an aromatic compound with an olefin corresponding to the alkyl group to be introduced into the aromatic ring. (for example, Annales de Chimie, Ser. 10, voi. 11, pages 550-556, 10). Also, in Serial No. 737,813, filed July 31, 1934, as refereed in the same document, it is disclosed that a poly(olefin)s like di-isobutylene, react with phenol in the presence of a Friedel-Crafts catalyst, at a temperature below 90° C, to produce the corresponding alkylated phenol, i. e., tertiary octyl phenol, in good yield. Di-isobutylene, tri-isobutylene, etc., or mixtures thereof, are reacted with phenol at a temperature above 90° C., to obtain tertiary butyl phenol as major product instead of tertiary octyl phenol. In synthesis of tertiary butyl phenol from di-isobutylene and phenol by this invention, a mixture of compounds in any ratio is heated to a reaction temperature above 90° C., preferably between 110 and 190° C., in the presence of a Friedel–Crafts catalyst. The di-isobutylene and phenol may be reacted in any proportions, but the reaction proceeds satisfactorily when an excess of the phenol is used. The catalyst can be used in any desired proportion, but is preferred at 1 per cent to 10 per cent of the weight of phenol. Catalysts which may be used are AlCl3, AlBr3, FeCl3, SnCl4, or an acid-activated bleaching earth such as tonsil, Super-Filtrol, etc. The reaction is usually carried out under reflux at atmospheric pressure, but may be carried out under elevated pressures in a closed reactor, if necessary. After completing the reaction, the mixture is cooled and the catalyst removed or destroyed by usual procedure, e.g., by treatment with water, an aqueous base, or an aqueous acid Solution. The mixture is then distilled to separate the tertiary butyl phenol.
Another relevant art US 4166191 (1979) discloses a process for producing highly pure p-tertiary-butyl phenol. The highly pure p-tertiary-butyl phenol is prepared from an olefin composition comprising a major amount of at least one isobutylene oligomer and a minor amount of a co-dimer of n-butene and isobutylene. The reaction of said olefin composition with phenol is carried out in the presence of water and synthetic silica-alumina catalyst at a temperature of 140°-230° C.
Another relevant art US20110118160 A1 (2009) discloses an alkylated hydroxy aromatic compound substantially free of endocrine disruptive chemicals. The alkylated hydroxy-aromatic compound is prepared by reacting at least one hydroxy aromatic compound with at least one branched olefinic propylene oligomer having from about 20 to about 80 carbon atoms in the presence of an acid catalyst, wherein the at least one branched olefinic propylene oligomer is substantially free of any vinylidene content. The alkylated hydroxy aromatic compound has been defined to be substantially free of endocrine disruptive chemicals when the effects were quantified on pubertal development and thyroid function in the intact juvenile female rat.
Another relevant art US 5171896 A (1992) discloses an alkyl phenol synthesis using acid-modified inorganic clay catalysts. In particular, the relevant art discloses a one-step method for synthesis of alkyl phenols which comprises reacting phenol with the corresponding olefin under adiabatic conditions in the presence of a catalyst comprising an acidic montmorillonite clay having the structure:
Mx/nn+.yH2O(Al4-xMgx)(Si8)O20(OH)4
where M represent the interlamellar (balancing cation, normally sodium or lithium) and x, y and n are integers, wherein the acidic clay has been pretreated with an acid and optionally has deposited thereon an acid selected from the group consisting hydrogen fluoride, a fluorosulfonic acid or a mineral acid, at a temperature of from 60 degree C to 250 degree C and a pressure of from near atmospheric to about 500 psi.
Another relevant art US4138591 A (1979) discloses a method for manufacture of alkyl phenols. The relevant art discloses that Alkylphenols are manufactured by reacting phenols with olefins, stripping the reaction mixture by means of an inert gas, cooling the phenol-containing gas mixture and removing the unconverted phenol. The products are starting materials for the manufacture of dyes, pesticides, pharmaceuticals, emulsifier, dispersing agents, stabilizers, antioxidants, plasticizers, corrosion inhibitors, disinfectants, seed dressings, and stabilizers against ageing, crop protection agents and scents.
Another relevant art US 5334775 A (1993) discloses a process for alkylating hydroxy aromatic compounds with a terminally unsaturated polymer in the presence of a partially or completely dehydrated heteropoly catalyst. The alkylated hydroxy aromatic compounds so formed are useful as precursors for the production of fuel and lubricant additives.
Another relevant art EP3472274A2 (2017) discloses a polyisobutylene-substituted hydroxy aromatic compound and derivatives thereof which are suitable for use as additives in lubricating compositions. The polyisobutylene-substituted hydroxy aromatic compound may include the reaction product of a hydroxy aromatic compound with a polyisobutylene having a number average molecular weight of 150 to 800.
Another relevant art JPS61251633 A (1985) discloses a process for the production of highly pure p-tert-butyl phenol by reacting a mixed gas mainly containing isobutylene and n-butene is reacted with phenol in the presence of activated clay catalyst at 10-120 deg C (preferably 30-80 deg C), and the raw material mixed gas dissolved in an alkylation reaction solution is removed by discharging or blowing an inert gas, exchanging the used catalyst with new activated clay to carry out rearrangement reaction while continuing blowing the inert gas to obtain the titled substance. The rearrangement reaction is carried out at 50-200 deg C (preferably 80-130 deg C) for 1-5hr.
Another relevant art US7030285 B2 discloses an alkylation process. In particular, alkylation of a side-chain of a substituted aromatic compound by reacting the aromatic compound with an alkylating agent in the presence of a catalyst. The catalyst comprises a re-structured smectite clay to which basic ions are incorporated by ion-exchange. The restructuring of the smectite clay is carried out by acid-treating the clay prior to ion-exchange.
Similarly, several other literatures (US Patent 9434668B1) indicate use of methyl tertiary butyl ether- a compound of isobutene used for synthesis of para-tertiary butyl phenol using a specially made catalyst.
Patent Number US 5399786 also uses methyl tertiary butyl ether reacting with phenol and also trans-alkylation processes, where the process itself can be continuous or intermittent or a mix of both intermittent and continuous etc.
The prior arts described indicate the use of excess phenol, higher temperatures, which limit its application for industrial or bulk application. Owing to the presence of very high amount of phenol, separation of components of reaction product is a challenge.
Accordingly, there remains a need for an efficient and novel method for the synthesis of alkyl phenols in order to overcome the problems, disadvantages and the limitations of the above-mentioned relevant and conventional arts are being overcome by the method and composition of the present invention, which has various technical advancements and certainly economic benefits over the conventional arts.

