Catalytic Cyclocondensation of Acetone to Isophorone
1l1dian Joumal of Chemistry VoL )8B, January 1999, pp 24 - 28
Catalytic Cyclocondensation of acetone to isophorone
K V Ramanamurty & G S Salvapati * Indi an Institute of Chemical Techn ology, Coal and Gas Tec hno logy Di vision Hyderabad 500007, Indi a
Received 12 March 1997; accepted (revised ) 13 Feb ntary 1998
Cyclocondensation of acetone in vo lves aldol co ndensati on leadin g initiall y to the primary condensation prod ucts (PCP), di acetone alcohol and mesityl ox ide, whi ch again react with acetone to form phorone, isop horone, mesitylene. etc. Relative selectiv ities of chromi a, y-alumin a, mag nesia and calci um ox id e catalys ts have been stud ied in a flow reac tor at 360-520 'c. Alu mi na and magnesia are fo und to favo ur isop horone fo rmation at 360 'c with 45 % selectivi ty but the selectivity steeply fa ll s with the in crease in temperatu re to 520 'c due to rise in decomposition prod ucts.' Primary condensation products are formed more wi th magnesia; selec ti vity to mes it ylene is mo re wi th CaO (-66% at 40U-480 'C) and Cr20 ] (50-55% at 480-520 ' C).
Cyclocondensation of acetone proceeds initiall y by aldol (24 g) was packed in the iso th er-mal region of th e reactor. condensation of acetone to form diacetone alcohol, whi ch Nitrugen' gas was passed at th e rate of 180 mLlhr through on rapid dehydrati on gives mesityl ox ide. The sequence of the s:istem during the heating peri od to purge the system reactions that follow thereafter give ri se to a compl ex free of air and also during the experimental ru n to maintain mixture of products due to competiti ve self-condensati on uniform now of reaction products. Acetone (SOH reagent and cross condensati on between different ketones that are grade) was fed at the rate of 0. 5mLlmin from th e top of the fo rmed in the reacti on as well as by condensati on of acetone reactor by means of a mi cro feed pump. The system was with ketones. Main products fo rmed in these reactions are fo und to attain a steady state aft er 30 min . of process isophorone, mesitylene, phorone, 3,5-xyl enol, m-cresol and period. xylenes. Schemes for formati on of th ese products are l Catalysts (a) Y -alumina: Alumi nium scrap (AI 99.9%, Fe described in detail in our earli er publicati ons .] However, a 0. 1% max) was di ssolved in 5N HCI and ammonia soluti on general scheme is give n in Figure 1. ( 17 %) added to it dropwise under constant sti rring to bring The two primary intermedi ate condensati on products pH to 8. The aluminium hydroxide ge l was filtered, dried at (di acetone alcohol and mesityl oxide) and other pro-ducts 110 'c and calcined at 550 'c for 24 hr. The final materi al find many industri al applicati ons: Isophorone is a well was found to contain a chl oride content of 166 ppm (as kn own industri al solve nt for epoxy and phenoli c res inso. It determined by Mohrs method). Pellets of 4mm x 4mm size is also used for the preparati on of 3,5-xylenol whi ch find s we re prepared. applicati on in the manufact.ure of formaldehyde res ins6 and 7 formul ati ons with ant ibac- teria l and fun gicidal properti es . (b) Magnesia: Magnesi um carbonate (Sarabhai Chemi -cals, Other intermediates also find industri al applicati ons, for Baroda, India) was calcined at 600 'c fo r 6 hr to get 8 example di acetone alcohol in hydrauli c nuids , its aqueous magnestum ox ide. Pell ets of 4mm x 4mm size were solution (25 %) as bacteri cide to staphylococciY and mesit yl