200536818 (1) 九、發明說明 相關申請案之參照 本申請案係2004年八月9日提出申請的申 10/915,723之後續申請案，該案主張2004年3 j 請的臨時專利申請案序號第60/5 5 6,23 6號在35· 1 19(e)下之優先權。 【發明所屬之技術領域】 本發明係有關製造高純度酚之領域。更特定 發明係有關從酚去除乙醯甲醇以獲得合意的高純丨 【先前技術】 常用於製造酚的方法包含將異丙苯氧化爲氫 丙苯，接著其酸催化分解爲酚與丙酮。從反應產 係包含酸催化劑的中和，接著一系列蒸餾與分離 φ 低沸點成分，例如丙酮，未反應的異丙苯與α-甲 (AMS)首先藉由蒸餾從粗製產物回收。剩餘物質 至酚回收管柱中，於其中從較高沸點雜質蒸餾出 於回收丙酮、異丙苯、與AMS所用的蒸餾程序 出的酚除了殘餘量的丙酮、異丙苯與AM S之外 包含少量雜質，例如異亞丙基丙酮（mesityl oxid 、乙醯甲醇（羥基丙酮）、及其他脂族羰基化合 化合物、苯乙酮、異丙苯酚（c u m y 1 P h e η ο 1 )、與 甲基苯并呋喃（MBF )。此等雜質在某些應用， 請案序號 丨24曰申 U.S.C. § 言之，本 I 〇 過氧化異 物離析酚 步驟。較 基苯乙烯 係經導引 酚。取決 者，蒸倉留 ，可能還 [e，MO ) 物、烯烴 2 -和 3 -例如於雙 200536818 (2) ~ 酚-A的製造中所用的酚內是不宜者。 • MBF係某些應用例如雙酚-A，聚碳酸樹脂之一種前驅 物，的製造中所用酚的特別不宜之污染物。由於有類似的 揮發性，無法藉由分餾從酚分離出 MBF。美國專利第 5,064,507號與第4,857,151號描述一種有水的蒸餾法（也 稱作蒸氣汽提（steam stripping))以減少酌中之MBF。 不過，由於高能量成本且需要使用大型蒸f留塔，就資本投 φ 資與作業成本而言，此方法係昂貴者。美國專利第 5,4 14,154號描述使用強酸離子交換樹脂藉由轉換其成爲 較高沸點化合物以減少MBF含量。美國專利第5,4 14,154 號也說明藉由樹脂處理去除MBF的效用性會隨著溫度增 加而增加。 儘管強酸離子交換樹脂也藉由接觸從酚去除羰基化合 物，不過乙醯曱醇會與酚反應而產生更多MBF。美國專利 第5，414,154號提出在與樹脂接觸去除MBF之前，從酚去 -# 除乙醯甲醇（例如，藉由用胺處理）的必要性。 ^ 儘管有效，不過胺處理涉及使用隨後必需從酚流滌除 的昂貴藥劑。 美國專利第3,8 1 0,946號與第6,489,5 1 9號揭示對包 含乙醯甲醇的酚流使用酸或酸性樹脂去除乙醯甲醇之處理 。英國專利第0 8 6 5 67 7號揭示一種用於從酚流去除乙醯 甲醇的方法，其中係於有或無催化劑之下加熱酚流。不過 ’在所有這些專利中，係藉由乙醯甲醇與酚反應形成MB F ’隨後將MBF由酚流滌除而去除乙醯甲醇。 200536818 (3) ^ 歐洲專利第〇 004 1 68號與美國專利第4,8 5 7，151號 ~ 係揭示可從酚流去除乙醯甲醇的蒸餾方法。不過’此等方 法涉及使用資本密集之蒸餾裝置。 目前亟須一種藉由形成明顯量的額外MBF而對酚產 率沒有不良影響的有效、低成本從酚流去除乙醯甲醇的方 法。 【發明內容】 本發明提供從酚流去除乙醯甲醇的有效低成本的方法 〇 在本發明一具體實例中，一種用於從酚有效低成本地 去除乙醯甲醇的方法包括將含乙醯甲醇的酚流與一酸性樹 脂在約8 5 ^ C或更低的溫度下接觸以轉化乙醯甲醇成爲除 甲基苯并呋喃之外的較高沸點化合物。隨後蒸餾該酚流以 從較高沸點化合物分離出酚。 在本發明另一具體實例中，一種用於有效低成本從酚 去除乙醯甲醇的方法包括在大於約1 7 5。C的溫度下加熱酚 流以轉化乙醯甲醇成爲除甲基苯并呋喃之外的較高沸點化 合物。此可以於有或無添加鹼金屬氫氧化物之下進行。隨 後，蒸餾酚流以從較高沸點化合物分離出酚。 在本發明的這兩個具體實例中，都可以有效去除乙醯 甲醇而大部份的乙醯甲醇沒有與酚反應，因而本發明方法 可導致減低的MB F形成及改善的酚產率。 200536818 (4) ' 【實施方式】 * 業經發現者，可以用低成本從酚有效去除乙醯甲醇同 時使甲基苯并呋喃 （MBF)之形成減到最少。可去除乙醯 甲醇的處理包括對含乙醯甲醇的蒸餾酚用酸性樹脂於低溫 下處理或用少量苛性劑於高溫下處理。藉由此處理，粗製 酚中之乙醯甲醇先被轉化爲除MBF外之高沸點產物。然 後，可經由蒸餾從酚分離出此等高沸點產物。 Φ 乙醯甲醇的去除對隨後從粗製酚有效去除MB F具有 關鍵性。如所知者，在轉化MB F成爲可從酚分離出的產 物所用之高溫與酸性條件下，乙醯甲醇會與酚反應產生更 多的MB F。這種反應有雙重效果：減少酚回收率且使得從 產物去除MBF的效率更低。 在本發明一具體實例中，包含乙醯甲醇的蒸餾酚流係 與酸性樹脂在約85° C或更低的溫度下接觸以轉化乙醯甲 醇成爲除MBF之外的較高沸點化合物。酸性樹脂處理之 Φ 後，係藉由蒸餾從較高沸點化合物中分離出酚。處理時間 ^ 及溫度會基於要從粗製酚去除的乙醯甲醇之量而變異。處 理時間可從5分鐘變異至1小時。在一範例處理中，係藉 由與酸性樹脂在約8 5 ° C溫度下接觸約1 5分鐘而從粗製酚 流去除7 0 0 p p m的乙醯甲醇。在此例中，只有約1 2 °/。的乙 醯甲醇被轉化爲MB F。 較佳者該酸性樹脂係呈固定床形式，使酚流在其上通 過。酚流通過樹脂床的速率較佳者爲1至1 2床體積/小時 200536818 (5) 第1圖顯示出用A m b e 1· 1 y s t 3 6於8 3 Q C下處理酚樣品 • ，將乙醯甲醇由約2 2 5重量p p m快速減少至接近〇 p p ηι 。可以看到Μ B F的形成達到最少。如果是要將所有乙醯 甲醇都轉化爲MBF，則預期會有約400重量ppm的MBF 總濃度。反而，2-MBF與3-MBF的組合濃度只有約25重 墓ppm。弟2圖再次顯不包含約225 重量ρρπι乙釀甲醇 的粗製酚流用A m b e r 1 y s t 3 6於8 5。C下處理。再度地，乙 φ 醯甲醇含量極快速減少至接近〇 ppm，而MBF的形成也最 小。如在第2圖中可進一步看出者，延長在85。C的保持 時間不會導致MBF含量的增加。這表示藉由酸性樹脂處 理從乙醯甲醇生成的重產物在此溫度下係穩定的。 酸性樹脂處理後之蒸餾較佳者爲在減壓下實施的急驟 蒸餾（flash distillation )，以避免酸性處理期間形成 的高分子量物種斷裂所致Μ B F的形成。真空下急驟蒸餾 的使用具有額外的優點：排除先前技術方法中分離酚與乙 # 醯甲醇所用的昂貴蒸餾裝置。不過，應察覺者，可以使用 多種蒸餾法與本發明結合，只要小心避免酸性處理期間形 成的高分子量物種之分解即可。 請參考第3圖，其中闡示避免酸性樹脂處理期間形成 的重產物的分解之必要性。第3圖顯示高溫樹脂處理對於 已用酸性樹脂在8 5。C處理以轉化乙醯甲醇爲較高沸點化 合物而沒有先行去除較高沸點產物的酚流之影響。如可看 出者，高溫導致額外MBF的形成。這表示在低溫酸性樹 脂處理中形成的較高沸點化合物在酸性樹脂存在中的高溫 -8- 200536818 (6) 下會分解回到乙醯甲醇’且隨後與酚反應而形成Μ B F。這 - 不只造成酚損失，而且’如可看出者’也造成爲減少MBF 含量至接近〇重量ΡΡηι所需時間的明顯拉長，約爲13〇 分鐘。 第4圖闡不酸性樹脂處理形成的較高沸點化合物在高 溫酸性樹脂處理之前經由酚的急驟蒸餾以去除MB F之例 子。