REACTIONS OF HUGH.J. HAGEMEYER, JR. Tennessee Eastman Corporation, Kingsport, Tenn.

Ketene and carbonyl compounds can react to form either HC-CH H:-~~CHCH.C=OL-OJ acetates or p-lactones and products thereof, depend- He b-CHO $ CH2=C=O --+ H ing on the choice of catalyst and reaction conditions. KOAc \/ ---t Enol acetates are formed by reaction of enolizable car- '6 60°C. 0 bonyl compounds-that is, a carbonyl compound con- taining at least one available hydrogen atom on a carbon CH-CH atom adjacent to the -with ketene in the presence of acid esterification catalysts. Acetylsulfo- acetic acid is a preferred enol acetylation catalyst and temperatures in the range 50" to 90" C. are usually em- CeHsCHO + CHa=C=O CaH6CHCHZC=O + ployed. Ketene and carbonyl compounds react to form KOAC -0.J p-lactones and products thereof in the presence of suitable 60" C. condensation catalysts. The optimum conditions, cata- CsHsCH=CHs + COa lysts, and catalyst concentrations vary for individual carbonyl comqounds. The choice of the catalyst and Hurd used anhydrous potassium acetate as a catalyst and in catalyst concentration should be such that maximum addition to the decarboxylation products he isolated furacrylic rate of reaction is obtained with a minimum formation of acid and cinnamic acid which probably resulted from the depoly- . If 0-lactones or decarboxylation products merization of linear polyesters of the corresponding p-lactones thereof are the desired compounds, the reaction should upon distillation. be conducted at low temperatures, 0' to 10" C., to mini- Staudinger in 1911 (16) reported diphenylacetylation of the mize the linear polymerization of the p-lactone. Where enol of acetophenone with diphenylketene. Vinyl diphenylace- the unsaturated acid is the desired product, the reaction tate was also prepared by the reaction of diphenylketene with is conducted at 40" to 60" C., to ensure the gradual forma- acetaldehyde. The enol were identified by hydrolysis and tion of the linear polyester of the p-lactone, which is then isolation of diphenylacetic acid. Gwynn and Degering (4) in depolymerized by distillation. 1942 discovered that enol acetylation with ketene was accom- plished in good yields by using acid esterification catalysts. Ace- tone and ketene reacted in the presence of sulfuric acid catalyst to form isopropenyl acetate. ETENE, the inner anhydride of acetic acid,ismanufactured K by the pyrolysis of acetic acid and . Commer- CHsCOCHa CH-C(OH)CHs + CH2=C=O/EI2SOd + cially it is used principally in the production of acetic anhydride CHFC(CH~)OCOCH~ and, to a lesser extent, diketene. The discovery and develop- ment of new catalysts for reactions with ketene have now led to With the advent of the work of Degering (4)and Kung (IO)B the manufacture of p-lactones and enol acetates from carbonyl renewed interest has been taken in the utilization of ketene in the compounds and ketene. Staudinger (17)first described the for- synthesis of organic compounds. mation of @-lactonesby condensing diphenylketene with quinone. In the author's laboratories the condensation of ketene with In condensations with diphenyllietene, Staudinger used com- itself and with carbonyl *compounds-aldehydes, ketones, dike- pounds containing highly active carbonyl groups such as dibenzyl tones, keto esters, aromatic aldehydes and ketones, and unsatu- ketone, quinone, and benzophenone. The condensation reaction rated aldehydes and ketones-has been investigated. Other was carried out in the absence of catalysts and required elevated catalysts have also been found which are suitable for the conden- temperatures such that the decarboxylation products of the p- sation and in some instances they are superior to the Friedel- lactones rather than the p-lactones themselves were isolated-for Crafts type catalysts for the formation and isolation of p-lactones. example, benzophenone and diphenylketene give tetraphenyl- Aldehydes and a,p-unsaturated aldehydes and ketones were also ethylene and carbon dioxide. enol acetylated.

