Journ al of Scientifi c & Industri al Research Vol. 59, May 2000, pp 339-349 New Dimensions on Value Added Aldol Chemicals of Acetone K V Ramanamurty and G S Salvapati * Coal Division, Indi an In stitut e of Chemical Technology, Hyderabad 500007, India Aldol co nd ensati on of acetone provides a class of va lu e added chemicals: O'. , ~-un sa tur a t ed ketones and phenols. O'.,~­ Unsaturated ket ones are formcd by va ri ous cross co ndensati on and Mi chael reacti ons of ald ol products with acetonc or betwccn themse lves and phenol s are formed by either condensation of acetone with meth anol or ~-k e t o-a l co h o l or iso propanaldehyde or by di enone-phenol rcarrangement of O'. , ~-un sa turated ketone such as isophorone or by alk ylati on of iso ph orone wi th mcthano l. These proccsses are hi ghl y eco-fri endly and economi ca ll y viab le and are also ve ry selecti ve. All th e products can be separated and recovered by di still ati on and opti onall y, a more va lu able ketone iso ph orone ca n be obtained frec of other products by selecti ve ly co nverting them bac k to th e startin g materi al acc tone, thu s abso lutely requiring no diluent treatment. All thesc processes highli ght many new dimensions in th e production and emergin g trends in the unconventi onal utility in wide range of industries ex tending to pharmaceutical , food and vege tab le and aillied industries. Introduction ketones and phenols. Acetone is a cheaper raw mate ri al Acetone serves as an important industrial intenne­ and the processes for producing these compounds are diate leading to numerous chemicals, thus making it a hi ghly selective compared to the established industri al frontline raw material in many industries. There are many processes and it is abundantly available in India. HOCL reviews on acetone-based chemicals; it is not the inten­ produces 24,000 MT while Herdillia has a capacity of tion of this paper to add to this line. In recent years, ac­ 18 ,000 MT mostly by oxidation of cumene, NOCIL makes 14,000 MT from isopropyl alcohol I. Regarding etone is gaining significance as the starting material for the conventional end use pattern, 60% of the total de­ making selectively a,~-unsaturated ketones, wherein the mand is accounted by DAA, MIBK and methyl meth­ aldol products formed from acetone (Chart I) undergo acrylate. In this direction, the future production and end various cross condensation and Michael reactions with use potential of aldol products of acetone have been hi gh­ acetone or between themselves, leading to a variety of lighted. products and the production line extends to dimethyl­ and trimethyl phenol s by ecofriendly processes (water a.,~-Unsaturated Ketones from Acetone is the only byproduct) (Chart 2). These chemicals find many industrial applications and, in fact, the primary Auto-condensation of acetone proceeds by ald ol condensation product, 4-hydroxy-4-methyl-2-pentanone condensation which can be catalysed by acids as we ll as (diacetone alcohol, DAA) exhibits some wondeIi'u I prop­ bases. A large number of products (Chart I) are formed et1ies and it may be tenned as "viagra" to elephants. Thus, through either competitive paths at the addition-dehy­ the aim of this paper is to reveal new dimensions of these dration stage of diacetone alcohol itself or with the un­ aldol products of acetone in many areas in term s of th e used reactant, acetone. The major products in the reac­ versati Iity of the process, selectivity, ecofri endl i ness, tion are: diacetone alcohol , mesityl oxide, phorone, mesi­ absolutely requiring no efflu ent treatment and als o wide tylene, triacetone dialcohol , isophorone and isoxylitones range of industrial applications extending their utility in which have significant market pote ntiaj2 - I ~ (Table I). A pharmaceutical, food, vegetable and allied industri es in detailed di scussion on the reaction pathways of forma­ recent years. tion of these products has been reported earl ier"()ll. The basic raw material is acetone and under mild Though multiplicity of products arise in the product, re­ process conditions, the process is very viable for th e pro­ action can be optimised for the desired product through duction of two classes of compounds, a,~-unsaturated proper choice of process conditions (temperature, pres­ sure and catalyst) . Author