如在第4圖可以看出者，MBF含量沒有增加。此外， φ MBF含量在約10分鐘，而非130分鐘內減少至接近〇 ppm 〇 在本發明另一具體實例中，包含乙醯甲醇的蒸餾酚流 係在一密閉系統內於高溫下加熱以轉化乙醯甲醇成爲除 MB F之外的較高沸點化合物。該加熱處理可以在有或沒有 添加少量苛性劑之下進行。若該加熱處理係在沒有添加苛 性劑之下進行，則該酚流的pH應該高於2，較佳者高於 2 · 5。通常，此爲來自經中和的反應產物之蒸餾酚流所具 # PH値。較低的pH可能導致加添量的MBF。苛性劑較佳者 係以濃溶液形式添加，例如5 0重量％。再度者，係經由蒸 餾而從較高沸點化合物分離出酚。用於加熱處理的溫度爲 至少175至22 5。處理時間、溫度與苛性劑用量（若需要 時）會基於要從酚流去除的乙醯甲醇之量而變異。如圖5 所闡示者’在一範例處理中，係藉由在沒有加任何苛性劑 之下’於1 9 8。C加熱約4小時將1 0 3 6 ppm的乙醯甲醇加 少到低於1 0 p p m。於此例中，只有1 %的乙醯甲醇轉化成 爲MBF。如圖6中所闡示者，於用2 66 ppm的5〇%苛性劑 200536818 (7) 存在中，只在約2小時內就將1 〇 4 5 p p m的乙醒甲醇減少 到低於1 0 p p m。不過仍然有稍微較尚量（〜1 · 6 %)的乙酿甲 醇轉化爲Μ B F。應指出者，於高溫的有效率乙醯甲醇之去 除需要所處理酚流中有低水含量，例如以酚爲基準低於 1 . 5 %。較佳者，水含量係經減低到約〇 · 1重量％。減少有 機流，特別是酚，的水含量所用的各種方法皆爲技藝中所 知者。下面表1顯示出將乙醯甲醇從1 8 0 0減少之其他例 表1 藉由用添加的苛性劑之熱處理去除乙醯甲醇 1800 ppm乙醯甲 5 0%苛性劑濃度 醇減至1 0 p p m 溫度 260 ppm 525 ppm 1100 ppm 175° C >7小時 190° C 5小時 5小時 1 98° C 4.5小時 3.5小時 2.3小時* *於1.5 %水濃度2.75小時 在處理去除乙醯甲醇之後，即可從較高沸點化合物蒸 餾出酚，且可於高溫下通過酸性樹脂處理以去除MBF，如 美國專利第5,4 14,154號與第6,3 8 8,1 44 Β1號中所揭示者 ，兩者的全部內容皆以引用方式倂入本文。 -10- 200536818 (8) ^ 可從酚去除乙醯甲醇的本發明方法具有比使用蒸餾裝 - 置，例如，超分流管柱的先前技術方法及使用昂貴胺類的 先前技術方法更具成本效益之優點。此外，本發明方法具 有從要去除的乙醯甲醇產生比利用高濃度苛性劑或依賴用 酸性樹脂做多重高溫處理的先前技術方法更少MB F之優 點。 φ 【圖式簡單說明】 第1圖闡示藉由與酸性樹脂於83° C下反應以從酚流 去除乙醯甲醇。 第2圖闡示藉由與酸性樹脂於8 5。C下反應以從酚流 去除乙醯甲醇且靜置於85。C不會形成明顯量的MBF。 第3圖闡示當用酸性樹脂於8 5。C下處理過的酚流直 接與酸性樹脂於133 °C下接觸時所發生的MBF之形成。 第4圖闡示在將由乙醯甲醇經由用酸性樹脂低溫處理 φ 接著蒸餾而去除之後，藉由與酸性樹脂於1 3 4。C反應從酚 流有效去除Μ B F。 第5圖闡示經由在一密閉系統內於198°C下加熱以從 酚流有效去除乙醯甲醇。 弟6圖闡不經由在一密閉系統內於2 6 6 p p m的5 0。/〇的 苛性劑之存在中在1 98°C下加熱以從酚流有效去除乙醯甲 醇。 -11 -200536818 (1) IX. Reference to the related application of this invention This application is a follow-up application of application 10 / 915,723 filed on August 9, 2004. The application claims the serial number of the provisional patent application filed on March 3, 2004. 60/5 5 6,23 6 has priority under 35 · 1 19 (e). [Technical field to which the invention belongs] The present invention relates to the field of manufacturing high-purity phenol. A more specific invention relates to the removal of acetamethanol from phenol to achieve a desired high purity. [Prior Art] A method commonly used to make phenol involves oxidizing cumene to hydropropylbenzene, followed by acid-catalyzed decomposition into phenol and acetone. Neutralization of the acid catalyst from the reaction system followed by a series of distillation and separation of φ low-boiling components such as acetone, unreacted cumene and α-formyl (AMS) was first recovered from the crude product by distillation. Residual material is transferred to a phenol recovery column, in which phenol distilled from higher boiling impurities to recover acetone, cumene, and the distillation procedure used by AMS, in addition to the remaining amounts of acetone, cumene and AMS A small amount of impurities, such as mesityl oxid, acetamethanol (hydroxyacetone), and other aliphatic carbonyl compounds, acetophenone, cumene (cumy 1 P he η ο 1), and methylbenzene Benzofuran (MBF). In some applications, these impurities can be applied for in USC § 24, USC § In other words, this phenol peroxide foreign matter separation step. More basic styrene is guided phenol. Depending on, steam In the case of storage, [e, MO) compounds, olefins 