(CeH5)aCO + (CeHJ2 C=C=O +(CeHJz C=C(CoHs)z + GO1 DIKETENE More recently Kung (10)described the condensation of ketene, The dimerization of ketene should be considered in a study of CHz=C=O, with formaldehyde and acetaldehyde in the presence the condensation of ketene with carbonyl groups. Of the three of Friedel-Crafts type catalysts to form propionolactone and p- structures commonly assigned to diketene, p-vinylacetolactone butyrolactone, respectively. has been chosen as representing the product of the condensation of the carbon-to-carbon double bond of one ketene molecule with the CH*=C==O + CHZO/ZnCl%--+ CH2CH2C=0 carbonyl group of a second ketene molecule to form a p-lactone. LOJ CHz=C=O + CH,=C=O 50" C. CHz=$Xf;C=O and f No catalyst CHZ=C=.O + CH&HO/ZnClZ -3 CH,CHCH-C=O L-0-J CHaCOCH=C=O CHz=CCH&=O CHaC=CHC=O LO-1 LO--] A similar condensation with ketene and furfural and ketene and I I1 I11 benzaldehyde was reported by Hurd in 1933 (6) in which the p- lactone decarboxylation products, a-vinylfuran and styrene, re- Although many investigators show a preference for either P- spectively, were isolated. vinylacetolactone (11) or 0-crotonolactone (111) as representing 765 766 INDUSTRIAL AND ENGINEERING CHEMISTRY Vol. 41, No. 4 the structure of diketene, it is interesting to note that diketene then does not form @-alkoxy compounds with which is char- CH,COC€I-C=O +RCHzCH=CHCOCH3 + CO2 acteristic of the 0-lactones. Diketene (25)is manufactured in 90 to 95% yields simply by RCHz-CH-'b passing ketene in through a dispersion plate in the bottom of a J17ith acetaldehyde the product is 3-pentene-2-one; with pro- tower (Figure 1, omit formaldehyde and catalyst feed lines) filled pionaldehyde 3-hexen-2-one; and with butyraldehyde 3-hepten- with diketene and overflows continuously at the top of the tower. 2-one. The reaction is conducted by passing ketene into a solu- The rate of addition is controlled so that the liquid overflowing at tion of the aldehyde at room temperature. Conversions to unsat- the top of the tower is substantially free of dissolved ketene. urated ketones average between 50 and 65%, Temperature is the important factor in controlling the dimeriza- A similar condensation reaction is not observed with ketones. tion of ketene and at 40" to 50" C. a smooth rapid rate of dimeriza- Ketene and acet,onedo react, however, in the absence of a catalyst tion is obtained. The diketene is fed continuously to a still at at elevated temperatures, to form small amounts of isopropenyl reduced pressure, 30 mm., for final purification. Catalysts should acetate in addition to diketene. never be used in the production of diketene. CHz=C=O+CH,COCH,/BO O C. CHz=C(CHJ-OCOCHI Commercially ketene is produced by the pyrolysis of acetic acid --+ at reduced pressure, 40 to 100 mm. Where diketene is the desired ENOL ACETYLATIONS product it is prepared by inserting one or more scrubbers in series in the reduced pressure system. Ketene is fed into the scrubber With catalysts such as sulfuric acid (5),p-toluencsulfonic acid, (Figure 2, omit formaldehyde and catalyst feed lines) below the and particularly with acetylsulfoacetic acid in concentrations of packing support and scrubbed with diketene. 0.01 to 0.1% and at 40Oto 80" C., the corresponding enol acetates are formed. Acetylsulfoacetic acid is prepared by the reaction of Referring to the diagram, 1 indicates a primary scrubber which acetic anhydride with sulfuric acid: the acetic acid is distilled off may be cooled with water or other cooling agent through the cool- ing coil, 2. The scrubber is packed with Raschig rings and ketene at reduced pressure (8). is metered through rotameter, 7, and enters the scrubber through H2S04 + 2( CHsCO) ~O+CHSCO~SO~.~I€~COOHf2CHyCOOH the nozzle, 17, below a packing support. Diketene is circulated by a pump, 16, from the reserve tank, 5, through a cooled line, 13. CHFC=O + CH3CHO/Hd304 +CHFCHOCOCH~ The rate of flow of diketene through the scrubber is gaged by the rotameter, 15. The off-gas is led out at 22 and passes through a CI€?