SUMMARY OF THE INVENTION
In order to verify which of the parameters principally impact a common reaction like between phenol and alkylating agents, we used a traditional catalyst AlCl3 to study reaction between Phenol and Oligomer albeit with lower concentration of dimer (37%). The reactions were carried out in a regular flask with usual assembly and the resultant reaction mixtures were analyzed by GC after appropriate treatment with mild alkali (aqueous Na2CO3) and dissolving mixture in toluene to inject into a GCMS instrument.
Conversion Calculations
For 3:1 Mole Ratio of Phenol to Dimer –
141 gm Phenol (1.5 moles) + 4.5 gm AlCl3 (0.03 moles) + 151.4 gm oligomer (37% dimer or 56 gm dimer or 0.5 moles) = Total 292.4 gm (as AlCl3 will be neutralized to remove at the end)
Area in GC should be theoretically.
All converted to ortho tertiary Butyl Phenol, Area = (150/292.4) x 100 = 51.36%
All converted to para tertiary Butyl Phenol, Area = (150/292.4) x 100 = 51.36%
All converted to Octyl Phenol, Area = (103/292.4) x 100 = 35.22%
If Areas in GCMS are 11.2% para-, 1.3% ortho- and 32.7% then conversions are
para = (11.2/51.36) x 100 = 21.90 % of theory
ortho = (1.3/51.36) x 100 = 2.53 % of theory
octyl = (32.7/35.22) x 100 = 92.84 % of theory
Calculation for 2:1 Mole Ratio of Phenol to Dimer –
141 gm Phenol (1.5 moles) + 4.5 gm AlCl3 (0.03 moles) + 227 gm oligomer (37% dimer or 84 gm dimer or 0.75 moles) = Total 368 gm (as AlCl3 will be neutralized to remove at the end)
Area in GC should be
All converted to ortho tertiary Butyl Phenol, Area = (225/368) x 100 = 61.14%
All converted to para tertiary Butyl Phenol, Area = (225/368) x 100 = 61.14%
All converted to Octyl Phenol, Area = (154.5/368) x 100 = 42.00%
If Areas in GCMS are 11.2% para-, 1.3% ortho- and 32.7% then conversions are
para = (11.2/61.14) x 100 = 18.31 % of theory
ortho = (11.2/61.14) x 100 = 18.31 % of theory
octyl = (32.7/42.00) x 100 = 77.86 % of theory
% Conversion on Phenol = In a mixture even though, unreacted phenol can be detected and % reacted theory phenol can be calculated it will not indicate which products it has formed. Moreover, higher amounts of phenol will remain unreacted for formation of octyl-phenol or di-tertiary butyl phenols, however it indicates remaining phenol that needs to be distilled out.