2-and 3-may be unsuitable in the phenol used in the production of bis-200536818 (2) ~ phenol-A. • MBF is a particularly undesirable contaminant for phenols used in the manufacture of certain applications such as bisphenol-A, a precursor to polycarbonate resins. Due to similar volatility, MBF cannot be separated from phenol by fractional distillation. U.S. Patent Nos. 5,064,507 and 4,857,151 describe a water-based distillation method (also known as steam stripping) to reduce MBF. However, due to the high energy cost and the need to use a large distillation column, this method is expensive in terms of capital investment and operating costs. U.S. Patent No. 5,4,14,154 describes the use of strong acid ion exchange resins to reduce MBF content by converting them to higher boiling compounds. U.S. Patent No. 5,4,14,154 also shows that the effectiveness of MBF removal by resin treatment increases with temperature. Although strong acid ion-exchange resins also remove carbonyl compounds from phenol by contact, acetic alcohol reacts with phenol to produce more MBF. U.S. Patent No. 5,414,154 suggests the need to remove-# acetamethanol (for example, by treatment with an amine) from phenol before removing MBF by contact with the resin. ^ Although effective, amine treatment involves the use of expensive agents that must subsequently be removed from the phenol stream. U.S. Patent Nos. 3,8 1 0,946 and 6,489,5 1 9 disclose the use of acid or acid resins to remove acetamethanol from phenol streams containing acetamethanol. British Patent No. 0 8 6 5 67 7 discloses a method for removing acetamethanol from a phenol stream, wherein the phenol stream is heated with or without a catalyst. However, in all these patents, MBF is formed by the reaction of acetamethanol with phenol, and then MBF is removed from the phenol stream to remove acetamethanol. 200536818 (3) ^ European Patent No. 0 004 1 68 and U.S. Patent No. 4,8 5 7,151 ~ ~ Disclose a distillation method capable of removing acetamethanol from a phenol stream. However, these methods involve the use of capital-intensive distillation units. There is an urgent need for an effective, low cost method for removing acetamethanol from phenol streams by forming a significant amount of additional MBF without adversely affecting phenol yield. [Summary of the Invention] The present invention provides an effective and low-cost method for removing acetamethanol from a phenol stream. In a specific example of the present invention, a method for efficiently and cost-effectively removing acetamethanol from phenol includes acetamethanol The phenol stream is contacted with an acidic resin at a temperature of about 8 5 ^ C or lower to convert acetamethanol to higher boiling compounds other than methylbenzofuran. This phenol stream is then distilled to separate phenol from higher boiling compounds. In another embodiment of the present invention, a method for efficiently and cost-effectively removing acetamethanol from phenol comprises at a temperature of greater than about 175. The phenol stream is heated at a temperature of C to convert acetamethanol to a higher boiling point