=C=O + CHaCOCIla/I12304 --+ CH2=C(CH3)0COCHa condenser, 9, and a liquid gas separator, 10, to the jet in the re- duced pressure system, Where a high throughput is desired two In the case of the aldehydes, the a,@-unsaturatedkelones \yvliich or more scrubbers are usually connected in series. A copper result froni the condensation of diketene with the aldehydes are scrubber 6 feet high and 8 inches in inside diameter packed with formed in increasing amounts as me ascend in the aldehyde series. 0.5-inch Raschig rings was used to produce 3 to 4 pounds of dike- tene per hour in 97% yield. Diketene is cycled through the scrubber at the rate of approximately 1 to 2 gallons per minute at 30" to 35' C. and is overflowed at 25 to the reduced pressure still. TABLEI. ESOLXCXTYLATIOK Unsaturated Enol Acetate Ketone, 0-Butyrolactone is produced by the hydrogenation of diLetene $.P., Conversion, Conversion, with Raney nickel catalyst at 60 to 70' C. and 300 to 500 pounds Carbonyl Compound C. % % per square inch in the presence of an equal or larger volume of dil- Acetaldehyde 72 21 17 Propionaldehyde 99 18 34 uent. @-Butyrolactone, , and other inert hydrocarbon Butyraldehydo 128 7 51 -4oetone 96 45 None solvents are suitable as diluents. In the absence of diluents the RIethyl ethyl ketone 118 31 None hydrogenation cannot be controlled and the diketene decomposes with violence. CH2=CCH&=0 + Hz diluent CH3CHCH&=0 The conversions are bnsed on the ketene added. Sulfuric acid L-OJ -+ -01 was used as the catalyst. With acetylsulfoacetic acid as a cnta- Ni(R) lyst, greatly increased conversions to the enol acetates are ob- GO" to 70' C. tained-e.g., with acetone the conversion to isopropenj-1 acetate 500 pounds per square inch is 75 to 8570 as compared with 35 to 45% for sulfuric acid cata- lyst. Anhydrous sodium acetate is also a catalyst for the enol On increasing the hydrogenation temperature to 120 O to 160 * C. @-butyrolactoneundergoes hydrogenolysis to n-butyric acid. acetylation of acetone with ketene. CH,CHCHzC=O + HZ --+ CH3CHzCHzCOOH p-LACTOhES LO-_I Ni(R) 120Oto 150" C. In the presence of suitable condensation catalysts, aldehydes and ketones condense with ketene to form @-lactones. Some of In continuous hydrogenation diketene can be hydrogenated di- the better catalyst materials include boric acid, triacetyl borate, rectly to butyric acid. mercuric chloride, chloride, zinc thiocyanate, magnesium pel chlorate, and boron trifluoride etherate. REACTIONS OF KETENE WITH ALDEHYDES AhD KETONES Catalysts suitable for use In the condensation of ketene with Ketene and aliphatic aldehydes such as acetaldehyde, propion- carbonyl compounds generally fall within the classification of a aldehyde, and butyraldehyde react in the absence of catalyst to group of salts which are strongly acid in concentrated aqueous form a,p-unsaturated ketones. solutions (Id). The compounds are capable of forming coordina- tion complexes with hydroxy groups and also have a strong cata- 2CHz=C=0 + RCHzCHO RCH&H=CHCOCHj + COz lytic activity towards carbonyl derivatives These compounds in- clude the borates, aluminates, halides, thiocyanates, nitrates, Actually the ketene dimerizes to diketene and as such reacts chlorates, and perchlorates of zinc, tin, mercury, aluminum, lith- with the aldehyde to form a 0-lactone which decarboxylates upon ium, boron, iron, manganese, and cobalt. heating to form the a,P-unsaturated methyl ketone (1). The inactivity of some salts of this group is generally due to CH,COCH=C=O RCHnCHO +CH3COCH--C=O their insolubility in the reaction solution. + Although this list includes the Friedel-Crafts type of catalyst, most of the compounds are not Friedel-Crafts catalysts. The cata- April 1949 INDUSTRIAL AND ENGINEERING CHEMISTRY 767