prepared. oxide as solve nt for phenol formaldehyde resinslo and PVC (c) CalciUlm oxide: Calcium oxide was prepared by composition II . calcining calcium carbonate (BOH reagent grade) at 600 'c In th e present study, th e catalys ts CaO, MgO, AI20 J and fo r 6 hr. Pell ets of 4mm x 4mm size we re prepared. Cr20] have been evaluated at 360-560 ·C and LHSV 1.0 for th eir selecti vit y in direct conve rsion of acetone to (d) Chmmium oxide: Chromium oxide ge l was isoph orone. prec ipitated from chromiu m sul phate (Apex Chemicals, Materials and Methods: Bombay, Indi a, reagent grade) by ad ding ammoni a solut ion ( 17 %) dropwise under constant stirring. The result ing ge l Apparatus: The experimental unit is essent ia ll y th e same as was fi It ered, dried at I 10 "c, and calcined at 500 "c fo r 4 hr. desc ri bed in our earli er paper I. The reactor consists of a Pel lets of 4mm x 4mm size we re prepared. ve rti cal tuhul ar r:.., ac tor (2 2 mm i.d. and 25mm o.d.) heatrd hy an elec trical furn ace. The catalys t (4 mm x 4mm pell ets) Phys ical propert ies of the catalysts arc given in Table L RAMANAMURTY et al. : CYCLOCONDENSAnON OF ACETONE TO ISOPHORONE 25
(~ I +(H3-(&0 (H'3 .(0.(H _ 3 Acetone
I so x ylitone s
Figure 1-Scheme of formation of reaction products in the cyc1ocondensation of acetone.
0.98 respectively. Gaseous products collected during these Analysis. Liquid products collected during the experi-ments experiments at 480-520 °c accounted for -4% based on the were analysed using 115" X 8' column of Ov-17 as feed, and the coke formation was -3%, the rest was liquid chromosorb W with flame ionization detector (FlD) by products. Analysis of the gas samples showed the presence programming the oven temperature at 5 °C/min between 60 of ethylene, propylene, isobutene, CO and CO which are and 180 °C, acetone content in the product was analysed by 2 formed by the decomposition of mesitylene, diacetone internal standard method using n-propanol as standard over alcohol and acetone respectively. 15% Carbo wax -20M on Chromo sorb W at 60 °C. Analysis Results and Discussion: of the product mixtures was done by internal normalisation method by taking diacetone alcohol as standard. The Conversion of acetone to isophorone is visualized along relative weight response factors of mesityl oxide, phorone, the reaction path: acetone ~ diacetone alcohol ~ mesityl iso-phorone and mesitylene were to be 1.08, 0.82, 0.79 and oxide ~ isophorone l.2·12. Thus, the reactions involved are aldol condensation to diacetone alcohol, its dehydration to mesityl oxide and cyclization reaction leading to isophorone Table I - Physical properties of catalysts the formation of (as shown in Figure 1). Maj or side Property Catalyst reactions are decomposition reactions of mesityl oxide or Cr203 y-AI 2O, MgO Cao diacetone alcohol giving isobutene, which is cyc1ized to 3 Surface Area (m2/g) 80 160 120 60 mesitylene . Bulk density (glmL) 0.61 0.75 0.83 0.89 Alumina catalyst was tried at low temperatures (60- 100 Mean pore radius (A) 40.0 45 .5 38.0 42.5 0c) to give mainly diacetone alcohol 13. At 300-500 °c and Cumulative pore volume 0.35 0.48 0.31 0.52 under a pressure of 200 atmospheres, the main product was (mUg at STP) I4 15 mesitylene . , the formation of which was considerably 26 INDIAN J CHEM, SEC. B, JANUARY 1999