compound other than methylbenzofuran. This can be done with or without the addition of an alkali metal hydroxide. Subsequently, the phenol stream is distilled to separate phenol from the higher boiling compounds. In these two specific examples of the present invention, both acetamethanol can be effectively removed and most of the acetamethanol is not reacted with phenol, so the method of the present invention can lead to reduced MB F formation and improved phenol yield. 200536818 (4) '[Embodiment] * It has been discovered by industry that can efficiently remove acetamethanol from phenol at a low cost while minimizing the formation of methylbenzofuran (MBF). Acetyl-methanol-removable treatments include distilling phenols containing acetamidine with acidic resins at low temperatures or with a small amount of caustic at high temperatures. By this treatment, the acetamethanol in the crude phenol is first converted into a high-boiling product other than MBF. These high boiling products can then be separated from the phenol by distillation. Φ Removal of acetamethanol is critical for the subsequent effective removal of MB F from crude phenol. As is known, under the high temperature and acidic conditions used to convert MB F into a product that can be separated from phenol, acetamethanol will react with phenol to produce more MB F. This reaction has a dual effect: reducing phenol recovery and making MBF removal from the product less efficient. In a specific example of the present invention, a distilled phenol stream containing acetamethanol is contacted with an acidic resin at a temperature of about 85 ° C or lower to convert acetamethanol to a higher boiling compound other than MBF. After treatment with acid resin, phenol is separated from higher boiling compounds by distillation. The processing time ^ and temperature will vary based on the amount of acetamethanol to be removed from the crude phenol. Processing time can vary from 5 minutes to 1 hour. In an exemplary process, ethmethanol is removed from the crude phenol stream by contacting an acidic resin at a temperature of about 85 ° C for about 15 minutes. In this example, it is only about 12 ° /. Methyl acetate was converted to MB F. Preferably, the acidic resin is in the form of a fixed bed through which phenol flows. The rate of phenol flow through the resin bed is preferably 1 to 12 bed volume / hour 200536818 (5) Figure 1 shows the treatment of phenol samples with A mbe 1 · 1 yst 3 6 at 8 3 QC. Methanol rapidly decreased from about 2 2 5 ppm by weight to nearly 0 pp ηι. It can be seen that the formation of MF is minimized. If all acetamethanol is to be converted to MBF, a total MBF concentration of about 400 ppm by weight is expected. Instead, the combined concentration of 2-MBF and 3-MBF is only about 25 ppm. Figure 2 shows again that the crude phenol stream that does not contain about 225 weight ρρπι ethyl methanol is used for Ambe r 1 y s t 3 6 to 8 5. C was processed. Once again, the methanol content of ethyl φ 醯 decreased very quickly to close to 0 ppm, and the formation of MBF was also minimal. As can be seen further in Figure 2, the extension