polyoxymethylene acetates due to the prep- ence of water in the 95% paraformaldehyde CONDENSER which is vaporized in the depolymerization and enters the reactor. Under anhydrous con- ditions yields of propionolactone as high as 96% have been obtained. The reduced pressure reactor (Figure 2) used in the manufacture of diketene was also used in the production of lactones. The apparatus shown is charged with 50 PUMP grams of zinc chloride in 5 gallons of propiono- lactone which is circulated through the scrubber, 1, at 1.5 to 2 gallons per minute. Paraformal- dehyde is depolymerized at 19, metered through a heated rotameter, 8, and mixed with gaseous ketene immediately before entering the scrubber through the nozzle, 17, which is centered below the screen supporting the packing. The reaction temperature is held at 5' to 10' C. by cooling. There are two factors on which the choice of a reaction temperature depends: (1) to obtain a fast rate of reaction between ketene and formal- dehyde so as to minimize the amount of homo condensations due to the presence of high con- centrations of the monomers in solutions, and (2) to minimize the formation of linear polyesters of the @-lactone. Figure 1. Condensation Reactor In a 48-hour run 3.5 grams of ketene per minute and 2.5 grams of formaldehyde per minute were mixed immediately before entering lyst activity depends on the solubility of the metal salt as well the scrubber. Catalyst make-up was added intermittently as the degree of diwociation in organic media, With aldehydes at 4 and a concentration of 0.05 to 0.25% was maintained. Pro- * pionolactone was taken off continuously at 25, fed to a flash and ketones the effective metal salts Can be thought of as forming heater, and then redistilled. A yield of 88% propionolactone, 3% an oxonium'type complex with the carbonyl group. acrylic acid, and 9% residue was obtained. The choice of a catalyst is important if a high yield of @-lactone is to be obtained. This choice of a catalyst depends on the reac- tidy of the particular carbonyl compound to be condensed with TABLE11. PROPIONOLACTONE ketene. For example, with aldehydes (particularly the lower ali- Conversion Mole phatic aldehydes, formaldehyde and acetaldehyde, and aromatic To di- To Ratio aldehydes) the preferred catalysts are boric acid, triacetyl borate, Ketene, CHIO, ZnCh, T, To lac- ketene acrylio Red- Keten$/ Run Grams Grams % ' C. tone acid acid due CHzO zinc thiocyanate, and zinc chloride. Acetone, methyl ethyl ke- 7 15 1.10/1 15 3050 2142 3 0 78 3 tone, methyl pyruvate, and diacetyl require strong condensation 16 3360 2023 3 10 60 4 12 24 1 19/1 12 6 1.03/1 catalysts such as boron trifluoride etherate or acetic acid complex ix :;;i :gig !:: ii !i . 2 14 10 1 05/1 to obtain maximum yields. Zinc chloride acetic acid complex and 20 1990 1422 0.3 10 84 . I 11 5 1 02/1 22 1095 760 . . , 0 3 23 . 71 1.02/1 the metal fluoborates of zinc, iron, and tin can also be included in 23 1440 1031 . , 40 7 21 . 62 0.97/1 this group. In carrying out the condensation of ketene with aldehydes continuously, it is preferred to add the ketene and aldehyde in equimolar amounts to a solution of the catalyst in the cor- responding lactone. Other solvents such as ethers, alkyl halides, and ketones are also suitable and are preferred in batchwise operation because of the polymerization tendency of the @-lactones.