These experiments were carried out in duplicate using DOE (Design of Experiments) similar to Taguchi L8 orthogonal arrays, with 2 levels - high and low; 3 factors Mole Ratio (A), Reaction Time (B) and Temperature (C). The results are tabulated in Table 1.
Figures 1 to 3 show the same results pictorially.
In all the three Figures, A = Mole Ratio, B = Reaction Time, C = Temperature, A*B, A*C, B*C show impact of interactions of parameters. It shows, higher mole ratio of Phenol to oligomer increases conversion to para-tertiary-butyl phenol and para-octyl phenol and reduces formation of ortho-tertiary-butyl phenol. Similar observations are for reaction time. While increasing the temperature has not much impact on conversion to para-tertiary butyl phenol, but decreases the formation of ortho-tertiary butyl phenol and octyl phenol. Similarly increase in mole ratio and reaction time together increases conversion of para-tertiary-butyl phenol and decreases octyl phenol has very small impact on ortho-tertiary butyl phenol.
Therefore, the major parameters impacting the efficient synthesis of alkyl phenols using one or more compounds of isobutene are mole ratio of phenol to dimer, reaction time and reaction temperature.
The objective of the present invention is to provide a method for the efficient preparation of alkyl phenols using compounds of isobutene.

Another objective of the present invention is able to facilitate reactions efficiently by incorporating optimum and reasonable amounts of reactants that results in maintain high mole ratio of reactants. Further object of the present invention is able to facilitate efficient reactions in an optimized reaction vessel of reasonable size and in isothermal conditions rather than adiabatic conditions.

In one aspect of the present invention, the disclosed method comprising the step of addition of one of the reactants in small aliquots to reaction mixture to start the reaction at high molar ratio, and subsequently decreasing mole ratio as the reaction proceeds to result in desired products. The method disclosed reduces the need for distillation of excess reactants as compared to the methods disclosed in the relevant art.