is 85. The holding time of C does not cause an increase in MBF content. This indicates that the treatment of heavy products from acetic acid methanol by acidic resin is stable at this temperature. The distillation after the acidic resin treatment is preferably a flash distillation performed under reduced pressure to avoid the formation of MF by cleavage of high molecular weight species formed during the acidic treatment. The use of flash distillation under vacuum has the added advantage of eliminating the expensive distillation apparatus used in the prior art methods for separating phenol from ethyl #fluorene methanol. However, it should be observed that a variety of distillation methods can be used in combination with the present invention, as long as care is taken to avoid decomposition of high molecular weight species formed during the acid treatment. Refer to Figure 3, which illustrates the need to avoid decomposition of heavy products formed during acid resin treatment. Figure 3 shows the high temperature resin treatment for the used acid resin at 8 5. C treatment converts acetamethanol to higher boiling compounds without the effect of removing the phenol stream of higher boiling products first. As can be seen, high temperatures lead to the formation of additional MBF. This means that the higher boiling compounds formed in the treatment of low-temperature acidic resins will decompose back to acetamethanol 'at the high temperature in the presence of acidic resins -8-200536818 (6) and then react with phenol to form MBF. This-not only causes a loss of phenol, but 'as can be seen' also causes a noticeable lengthening of the time required to reduce the MBF content to close to 0 weight PPn, approximately 130 minutes. Figure 4 illustrates an example of the higher boiling point compounds formed by the treatment of non-acidic resins by the rapid distillation of phenol to remove MB F before the treatment of high-temperature acidic resins. As can be seen in Figure 4, the MBF content did not increase. In addition, the φ MBF content is reduced to approximately 0 ppm in about 10 minutes instead of 130 minutes. In another embodiment of the present invention, the distilled phenol stream containing acetamethanol is heated at a high temperature in a closed system to convert Acetyl methanol becomes a higher boiling compound other than MB F. This heat treatment may be performed with or without the addition of a small amount of a caustic. If the heat treatment is performed without the addition of a caustic agent, the pH of the phenol stream should be higher than 2, and preferably higher than 2.5. Typically, this is the #PH 値 of the distilled phenol stream from the neutralized reaction product. Lower pH may result in added MBF. The caustic is preferably added in the form of a concentrated solution, such as 50% by weight. Again, phenol is separated from higher boiling compounds by distillation. The temperature for the heat treatment is at least 175 to 22 5. Processing time, temperature, and caustic dosage (if required) will vary based on the amount of acetamethanol to be removed from the phenol stream. As illustrated