PROPIONOLACTONE Ketene and formaldehyde are metered sepa- rately and passed into a solution of zinc chloride in propionolactone. The solution is cycled through the column concurrent with the flow of incom- ing gases and is maintained at approximately 10' C. by cooling. The lactone is overflowed continuously through a rotameter to a small flash heater at reduced pressure. The crude lactone is then redistilled to remove acrylic acid. Typical results are reported in Table 11. It was found that some propionolactone is formed even in the absence of any catalyst. Although the temperature was 40" C. in run 23 and 7% propionolactone was obtained, no acrylic acid was isolated by destructive distilla- tion of the residue. The residue formed in the presence of catalysts is comprised largely of Figure 2. Reduced Pressure Reactor for Ketene Reactions 768 INDUSTRIAL AND ENGINEERING CHEMISTRY Vol. 41, No. 4

Table 111. Products from Aliphatic Aldehydes and Ketones Carbonyl Compound Lactone Reduction Polymerization and Pyrolysis Alcoholysis (9) Decarboxylation Formaldehyde Propionolactone Propionic acid Acrylic acid 8-Alkoxypvopionic acid Ethylene Acetaldehyde P-Butyrolactone Butyric acid Crotonic acid P-Alkoxybutyric acid Propylene Acetone 0-Methyl-8-butyrolactone Isovaleric acid P,8-Dimethylacrylic acid 8-Alkoxyisovaleric acid Isobutylene Methyl ethyl ketone 8-Ethyl-B-butyrolactone 3-Methylpen- 8-Methyl-p-ethylacrylic acid 2-Alkoxv-2-methvl_. uentanoic 2-Methvl-1-butene tanoic acid acid Butyraldehyde 8-Propylpropionolactone Caproic acid 8-Propylacrylic acid P-Alkoxycaproic acid I-Pentene

Propionolactone can be purified by redistillation at 28" C. and Furfural gave only tars and uncontrollable reactions with zinc 3 mm. to give a product showing no unsaturation on the infrared chloride and similar catalysts. Furacrylic acid and cinnamic acid spectrometer. The pure lactone has the constants: n"," 1,4135, dEo 1.1489, melting point -31.2" C., boiling point 51" C. at 10 were prepared by the reaction of ketene with furfural and benxal- mm. dehyde, respectively, at GOo C. using sodium acetate catalyst fol- Acetaldehyde and ketene reacted similarly, using a solution of lowed by destructive distillation. Yields were 40 to 60%. 0.25% zinc chloride in p-butyrolactone. An 85% yield of P-buty- rolactone ras obtained. Diketene and methyl propenyl ketone UNSATURATED ALDEHYDES AND KETONES are by-products. Unsaturated aldehydes and ketones can react with lret me to With ketones such as acetone and methyl ethyl ketone the re- give a variety of products. In the presence of suitable conden- action is carried out in the presence of excess ketone, which is sation catalysts ketene adds both 1,2 and 1,4 to form p(1)- and recovered and recycled. a( 11)-lactones. CHaCOCHa + CHeC=O --+ CHs-C(CH8)-0 4 32 1 RCH=CR-CR=O CHt=C=O/ZnCl2 0 to 10 O 0. 0°C. I + BF3etherate CH2----&=0 + RCH=CR-CR-CHz $. RCHCRcCRO 11 I I b.p. 54" C. at 10 rnm. O--C=O CH2 c=o and I I1 CHsCHzCOCHs CHz=C=O CHaCHzC(CHa)-0 + + can be hydrogen, alkyl, aryl. AHz---C=O I R or I The &lactones are decarboxylated by pyrolyzing 0.r heating at temperatures above 100" to 120" C. to form diene derivatives. b.p. 60" to 61 O C. at 10 min. &Lactones decarboxylate at slightly higher temperatures and As the molecular weight increases the problem of isolating the also form diene derivatives. lactone becomes more difficult because of a tendency to decar- RCH=CR-CR-CH2 A RCH=CR--CR=CH2 + Cod boxylation. However, once the p-lactones are isolated in the pure 1 --f state, they are stable compounds at rooin temperature. 0-Lo If an unsaturated acid is desired as the final product, the reac- RCHCR=CRO tion between ketene and the carbonyl compound is carried out at I I A CHz=CR--CR=CHR + COz 40 O to GOo C. to give a low molecular weight linear polyester of the CHz-----C=O + @-lactonedirectly. This linear polyester is then depolymerized P-Lactones are usually formed in the ratio of 10 to 1 of the delta by distillation to form the a,p-unsaturated acid (b,lf ). lactones as calculated from the yield of olefinic decomposition CHa=C=O + CHZO/ZnCl2 40" to 60" C. -OCHzCH2CO- products obtained from the condensation of crotonaldehyde with + ketene (Table IV). If a doubly unsaturated acid is the desired [OCHZCI~ZCO]-OCH&IIzCO product, the condensation is carried out at 40' to 50" C. and a product is obtained comprising largely the linear polyesters of the -CO [OCH~CH~CO],O/CU(OAC)~A CHz-CHCOOH --+ lactones. Destructive distillation at reduced pressure result5 in the formation of the doubly unsaturated acid. Sorbic acid is In this particular case a small amount of copper acetate is added manufactured in 70 to 80% yields in this may from crotonaldchyde as an inhibitor to vinyl polymerization prior to the distillation. and ketene. Some of the products which are obtained from aliphatic aldehydes With enol esterification catalysts, and at 50" to 80" C., the wr- and ketones with ketene via the p-lactones are listed in Table 111. responding acetoxy dienes are formed. For example, 1-ace1oxy-