In second aspect of the present invention, a method for synthesis of tertiary butyl phenol or octyl phenols or mixtures of various alkyl phenols using one or more compounds of isobutene is disclosed herein. The method disclosed herein comprises the step of:
a) adding a pre-defined amount of phenol to a reaction vessel along with a catalyst;
b) heating of said reaction vessel to a pre-defined reaction temperature; and
c) adding equal amount of one or more compounds of isobutene at desired stages to said reaction vessel after completion of step (b) and at a pre-defined time interval.
In another aspect of the present invention, the one or more compounds of isobutene may be an oligomer mixture comprising of dimers of isobutene and mixture dimer/trimer of isobutene ranging from 10% to 100% of the mixture as dimer and remaining 90% to 0% of trimer and small amounts of other one or more compounds of isobutene. More preferably the concentration of dimer is at least 30% and at most more than 60% of the mixture. Similarly other compounds of isobutene used may be of approximate purity level of > 90% and preferably > 98%, and may also be in a crude undistilled stage which may comprise of lower purity levels.
In another aspect of the present invention, the addition of one or more compounds of isobutene at desired stages to the reaction vessel is carried out at a pre-defined time interval ranging from 1 minute to 60 minutes, more preferably at an interval range of 5 minutes to 15 minutes.
In another aspect of the present invention, the method for synthesis of alkyl phenols using one or more compounds of isobutene by maintaining a higher ratio of phenol to one or more compounds of isobutene at the beginning of the reaction and gradually reducing the ratio by adding a pre-defined amount of one or more compounds of isobutene as the reaction progressed to a maximum mole ratio of 2:1 of theoretically unreacted phenol to one or more compounds of isobutene. Therefore, the method allows maintaining a high mole ratio of phenol to one or more compounds of isobutene. Initially a higher mole ratio of phenol to one or more compounds of isobutene is maintained which is approximately 50:1 and preferably a mole ratio in a range of 30:1 to 20:1.
In another aspect of the present invention, the method for synthesis of tertiary butyl phenol or octyl phenols or mixtures of various alkyl phenols using one or more compounds of isobutene is carried out at a pre-defined reaction temperature ranging between 80°C and 200°C, and more preferably in the range of 90°C to 160°C.
In another aspect of the present invention, the catalyst used is a Lewis acid or a modified Lewis acid catalyst selected from the group consisting of, but not limited to AlCl3, Clay, Tonsil, and Ion-exchange Resins. The weight of the catalyst present is in the range of 0.1% to 10% by weight of reactants in said reaction vessel, preferably 0.5% to 5% and more preferably in range of 1% to 5% by weight of the reactants.
In yet another aspect of the present invention, the reaction between phenol and one or more compounds of isobutene is carried out for a reaction time in range of 3 hours to 24 hours, more preferably 3 hours to 6 hours.
In yet another aspect of the present invention, the disclosed method can be extended to other reactions where the ratio of reactants needs to be maintained at a higher mole ratio.
The present invention achieves each of the above-stated objectives and overcomes the foregoing disadvantages and problems. These and other objectives and other features and advantages of the invention will be apparent from the detailed description, referring to the attached tables, and from the claims. Thus, other aspects of the invention are described in the following disclosure and are within the ambit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS
An exemplary embodiment of the present invention is illustrated by way of example in the accompanying drawings in which like reference numbers indicate the same or similar elements in which:
FIG. 1 illustrates an impact of reaction parameters on % conversion of p-tert-butyl phenol, according to one or more embodiments.
FIG. 2 illustrates an impact of reaction parameters on % conversion of o-tert-butyl phenol, according to one or more embodiments.
FIG. 3 illustrates an impact of reaction parameters on % conversion of p-octyl phenol, according to one or more embodiments.
FIG. 4 illustrates an example reaction between dimer and phenol- pure and mixture with octyl phenol, according to one or more embodiments.
FIG. 5 illustrates an example reaction between methyl tertiary butyl ether and phenol, according to one or more embodiments.
FIG. 6 illustrates a typical GC-MS graph of reaction mixture, according to one or more embodiments.
FIG. 7 illustrates typical FTIR spectra of reaction mixture, according to one or more embodiments.

DETAILED DESCRIPTION OF THE INVENTION
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The description used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the description or explanation should not be construed as limiting the scope of the embodiments herein.
Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims. The terms like can be, shall be, could be, and other related terms herein disclosed in the foregoing and later parts of the specification in any means do not limit or alter the scope of the present invention. The terms are provided just for the mere understanding of the main invention and its embodiments.
The specific embodiments of the present invention are disclosed herein below, which relate to method for efficient synthesis of tertiary butyl phenol or octyl phenols or mixtures of various alkyl phenols, mono- or di-substituted alkyl phenols, using one or more compounds of isobutene or dimer and trimer mixture of isobutene, the dimer or dimer-trimer mixture either specifically synthesized or resulting as by-product / co-product of polymerization reactions or one or more compounds of isobutene like methyl tertiary butyl ether or tertiary butyl alcohol.
In accordance with an embodiment of the present invention, the method disclosed herein includes multiple novel features that include incorporating optimum and reasonable amounts of reactants that results in maintaining a high mole ratio of reactants. Particularly, the innovative feature of addition of one of the reactants in small aliquots to start the reaction at high molar ratio, and subsequently decreasing mole ratio as the reaction proceeds to result in desired products. The method disclosed reduces the need for distillation of excess reactants as compared to the methods disclosed in the relevant art.

In accordance with an embodiment of the present invention, the disclosed method is able to facilitate efficient reactions in an optimized reaction vessel of reasonable size and in isothermal conditions rather than adiabatic conditions.