for correspondence 340 J SCI IND RES VOL S9 MAY 2000 Chart 1 Reaction pathways of formation of aldol products from acetone 1 Fonnation of Diacetone alcohol by aldol condensation of Acetone 000 2CH - C - CH -- (CH3}2C - CH - C- CH 3 " 3 ""2 3 2 Formation of Mesityl oxide by dehydration of Diacetone alcohol OH 0 0 CI " - H20 " (CH3}2 - CH2- C - CH3 --- (CH3}2C = CH - C - CH 3 3 Formation of Triacetone dialcoho! by aldo! condensation of Diacetone alcohol with Acetone o OH 0 " OH 0 OH I II + CH3 - C - CH3 I " I (CH }2 C - CH - C - CH .. (CH3)2C - CH - C - CH - C(CH }2 3 2 3 2 2 3 4 Fonnation of Phorone by dehydration of Triacetone Dislcohol 5 Fonnation of Phorone by aldol condensation of Mesltyl oxide with Acetone 6 Fonnation of Isophorone by 1,S-Michael cydization of Phorone o c (CH3l,C=CH-tCH=C(CH3)2 - H3 D H3C CH3 7 Fonnation of Mesitylene from Mesityl oxide and Acetone by aldol condensation and 1,S-internal cydization reaction Contd ..... RAMANAMURTY & SALVAPATI : VALUE ADDED ALDOL CHEM ICALS OF ACETONE 34 1 Chart 1-Contd 8 Formation of Semiphorone by dehydration of triacetone dialcohol OH 0 OH OH 0 I II I I II C (CH 3)2 - CH 2 - C - CH2- C(CH 3) - (CH3)2C - CH 2 - C - CH =C(CH 3)2 9 Formation of Semiphorone by hydration of Phorone 0000 II I II C (CH3)2 =CH - C - CH = C(CH3)2 + H20 - (H3C}2C -CH2- C - CH = C(CH 3)2 10 Formation of t..ifetralone by reaction of Isophorone with Mesityl oxide o HC A I C ~ 3 ~ + (CH3 )2 =CH-C-CH3 _ H3C CH 3 o 11 Formation of lsoxylitones by aldol condensation of lsophorone with Acetone 12 Formation of Isoxylitones by self,condensation of MesItyt oxide 13 Formation of 2,2,6,6,-Tetramethyl pyron-4-one by cydization of Semiphorone o (C~3)2r CH,- g. CH = C (CH3l:. - . H3cDCH, H3C 0 CH 3 14 Formation of 3,3,6,8-Tetramethyl tetralone by reaction of lsophorone with Mesityl oxide o C~ 0 H C + (CH3)2C=CH.tCH, 3~A C H3C CH3 H3 342 J SC I INO RES VOL S9 MAY 2000 Chart 2 Reaction paths of formation of phenols from acetone Formation of m-Cresol by condensation of Methanol with Acetone CH30H --- CH20 + H20 CH3·CO.CH3+ CH20 - CH3·CO.CH2·CHzOH CH3·CO.CHz·CH20H --- CH3·CO.CH2·CHO + H2 OH CH ·CO.CH ·CHO + CH ·CO.CH --- + 0 3 2 3 3 ~ 2H2 CH3 2 Fonnation of 3,5-Xylenol by condensation of ethanol with Acetone CH3·CH2 0H - CH3·CHO + H2 CH ·CHO CH ·CO.CH - CH ·CO.CH ·CHOH.CH 3 + 3 3 3 2 3 CH3·CO.CH2·CHOH.CH3 - CH3·CO.CH2·CO.CH3 + H2 OH + + 0 CH,.CO.CH2CO.CH, CH,COCH, -~ 2H 2 C H3 CH 3 3 Fonnation of 3,5-Xylenol by die none-phenol rearrangement of lsophorone (fanned from Acetone) 0 H,cD + 2H20 C H3 CH 3 o 0 H,cD C H3 CH 3 H3Cn CH 3 4 Fonnatlon of 2,3,5-Trimethyl phenol and m~resol by disproportionation of 3,5-Xylenol OH OH OH H~C ~ CH' ~ CH' + H,che::: 5 Fonnation of 2,3,5-Trimethyl phenol by alkylation of lsophorone with Methanol CH H,C + CH,OH -.. - , + CH, + H0 ~ k 2 H3C~CH3 H3C CH3 6 Fonnation of 2,3- and 2,5-xyIenols by decomposition of 2,3,5-Trimethyl phenol CH 2 + , + CH, ~ CH' ~(H' iir 2 H3C ~ CH3 CH 3 H3C RAMANAMURTY & SALVAPATI : VAL UE ADD ED ALDOL CHEMI CA LS OF ACETO E 343 Tab le I - Industri al app li ca ti ons of aldol chemicals from acetone SI No. Produ ct Indus tri al Applications Di acetone alcohol Bacteri cidal to S t a phyloco cc i ~ In bra kc fluid s 1 In polyv in ylacetate. styrene-butadiene latex compositions· In printing ink s without envi ronm ent al haza rd s' In corrosion in hibiting paints, leuco vat dyes compositions" 2 Mes it yl ox ide As so lvent and plas ti ciser in PVC formul ati ons7 In paint remover formulations and in remov ing resins or chl orin ated rubber coatin ti ngs' Perfume il nd fra grance co mpositionsY As solvent of' polymer in phenoli c resi ns, polys tryrenes, epoxy resins and pol yisoeyanates" l 3 Isophoron e In ph enol-form aldehyde and phenol furural res in s" In PVC compositions, swelling agent s'l Indu strial solven t for epoxy and phenoli c resins" Chl ori nat ed isophorone as fun gicide'· In making 3,5-xylenol and 2,3,5-trimeth yl ph enol'; 4 Mes it ylene In offse t press for cleanin g rubber bl ank et'" In di sinfecting and clean in g pastes' 7 5 Phorone As stimul an t for stem and leaf growth s in beans " Fo r dec reasin g th e storage breakdown of appl es'" The formation of di acetone alcohol is equilibrium D e hydrati o n of triaceto ne dialcoho l y ie lds controlled so that reverse reacti on to acetone or dehy­ semiphorone.