AROMATIC ALDEHYDES AND KETONES TABLE USSATURATED -4LDEHYDES AND l

1,a-butadiene is produced by the reaction of ketene with crotonal- @-lactoneincreases, and higher yields of the unsaturated esters are dehyde in the presence of sulfuric acid at 60 O to 80 O C. obtained. Hydroxydicarboxylic acids can be formed by hydroly- sis of the crude lactone, and with alcohols the corresponding al- 60-80 O C. CHZ=C=O + CHaCH=CHCHO/HzS04 koxydicarboxylic acid diester is produced. CH2=CHCH=CHOCOCHs HYDROLYSIS

Some of the products which have been formed with the com- CH&(CHg) --CHzCOOCzHs + mon ~l,punsaturated aldehydes and ketones are reported in Table O=LB + NaOH, HC1 IV. All these products are useful in resins, drying oils, etc. The HOOCCHzC(CHs)-CH&OOH + CzH5OH enol acetates form both rubbers and resins and can be polymer- AH ized and copolymerized. ALCOHOLYSIS DIKETONES Ketene condenses with to form the mono- and di-p- lactones. In the absence of excess ketene the decarboxylation products indicate the formation of both the mono- and di-&lac- CZH~OOCCH~C(CHI) -CHzCOOC2Hs tones. dCaHs For example, 86 grams of diaoetyl were diluted with 250 ml. of ethyl ether containing 12 ml. of boron trifluoride etherate and 2 ram moles of ketene were passed in through a high speed stirrer. Enol acetylation of methyl pyruvate gave a low yield of methyl !!he catalyst was neutralized with anhydrous sodium acetate and a-acetoxyacrylate. and ethyl levulinate led the mixture was distilled at atmpspheric pressure. Four grams of to a mixture of isomers-e.g., with acetoacetic . 2,3-dirnethyl-lJ3-butadiene,bo.il?ng point 68 O Cb!and 12 grams of methyl isopropenyl ketone, boihng point 95-98 C. were isolated CH&OCHzCOOC~Hs+ CHz=C=O/HzSO4 60-80A C in addition to 47 grams of unchanged diacetyl. oo c. 0 0 CH3COCOCI33 + 2 CHz=C=O BFetherate-) ' CHz==C--CHz bOCz& + CHsC=CH E OCzHs CHzC(CH3) COCHs CHzC(CHs) C(CHJ CHo bCOCH8 bCOCH3

6=L-0 + o= A'-0 A-d-o The enol acetates of acetoacetic ester rearrange A CH&(CHJCOCHs -+ CH~=C(CH~)COCHI COz on prolonged heating in the presence of acid catalysts + to form ethyl diacetylacetate. This compound boils o= A'-0 slightly below the mixture of enol acetate isomers and has a higher index of refraction n2: = 1.4690 CHpC(CHs)~(CHa)~&- * + CHz=C(CHdC(CHs)=CH2 4- 202 as compared to 1.4420 for the enol acetate isomers. II o=LO The enol acetates of the ketoesters can be copoly- a--(5=0 merized with polymerizable vinyl monomers in the Degering (16)and Hurd (7)both reported the acetylation of the presence of peroxide catalysts to give clear, colorless resins. Some enol forms of diketones with ketene in 1944. It is interesting to of the compounds which can be prepared from keto esters and '