hig her than in the case of H2S04 as catalyst I S In the present work , formation of isophorone was fav oured at 300-360 ·C 100 (- II %) but thereafter it decreased due to the mu lt iplicity of products (Figure 2). Mesitylene formation was also more 80 (2 1%) at 480-520 .c. Magnesia is well known to promote aldol condensa-tion of acetone but its efficacy in the 60 cycl izati on reac-ti on leading to isophorone is not well 0~ establi shed 17.18.19 ItO
Mag nesia was found to be more active at 440-520 ·C 20 (Figure 3) to give primary the condensation products MgO (mainl y mesit yl oxide) ( 19%) rather than isophorone. CI However, formati on of 7% mesity lene with 27 % selecti -v it y 360 1.00 1.1.0 1.60 at 520 ·C and a max imum of 6% isophorone at 440 ·C (Figure 4) TEMPERATU RE " C
Figure 4--Erfect of temperature on selecti vit y to mesit ylene. 1.0
30 ~ 50 •-J 20 o • ~ 10 40
~ 30 300 TE MPERATURP C 20
f>..c.---o.---.:~~.. A 1203 10 t. ( 00 H gl) Figure 2--Effect of temperatu re on produci composi ti on with - Cr203 AI o 20 , catalyst. 360 400 1. 40 480 520 TEMP ERA TUR E • C
Figure 5-EITcc t of temperature on selecti vi ty tl) isophorone . .-. PCP
~ Mesitylene renders it less selec ti ve to isoflhorone. Both alumina and lr--A Isop hor one Magnes ia have hett er se lec tivi ty compared to isophorone at low tem peratures (- 360 "C) than oth er catalys ts , but there was a steep fall in se lectivit y with the increase in reaction 20 temperature to 520 'c (Figure 5) due to the rise in the amount of decompositi on products. 16 Chro mi a is a we ll kn own catal ys t in the Jromatiza ti on of hydrocarhons. But , it is re port ed to favour mesitylene 12 formation at 350-360 'C20 In our studies, thi s catalys t was .~ -J tri ed at 350-560 ·C for 1.0 hr . The amount of isophorone 0 %: fo rmed was found to be low Imax imum of 3. 3% at 380 C I. (Figure 6)1 and mes it ylcne was formed in higher amounts ( 16% at 400-440 "C) with 660/.- se lecti vity (Figure 4). 0 1.00 1.1.0 Calcium oxide was reported to give mainl y the diacdon" TE MP'ERA TUR PC alcohol at 0-30 "Cl l. In our studi es, CaO W a S foun d to give ve ry low amounts of isophorone givi ng a max imum yield of 2. 6% at 480 ·C (Figure 7). This catalys t is found to Figure 3-Effeci of temperalllre on product composi ti on with promote mes it ylene formation ( 12% at 520-560 .C) with MgO catalyst. 50% selectivity (Figure 4). RAMANAMURTY et al. : CYCLOCONDENSATION OF ACETONE TO [SOPHORONE 27
.-- PCP the formalion of primary condensation products. Though ~ Muitylene AlzO) and MgO gave more primary condensat(on products 16 f,.....-..6. Isophorone (PCP), dehydrocyclization step is nol effective, Relative a---o 3,5 -Xylenol selectivity in the formalion of primary condensation produclS 12 is MgO>r-AlzO:vCaO> Cr20 ). With y-A1z0 ) , decomposition reaction was promo-ted al 380-520 ·C, giving 15% mesitylene in ';;t 8 the produci and consequenlly the formation of isophorone ....Jo X • • drasti -cally decreased (10 2% ) with the ri se in temperature 4 • 10 520 °C. With M gO , though primary condensation pro ducts formation was more, dehydrocyclizati on was not o Lf,;~*~~=:L-400 440 480 520 560 effected resulting in low yield of isophorone. Wilh CaO and TEMPERATURE • C Cr20 " the decomposition of primary condensation prod'ucts was promoted causing higher selectivity to mesitylene.
Hence, it may be concluded Ihat parall e l reac ti ons Figure 6-Effect of temperature on prod uct co mposition wi th leading to mesitylene were affecting Ihe selectivity to
Crl 0.1 catalyst isophorone for the catalysts AI 20 ), CrzO), CaO and M gO. C r20.1 and CaO favour mesitylene formation whereas wi th M gO primary condensation producls were formed more.