In the following examples, the tertiary butyl phenol or octyl phenols or mixtures of various alkyl phenols using one or more compounds of isobutene can be prepared by the following method:
(a) heating phenol to melt;
(b) charging phenol to a round bottom flask by weighing the flask, taring and taking net weight;
(c) adding a catalyst such as AlCl3, clay, tonsil or ion exchange resin once again by taring the round bottom flask and adding to obtain a net weight of catalyst nearest to decided amount.
(d) assembling the reaction set up, round bottom flask and condenser;
(e) heating the flask to desired temperature as required by catalyst activity;
(f) adding Oligomer mixture (between 10 -100% concentration), or methyl tertiary butyl ether (at least 90% concentration) at pre-decided interval of time, pre-decided weight and pre-decided stages;
(g) carrying out the reaction to desired stages and time;
(h) after completion of step (g), cooling the reaction mixture and allow to settle;
(i) drawing a small supernatant sample and dissolving in toluene;
(j) analyzing the solution obtained from step (i) by Gas chromatography-Mass spectrometry (GCMS).

In one embodiment of the present invention, one or more compounds of isobutene–specifically the oligomer mixture further comprises dimers of isobutene and mixture dimer/trimer of isobutene defined ranging from 10% to 100% by weight of the mixture as dimer, and remaining 90% to 0% of trimer and small amounts of other oligomers of isobutene. More preferably the pre-defined quantity of dimer is at least 30% and preferably more than 60% of the mixture. Other compounds of isobutene used in the reaction may desirably have 90% or more purity level and preferably more than 98% purity level.
In another embodiment of the present invention, the addition of one or more compounds of isobutene compounds at desired stages to the reaction vessel is carried out at a pre-defined time interval between 1 minute to 60 minutes, more preferably at a range of 5 minutes to 15 minutes time interval.
In another embodiment of the present invention, the method for synthesis of alkyl phenols using one or more compounds of isobutene comprises the step of reacting one or more compounds of isobutene by maintaining higher ratio of phenol to one or more compounds of isobutene at the beginning of reaction and gradually reducing the ratio by addition of a pre-defined amount of one or more compounds of isobutene as the reaction progresses to a maximum mole ratio of 2:1. Initially a higher mole ratio of phenol to one or more compounds of isobutene is maintained which is approximately 50:1 and preferably a mole ratio in a range of 30:1 to 20:1.
In another embodiment of the present invention, the method for synthesis of tertiary butyl phenol or octyl phenols or mixtures of various alkyl phenols using compounds of isobutene is carried out in a pre-defined reaction temperature ranging between 80°C and 200°C, and more preferably in the range of 90°C to 160°C.
In another embodiment of the present invention, the catalyst used is a Lewis acid or a modified Lewis acid catalyst selected from the group consisting of, but not limited to AlCl3, Clay, Tonsil, and Ion-exchange Resins. The weight of the catalyst present is in the range of 0.1% to 10% by weight of reactants in said reaction vessel, preferably 0.5% to 5% and more preferably in the range of 1% to 5% by weight of the reactants.
In yet another embodiment of the present invention, the reaction between phenol and one or more compounds of isobutene is carried out for a reaction time in range of 3 hours to 24 hours, more preferably 3 hours to 6 hours.
Examples
The present examples provide a method for synthesis of tertiary butyl phenol or octyl phenols or mixtures of various alkyl phenols using one or more compounds of isobutene, specifically comprising the following steps: (a) reacting phenol and one or more compounds of isobutene in presence of traditional AlCl3 Catalysts or modified acidic catalysts such as clay and tonsil or ion-exchange. (b) The mixture obtained after step (a) is dissolved in fixed quantity of toluene. (c) the solution obtained in step (b) is washed in fixed amount of Na2CO3 (aq.) or settled and decanted as necessary and subjected to GC-MS (Gas chromatography-Mass spectrometry) analysis. All reaction with AlCl3 (120°C), Clay (150°C), Tonsil (150°C) and Ion-exchange resin (130°C) were carried out for a time duration of 225 minutes – almost 4 hours. Reaction is carried out using distilled mixture of one or more compounds of isobutene to increase the concentration of dimers to a purity level of 30 -100 % or with one or more compounds of isobutene having a purity level of greater than 90 % in a flask with agitation / stirring and in an open system like the one used for studying impacting parameters mentioned above. The condenser is circulated with water to minimize evaporation of vapor during the process.