note that whereas the mono and dienol acetates of diacetyl and ketene are reported in Table VI. , can be prepared, acetonylacetone is only cyclized under acetylation conditions and no enol acetates have been iso- lated. Under condensation conditions the decarboxylation prod- TABLEV. REACTIONPRODUCTS OF KETENE WITH DIKETONES ucts of both the mono- and di-@-lactonesfrom acetonyl acetone Carbonyl Condensation Conditions and ketene were isolated. The products of the reaction of ketene Compound Decarboxylation Product; Enol Acetylation Produots with diketones under both condensation and enol acetylation Diaoetyl 14% methyl isopropenyl 4% or-acetoxyvinyl methyl ketone 1.7%ketone, 2 3-diacotoxy-1 b.p.5 3Ze C. 3- conditions are summarized in Table V. 5% 2 3-dimeth~l-l.3-buta- dieie, b.p.rss 68' C. butahiene, b.p.6 53&C. Aoetylacetone 27% 4-methyl-4-penten-2- 43% I-methyl 2-acetylvinyl ' KETO ESTERS one b.p.785 127' C. acetate, b.p.10 84O C. 14% '2,4-dirnethyl-l 4-pen- 18% 2,4-diacetoxyplperyl- Methyl pyruvate, ethyl acetoacetate, and methyl levulinate tadiene, b.pm 88O' C: ene, b.p.la 114' C. Acetonylaoetone 2,5-Dimethyl-l,5-hexa&ene, 85% 2,5-dimethylfuran also reacted with ketene under condensation and enol acetylation 5-Methyl-5-hexene-Z-one,b.p.?84 112' c. conditions. No effort was made to isolate the 8-lactones but the b.p.784 154' c. decarboxylation products were isolated instead. Methyl pyru- vate reacts with ketene to form a &lactone, which is then decar- boxylated to form methyl methacrylate. TABLEVI. PRODUCTSOF KETO ESTERS AND KETENE Carbonyl Condensation Conditiono, 0°C Compound Deoarboxylation Products Enol Acetylation Product CHsCOCOOCHa+ CHa==C=O/BF3 etherate __.f Methyl 14% methyl methacrylate Methyl a-acetoxyacrylate, CHa C(CHa)COOCH~ pyruvate b.p.io 62" C. Ethyl 84% ethyl isopropenyl- 70% ethyl 3-acetoxycrotonate o=c-'b acetoacetate acetate, b.p.eo 54.5' C., and isomer, b.p.to 94O C., nv 1.4400, d$' 1.0159 nZ,O 1.4420, dgg 1.0659 CHz--C(CHs)-COOCH3 +CH2=C(CHs)-COOCH3 Ethyl diacetylacetate, b.p.10 I/ 89' C.. ny 1.4690 Methyl, Methyl 8-isopropenylaro- O=%-d levulinate pionate; b.p.zo 54' C., ny 1.4224, dg0.9346 Ethyl 38% ethyl 4-aoetoxy-4-pen- Ethyl acetoacetate and methyl levulinate undergo the same levulinate tenoate and isomer, b.p.6 condensation to form unsaturated esters. As the carbonyl group 8Q0 C.,n2,O 1.4361, diz 1.0478 is removed from the carboxyl group the ease of formation of the 770 INDUSTRIAL AND ENGINEERING CHEMISTRY Vol. 41, No. 4

REACTIOR OF KETERE WITH HYDROCYANIC ACID (8, 18) The reaction of ketene with hydrocyanic acid shows the forma- TABLE I'II. REACTIONOF TCsmm VI'ITII HYDROCYANICACID tion of an enolizable kctonitrile which is subsequently acety- Acetoxy- (IC) acrylo- lated to form the enol acetate. The reactions which occur are Conversion, yo nitrile Ketene Ketene Resin Yield on represented by the equations to di- Yield, % of' Ketene, IICN Ketene ketene c70 Total Average % CH*=C=O + HCN + CH3COCN +CII2=C(OH)CN So catalyst 24 40 44 78 6.5 12 runs 34 0.0870 XaOAc 42.5 70 14 74 18.0 12 runs 60 0.34, KaOAc 70 88 0.1 88 8.7 7 rnns 88 then 0.457, NaOAc 58 67 2.5 66 30 12 rnns 63.5 CHZ=C(OH)CK f CH2=C=O CHz==C(OCOCH,)CS