With A1 10 1. the reacti on is more complex leading to multiplic it y of products. In order to reduce the undesirable side reacti ons involvin g decomposition of pri mary 11 condensat ion products, the catalyst has been mod ified by neutra li zin g the acid ic sites (eg. addition o f K 0 ) and the 9 2 data will form part of ensuing paper.
~ 7 o Acknowledgement The authors thank Dr K V Raghavan, Director, Indian In stitute of Chemi cal Techno logy, Hyderabad for glViJ1g 3 permi ssion to publ ish this paper.
References Sa lvapali G S & Janardanarao M, J Scielll In d Res, 42, 1983, TEHPERATURP C 261. 2 Salvapali G S, Ramanam url y K V & lanard anarao M,l Mol Cawl, 54, 1989,9. Figure 7- Elfcct or Tcmperature on prndUl:1 composition with 3 Salv apali G S, Ramanamurl y K V & Janard anarao M, App/ CaO catalys t. Calul, 48, 1989.223. 4 Sev e~ lr i J, DOllb le Liusioll , 97, 1963.61; Chem Abstr, 66, 1967, 66798. 5 Kohl (Jr) C F, US Pal 2, 686. 739 (to Dow Corning Corp), 17 60 Au gust 1954; Chem Abslr, 48, 1954, 14295. 6 Ju enger H & Weisenfclps F, Fr Demande 2. 026, 678 (To ~ Dynami t Nobel A G) , 23 OClober 1970; Chem Abstr, 75. ...J 40 1'19 0 o 1971. 6857. :z: 20 7 Noeslor H G. Schnegclberger H & Hellinge r H, Ger Pal, I . 24R , 040 (tu Hcn kcl and Cie GmbH), 28 November 1968 ; OL-_"'::::::"_.l....-_.l....---''--_L-._ Chem A/wr. 72 . 1970. 625 2. 360 400 8 Rcnaull L, Fr Pm. 872 , 936. 23 June 1946; chem Abstr, 43, TEHPERATURE °C 1949, 479 1. 9 Ed el inaj J & Wolrran E. Am Univ Sci Budapesl Rolando /:'O{I'OS Nori\'(l/ac. Sen Chim , II , 1969, 125 ; Chem Abstr, Figure X-Erkcl or temperatu re un ,Ketone conversion. 73. 1970.1 10]69. 10 Fr Pm, 9!l2. 926 (to Societe' anon des manufactures dc, Acetone convcrsion In gencral was i"ound to increase wi th glaccs ct products C himiques de Saint Gobain, Chauny increase in te mperature with th e stu died catalysts and the and Circy) I X June 1951 : Ch(>l ll Abslr, 49, 1955, 4332. maximum CO il version was not more than 45 ch ror thcse II Johannes P C M. Nelh P UI , 7, 11 3. 138, 27 March 1973; catalysts (Figure 8 ). Acetone conversion is an indication o i" Chelll Ahstr. 79, 1973,67649. 28 INDIAN J CHEM , SEC. B, JANUARY 1999
12 Oi Cosimo J I, Oiez V K & Apesteguia C R, Appl Catat 17 Tanabe S, Baumann W & Thomke K, J Mol Catal, 69, 1991, A Gen, 1996, 149. 149. 13 Seligman R B, US Pat, 2, 879, 298, (to Phillip Morris 18 Tanabe K, Zhang G & Halton H, Appi Catai, 48,1989,63. Inc), 24 March 1959; Chern Abstr, 53,1959, 140008. 19 Lippert S, Baumann W & Thomke K, J Mol Catal, 69, 1991, 14 Tanabe K, Misono M, Ono Y & Hattori H, Stud Surf Sci 199. Catal, 51,1989, 327. 20 Fuju R, J Chern Soc Japan Pure Ch lErn Sect, 69, 1948, 131 ; 15 Reichle W T, J Catal, 63, 1980,295. Chern Abstr, 46, 1952,4474. 16 Ipatiev I V & Petrod A 0, Berdt Chern Ges, 59B, 1926, 2035. 21 Du Pont G & Menut M L, Bull Soc Chim, 6, 1939, 1215 .