The experiment may be performed in multiple stages for example in the current example, a fifteen-stage experiment is conducted. In an embodiment, the experiment may be conducted in any number of stages. Each stage includes adding a pre-defined amount of phenol to the reaction vessel along with a preferred catalyst. Once the temperature of the reactants increases to a pre-defined temperature equal amounts of oligomer containing dimer which is 10-100% in purity level or isobutene compounds of at least 90% purity are added. A mole ratio of Phenol to dimer (or one or more compounds) of isobutene added is calculated as mentioned in the Table 2 at each stage. In an embodiment, it is assumed that for each stage of the reaction, one mole unit of dimer is reacted with 2 equal moles of phenol for synthesis of alkyl phenol. According to traditional methods used in the relevant art, in order to achieve a molar ratio of phenol to one or more compounds of isobutene of 30:1 2115 gm of phenol (for 0.75 moles dimer x 30 x 94) is required and is difficult to remove the unreacted Phenol from the reaction mixture. However, in the present examples the molar ratio of 30:1 is achieved by using 141 gm phenol.
The result analysis indicates that the reaction temperature is dependent on the characteristic of the catalyst used. Also Figures 4 and 5 indicate possible mechanisms of product synthesis and Figure 6 and 7 show the GC-MS and FTIR spectra of reaction mixture. Table 3 indicates the results calculated on the basis of molecular entities found in GC-MS. The percentage (%) conversion is calculated on the principles as shown earlier. Conversion beyond 100% based on dimer indicates some amount of trimer also reacting in due course of time. Hence any conversion beyond 100% based on dimer is to be expected as an extra trimer getting converted and contributing to the reaction. Table 4 shows summary.
Calculation for 30:1 mole ratio of Phenol to Dimer (Example Dimer = 67% concentrate in oligomer)
Stage 1 ? 141 gm Phenol (1.5 moles) + 5.6 gm dimer (0.05 moles), Ratio = 30
Stage 2 ? reacted dimer assumed = 0.05 (theory). Each 0.05 mole liberates 0.1 mole of isobutene, assuming 100% reaction with Phenol it will consume 0.1 mole of phenol, remaining phenol 1.4 moles (131.6 gm) + 0.05 moles of dimer (5.6 gm) and so on for remaining stages.
Reaction Time ? Normally absorption of isobutene in Phenol is about 0.1 moles / mole of Phenol at about 100*C at 15 minutes interval. Since dimer liberates isobutene to react with Phenol it is assumed that a time period of 15 minutes is reasonable, but can be adjusted based on observations.
Reaction Temperature ? This purely depends on catalyst used.
Similar calculations can be performed for other mole ratios like 50:1 or 20:1 or any other.
Differences between normal reaction between Phenol + Oligomers and step wise addition –
The direct reaction yields more octyl phenol in 4 – 6 hrs. time period, the stepwise addition gives mixture of para-tertiary butyl phenol and octyl phenol. The octyl phenol can be either converted in-situ to tert-butyl phenol by heating with excess phenol or can be separately treated.
To cite an example of one or more compounds of isobutene that can be reacted in a similar manner, Table 5 indicates reaction of phenol with methyl-tertiary butyl ether in a 15 stage reaction and Table 6 summarises the same. By adding 0.067 moles of methyl- tertiary butyl ether in each stage and following same steps as above for an ion-exchange catalyst, the mole ratio of phenol to methyl-tertiary butyl ether will vary from 22:1. to 8:1. Notingly, 0.5 moles of phenol which was added in excess should remain unreacted in the end of the reaction

Similar to dimer, for methyl tertiary butyl ether calculations can be performed.
Amount of Phenol = 1.5 moles = 141 gm, MTBE Total = 88 gm as reaction is between 1 mole of Phenol and 1 mole of MTBE. Ratio for normal reaction = 1.5 to 1. For Stepwise reaction for 15 stages of example.
Stage 1 ? 141 gm Phenol (1.5 moles) + 5.86 gm MTBE (0.066 moles) Ratio = 22.7
Stage 2 ? Assuming 0.066 moles reacted, remaining Phenol = 1.434 added MTBE = 0.066 Ratio = 21.72 like continue to calculate