In addition to a-acetoxyacrylonitrile a small amount of the a-,~cetoxyisosuccinicdinitrile can be formed alniost to the ex- dimer of pyruvonitrile is also formed clusion of a-acetoxyacrylonitrile by carrying out the reaction with hydrocyanic acid as a 50% solution in acetic acid at 0" C. 2CHaCOCN -+ CHJCO~C(CN)~CH~a-acetoxyisosuccinic and with 0.370 sodium acetate catalyst. Less than 10% acetic dinitrile anhydride is formed as a by-product. The dimer can be pyrolyzed at elevated temperatures or dis- tilled in the presence of basic catalysts such as sodium acetate to LITERATURE CITED * yield a-acetoxyacrylonitrile and hydrocyanic acid. Boese, A. B., U. S. Patent 2,108,427 (Feh. 15, 1938). The reaction of ketene with hydrocyanic acid is carried out by Ibid., 2,382,464 (Aug. 14, 1945). Dommoni, T. F., and Cuneo, J. F., Zbid., 2,411,823 (Nov. 26, passing ketene into hydrocyanic acid in the presence or absence of 1946). diluents, at -10" to +loo C. Diluents are used mainly to reduce Gwynn, B. H., and begering, E. F., J. Am. Chem. SOC.,64, 2216 the vapor pressure of the hydrocyanic acid and a-acetoxyacrylo- (1942). nitrile itself is a preferred diluent for the reaction. Although con- Gwynn and Degering, U. S. Patent 2,383,966 (1942). Hurd, C. D., J. Am. Chem. SOC.,55, 275 (1933). siderable reaction is obtained in the absence of catalyst, the high- Hurd, C. D., Edwards, E. E., and Roach, J. I<.,Ibid., 66, 2013 est yields are obtained with a mildly basic catalyst. Anhydrous (1944). sodium and potassium acetate are superior to the alkali cyanides Johnston, F., and Newton, L. W., U. S. Patent 2,395,930 (March and tertiary nitrogenous compounds as catalysts. 6, 1946). Kung, F. E.,Ibid., 2,352,641 (JuEy4, 1944). In this reaction an optimum concentration of catalyst has been Ibid., 2,356,459 (Aug. 22, 1944). observed. With no catalyst or too low a concentration of cata- Ibid., 2,361,036 (Oct. 24, 1944). ljrst, diketene is formed in large amounts. With too high a con- hfeerwein, Ann., 455, 227 (1927). centration of catalyst the dimerization of pyruvonitrile increases Mugdan, M., and Sixt, J., U. S.Patent 2,216,450 (Oct. 1, 1940). Roy, G. C., Ibid.,2,396,201 (March 5, 1946). and considerable amounts of a-acetoxyisosuccinic dinitrile are Spence, d. A., and Degering, E. F.,J. Am. Chem. Sac., 66, 1624 formed. (1944). A comparison of average results with and without sodiuni ace- Staudinger, Ann., 384, 51 (1911). tate catalyst is reported in Table VII. These runs were carried Staudinger and Kon, Ibid., 384, 38-135 (1911). Trollman, Schlaffer, and Ostrowski, German Patent 736,504 out operating continuously using the column shown for dilcetene (1943). and propionolactone (Figure 1). Unreacled hydrocyanic acid RECEIVEDMarch 8, 1948. Presented in the Symposium on Industrial was separated from the product by distillation and recycled to the Processes, American Bssociation for the Adranoemont of Science, Chicago, reactor, The residue was mainly a-acetoxyisosuccinic dinitrile. Ill., December 26, 1947.

Relations for

J. W. WILSON AND GEROULD H. SMITH Union Oil Company of California, Oleum, Calif.

MARKED advance in the measurenient of the viscous prop- erties of lubricating greases was disclosed by Arveson (1) Ain papers published in 1932 and 1934. His results were obtained on a novel apparatus employing constant flow rate rather than As lubricating greases are non-Kewtonian in character, differ- constant pressure. Beerbower, Sproule, Patherg, and Zimmer ent values of qa will be obtained for a grease at diffcrcnt rates of (2) have developed a simplified apparatus of lhis type in n-hich flo~in a given capillary, or at a given rate of flow in capillarics constant flo~rate is obtained by means of hydraulic oil and an with different radii. Arveson showed that by plotting qa against accurate metering pump. This apparatus, which is known as the the expression 4Q/n-IP, most suitably on logarithmic scales, S.O.D. pressure viscometer (Precision Scientific Company, Chi- smooth curves could be obtained. This expression, 4Q/n-R3, Cali cago, Ill.) has led to a large amount of work on the flow char- he shown mathematically to be the rate of shear, S, at the wall of acteristics of lubricating greases (e,.$, 8,9, 11, 13). a capillary for the flow of a Nevtonian fluid. For a lion-Sew- Arwson used his data to calculate consistency values, which he tonian fluid, the cxprcssion only approsirnates the rate of shear at, termed "apparent viscosity," va, by means of the Poiseuille the wall; nevertheless, there are abundant data obtained with equation : the S.O.D. viscometer t'o indicate that if the dimensions of two