in Figure 5, 'in an exemplary process, by adding no caustic agent' at 198. C was heated for about 4 hours to reduce 10 6 ppm of acetamethanol to less than 10 p p m. In this example, only 1% of acetamethanol was converted to MBF. As illustrated in FIG. 6, in the presence of 2 66 ppm of 50% caustic 200536818 (7), 10 5 ppm of acetone methanol was reduced to less than 10 in about 2 hours. ppm. However, there is still a slightly higher amount (~ 1.6%) of ethyl methyl alcohol converted to MBF. It should be noted that the removal of efficient acetamethanol at high temperature requires a low water content in the phenol stream to be treated, for example, less than 1.5% based on phenol. Preferably, the water content is reduced to about 0.1% by weight. Various methods for reducing the water content of organic flow, especially phenol, are known in the art. Table 1 below shows other examples of reducing acetamethanol from 18,000. Table 1 Removal of acetamethanol by heat treatment with added caustic agent 1800 ppm acetamidine 50% caustic concentration alcohol reduced to 10 ppm Temperature 260 ppm 525 ppm 1100 ppm 175 ° C > 7 hours 190 ° C 5 hours 5 hours 1 98 ° C 4.5 hours 3.5 hours 2.3 hours * * At 1.5% water concentration 2.75 hours After the removal of acetamethanol, you can Phenol is distilled from higher boiling compounds and can be treated with acidic resins at high temperatures to remove MBF, as disclosed in U.S. Patent Nos. 5,4 14,154 and 6,3 8 8,1 44 B1, both The entire contents are incorporated herein by reference. -10- 200536818 (8) ^ The method of the present invention capable of removing acetamethanol from phenol is more cost-effective than the prior art method using a distillation apparatus such as a super splitter column and the prior art method using expensive amines Advantages. In addition, the method of the present invention has the advantage of producing less MB F from acetamethanol to be removed than prior art methods that use high concentrations of caustic or rely on multiple high temperature treatments with acidic resins. φ [Schematic description] Figure 1 illustrates the removal of acetmethanol from a phenol stream by reaction with an acidic resin at 83 ° C. Figure 2 illustrates the use of acidic resins on 8 5. Reaction at C to remove acetamethanol from the phenol stream and stand at 85. C does not form a significant amount of MBF. Fig. 3 illustrates the use of acidic resins when scoring 5 to 5. The formation of MBF occurred when the phenol stream treated at C was in direct contact with the acidic resin at 133 ° C. Fig. 4 illustrates the removal of acetic acid methanol by low temperature treatment of φ with an acidic resin followed by distillation, followed by the reaction with the acidic resin at 1 3 4. The C reaction effectively removes MBF from the phenol stream. Figure 5 illustrates the effective removal of acetamethanol from a phenol stream by heating at 198 ° C in a closed system. Figure 6 illustrates that 50 does not pass through 2 6 6 p p m in a closed system. / 0 in the presence of a caustic agent heated at 1 98 ° C to effectively remove acetomethyl alcohol from the phenol stream. -11-