Calculations (MTBE)
This method cannot yield octyl phenol easily as there is no octyl group involved, so reaction can be ortho- and para-tertiary butyl phenol as well as di- and tri- substituted phenols.
Total Weight = 229 gm. Expected butyl phenol = 1 mole based on MTBE = 150 gm. If conversion is 100% for butyl phenols, then % butyl phenol in mixture = 150 / 229 = 65.50%. If everything is converted to di-tertiary butyl phenol then % = 206 / 229 = 90% approximately.
Conversion of phenol as usual just indicates numbers that converted to all types of products and can be used to estimate phenol that needs to be separated from mixture.
If GC analysis shows, 30.7% Phenol, 27.89% ortho tertiary butyl phenol, 27.46% para-tertiary butyl phenol and 13.65% 2,4, di-tertiary butyl phenol,
ortho = (27.89/65.5) x 100 = 42.58 % of theory
para = (27.46/65.5) x 100 = 41.92 % of theory
2,4, dtbp = (13.65/90) x 100 = 15.16 % of theory

Tables
Table 1: DOE for conversion to OTBP, PTBP and C8-PhOH*
Mole Ratio Rxn Time Rxn Temp Conv % Conv % Conv %
Batch PhOH:Dimer Hrs *C OTBP PTBP C8-PhOH
Lab-2020-218 3 to 1 4 90 1.9 3.6 95
Lab-2020-222 2 to 1 4 90 2.2 1.1 32.2
Lab-2020-219 3 to 1 6 90 1.3 4.6 96.6
Lab-2020-223 2 to 1 6 90 2.4 1 32.9
Lab-2020-220 3 to 1 4 120 1 17.8 81.2
Lab-2020-224 2 to 1 4 120 2.4 3.2 80.2
Lab-2020-221 3 to 1 6 120 1 18.1 84.5
Lab-2020-225 2 to 1 6 120 1.3 2.4 51.2
Lab-2020-226 3 to 1 4 90 1.1 5.9 99.9
Lab-2020-229 2 to 1 4 90 2.5 1.4 35
Lab-2020-236 3 to 1 6 90 1.4 5 86.9
Lab-2020-232 2 to 1 6 90 2.7 1.3 31
Lab-2020-227 3 to 1 4 120 1.1 19.1 76.4
Lab-2020-230 2 to 1 4 120 2.5 2.9 88.2
Lab-2020-228 3 to 1 6 120 1.2 18.4 72.6
Lab-2020-234 2 to 1 6 120 1.7 5.5 85.8

*where OTBP = ortho-tertiary butyl phenol, , PTBP = para-tertiary-butyl phenol and C8-PhOH = para-octyl phenol and are used in below text to indicate respective compounds.
Table 2: Scheme for 15 stage experiment between phenol and isobutene dimer is as follows:
Reactants
Stages Balance Phenol
(Moles) AlCl3
(Moles) Dimer
(Moles) Theory Ratio
(Moles)
Stage 1 1.50 0.03 0.05 30.00
Stage 2 1.40 0.05 28.00
Stage 3 1.30 0.05 26.00
Stage 4 1.20 0.05 24.00
Stage 5 1.10 0.05 22.00
Stage 6 1.00 0.05 20.00
Stage 7 0.90 0.05 18.00
Stage 8 0.80 0.05 16.00
Stage 9 0.70 0.05 14.00
Stage 10 0.60 0.05 12.00
Stage 11 0.50 0.05 10.00
Stage 12 0.40 0.05 8.00
Stage 13 0.30 0.05 6.00
Stage 14 0.20 0.05 4.00
Stage 15 0.10 0.05 2.00

TABLE 3: The operating parameters and analysis results for 15 stage experiments as follows:
Expt # Purity Lab-2020-265 Lab-2020-266 Lab-2020-267 Lab-2021-273 Lab-2021-274 Lab-2021-275
% gm gm gm gm gm gm
Reactants
Phenol 99 141.0 141.6 141.3 141.3 141.3 141.5
Catalyst 99 4.5 4.5 4.2 4.3 4.6 5.1
Dimer 67 84.0 84.0 84.0 84.0 84.0 84.0
Catalyst AlCl3 AlCl3 AlCl3 Clay Clay Clay
Temp*C 120 120 120 155 155 155
Time Hr. ~4.0 ~4.0 ~4.0 ~4.0 ~4.0 ~4.0
GCMS Area %
Phenol 28.03 25.20 32.17 34.52 34.64 32.98
Dimer
p-tert-BuPhOH 15.235 12.27 14.35 35.66 32.3 36.114
p-C5-PhOH 3.802 3.298 2.767 13.1 15.56 13.866
p-C8-PhOH 48.453 47.269 46.94 16.72 17.5 17.032


Actual Conversion
Based on unreacted Phenol* 55.27 59.85 48.70 44.96 44.77 47.44

Expt # Purity Lab-2021-277 Lab-2021-281 Lab-2021-283 Lab-2021-302 Lab-2021-303 Lab-2021-304
% gm gm gm gm gm gm
Reactants
Phenol 99 141.6 141.5 141.1 141.1 141.1 141.1
Catalyst 99 4.2 4.5 4.6 4.6 4.6 4.6
Dimer 67 84.0 84.0 84.0 84.0 84.0 84.0
Catalyst Tonsil Tonsil Tonsil Ion Exchange Ion Exchange Ion Exchange
Temp*C 155 155 155 130 130 130
Time Hrs ~4.0 ~4.0 ~4.0 ~4.0 ~4.0 ~4.0
GCMS Area %
Phenol 22.85 15.90 17.50 26.11 21.67 19.74
Dimer
p-tert-BuPhOH 14.84 10.2 12.3 38.086 34.263 30.626
p-C5-PhOH 4.04 4.19 7.45 4.342 1.61 3.487
p-C8-PhOH 58.27 69.7 62.75 31.465 42.225 46.143


Actual Conversion
Based on unreacted Phenol 63.59 74.66 72.08 58.35 65.43 68.50

TABLE 4: The average % conversion calculated based on GCMS:
Catalyst ? AlCl3*
Average Conversion % Clay*
Average Conversion % Tonsil*
Average Conversion % Ion Exchange*
t-Bu-PhOH* 18.3 45.5 16.3 44.94
Oct-PhOH* 106.9 38.4 143.0 89.69
PhOH** 54.6 45.7 70.0 64.09

Table 5: The results (in %) calculated on the basis of molecular entities found in GC-MS are as follows:
Expt # Purity Lab-2021-311 Lab-2021-313 Lab-2021-316
% gms gms gms
Reactants
Phenol 99.00 143.20 141.70 158.000
Catalyst 99.00 2.00 2.10 2.100
MTBE 99.00 86.80 87.50 87.6
Catalyst Ion-Exchange Clay Tonsil

Temp *C 130 155 155
Time ~ 4 hr ~ 4 hr ~ 4 hr

GCMS Area %
PhOH 30.71 21.04 27.502
o-tert-Bu-PhOH 27.89 19.03 20.846
p-tert-Bu-PhOH 27.46 33.96 35.673
2,4-diTBP 13.649 21.97 15.97
2,6-diTBP 0.061

Actual Conversion
Based on unreacted PhOH 50.67 65.97 57.25

TABLE 6: The average % conversion to theory calculated based on GCMS:
Catalyst ? Ion Exchange Clay Tonsil
o-t-Bu-PhOH 39.4 24.5 27.8
p-t-Bu-PhOH 36.3 48.9 49.5
di-t-Bu-PhOH 16.7 21.7 8.1
PhOH 52.1 62.0 52.4

While there has been shown and described the preferred embodiment of the instant invention it is to be appreciated that the invention may be embodied otherwise than is herein specifically shown and described and that within said embodiment, certain variations, modifications, and equivalent arrangements may be made in the form and arrangement of the parts without departing from the underlying ideas or principles of this invention as set forth in the claims appended herewith.
Accordingly, while the present invention has been described herein in detail in relation to one or more preferred embodiments, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for the purpose of providing a full and enabling disclosure of the invention. The foregoing is considered illustrative of only the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
The foregoing discussion is illustrative of the invention. However, since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides wholly in the claims hereinafter appended.