US2067473A - Hydrolysis of isobutyl chloride - Google Patents

Description

Patented jazz. 12, 1937 ,eswa

r rare HYDRQLYSIS 0F ISOBUTYL CHLORIDE No Drawing. v Application April 18, 1934, Serial No. 721,154

11 Claims.

This invention concerns an improved method of hydrolyzing isobutyl chloride, whereby isobutyl alcohol, tertiary butyl alcohol, and isobutylene are produced simultaneously. It also concerns procedure for controlling the relative yields of said products from the hydrolysis.

Isobutyl chloride is known to be more difficultiy hydrolyzable than are most alkyl halides. For instance, Freund, J. pr. (2) 12, 25, reported that isobutyl chloride was not hydrolyzed to an appreciable extent when heated with water in a sealed tube at C. for 12 hours. Niederist, Ann. 186,388, found that isobutyl iodide was only partially hydrolyzed when heated with water in a sealed tube at C. for 40 hours. By separating the unreacted isobutyl iodide remaining after such treatment and retreating it in the same manner he succeeded in bydrolyzing the major portion of the iodide. He reported 1sobutyl alcohol to be the product of his hydrolysis. Niederist did not describe the hydrolysis of isobutyl chloride, but stated that it behaved similarly to the iodidewhen treated in like manner.

We have now found that isobutyl chloride can readily be hydrolyzedby heating the same under pressure to a temperature above 95 C. with an aqueous base and that isobutyl alcohol, tertiary butyl alcohol, andisobntylene are the products from such hydrolysis. We have also found that the relative yields of the several products may be varied by changing the kind of base used, the relative proportions of the reactants, etc. We have further found that by acidifying the hydrolyzedreaction mixture and continuing to heat the same under pressure, the yield of tertiary butyl alcohol can be increased considerably and the yield of isobutylene reduced.

To the accomplishment of the foregoing and related ends, the invention consists in the method hereinafter fully described and particularly pointed out in the claims, the following description and examples setting forth in detail only certain of the various ways in which the principle of our invention may be employed;

The hydrolysis of isobutyl chloride is carried out by heating the compound under pressure to a, temperature above 95 C. with an aqueous solution or suspension containing approximately its chemical equivalent or more of an inorganic base, e. g. a hydroxide oi sodium, potassium, calcium, barium, lead, or iron; a. carbonate of sodium, potassium, calcium, or barium, etc. The hydrolysis may be carried out at temperatures as high as 500 6., but is preferably carried out between 120 and 350 C. The hydrolysis may be carried out in any of the usual types of high pressure reactors, for instance, in a tubular autoclave.

The relative yields of isobutyl alcohol, tertiary butyl alcohol, and isobutylene from the hydrolysis are dependent upon the particular conditions uncarbonate, rather than an alkali metal hydroxide,

as the hydrolyzing agent results in an increased .yield of tertiary butyl alcohol and a decreased yield of isobutylene;

(3 An increase in the ratio of water to isobutyl chloride in the reaction mixture results in an increase both'in the yield of tertiary butyl alcohol and in the rate at which the hydrolysis occurs; and

(4) A change in the reaction temperature does not ordinarily result in any great change in the respective yield of the several products, but as the reaction. temperature is raised above 300 C. there is usually a noticeable decrease in the yield of the alcohol products and increase in the yield of isobutylene, and such changes in yields become more pronounced as the temperature is raised.

In hydrolyzing isobutyl chloride to produce isobutyl alcohol as the principal product, we prefer to heat the isobutyl chloride under pressure to a temperature above 120 C. with at least 3 times its weight of a not more than 3 normal aqueous solution of an alkali metal base, e. g. a hydroxide, carbonate, or bicarbonate of sodium or potassium.

Isbutylene is produced in maximum yield when a relatively insoluble base, e. g. a hydroxide of calcium, barium, magnesium, iron, etc., is-used as the hydrolyzing agent and the reaction is carried out at a high temperature, particularly above 300 C.

Tertiary butyl alcohol is produced in maximum yield from the hydrolysis when a mild base, e. g. calcium hydroxide, sodium carbonate or bicarbonate, etc., is used as the hydirolyaing agent, the molecular ratio of water to isobutyl chloride in the reaction mixture is high, e. g. above 30, and the reaction is carried out below 300 C.

The time required to complete the hydrolysis varies from less than one minute to several hours, depending upon the temperature at which the hydrolysis is carried out, the kind and pro portion of base employed, etc. The completeness of the hydrolysis may readily be determined at any time by withdrawing an aliquot portion of the reaction liquor and analyzing it for inorganic chlorides. When inorganic chloride is found to have been formed in amount chemically equivalent to the isobutyl chloride employed, the hydrolysis is complete.

Following the hydrolysis, the isobutylene conacid solution having a strength from 0.02 to- 2 normal, but a larger or smaller proportion of acid may be used if desired.

After the reaction according. to any of the above procedures is completed, the reactor is cooled and gaseous isobutylene is released therefrom and collected in a suitable receiver. The liquid mixture isthen fractionally distilled to separate the isobutyl and tertiary butyl alcohol products as relativeLv concentrated aqueous solutions thereof. Either of said alcohols may, of course, be dehydrated completely by known procedure, e. g. by distilling the same in the presence of calcium oxide. 1 l

The following table, which shows a number of experiments wherein isobutyl chloride was hydrolyzed'by thepresent method, illustrates the changes in yields of the several products which result from certain changes in the conditions under which the hydrolysis is carried out. Each experiment was carried out by heating a reaction mixture, having the composition stated in the table, in a closed reactor with agitation .at the temperature and for the time also stated in the table. After the heating operation was completed, the reactor was cooled and isobutylene was released therefrom and collected in a gas receiver.

An aliquot portion of the reaction liquor was. analyzed to determine the inorganic chloride In the foregoing table, comparison between runs 1-4, wherein aqueous calcium hydroxide is used as the hydrolyzing agent, shows that in general an increase in the ratio of water to isobutyl chloride in a reaction mixture results in an increase in the yield of tertiary butyl alcohol and a decrease in the yield of isobutyiene, but that as said ratio becomes higher the change in yields resulting from a further unitary change in ratio is less pronounced. A comparison of runs 5 and 8 shows that when an aqueous sodium hydroxide solution is used as the hydrolyzing agent an increase in the ratio of water to isobutyl chloride likewise results in an increase in the yield of tertiary butyl alcohol and a decrease in the yield of isobutylene. Similar results are obtained when other inorganic bases are used.

In runs 3 and 4, wherein calcium hydroxide was used as a hydrolyzing agent at widely different temperatures, but under otherwise comparable operating conditions, and in runs 6 and 'I wherein sodium hydroxide was employed at wide- A comparison of run 6 with runs 2, 10, and 11 shows'that by employing a water-soluble metal hydroxide, e. g. sodium hydroxide, as the 'hydrolyzing agent rather than a metal hydroxide which is relatively insoluble in water, e. g. a hydroxide of calcium, lead, or magnesium, the yield of isobutyl alcohol becomes increased while the yields of tertiary butyl alcohol and isobutylene are each lowered. v

'l 'romacomparisonofrunsaand 9withr1ms 2, 6, '10, and 11, it will be noted that by using an alkali metal carbonate or bicarbonate as the hydrolyzing. agent, rather than a metal hydroxide under otherwise similar operating conditions,

each of the alcohol products are formed in high yield and the yield of isobutylene is lowered.

Regardless, of the exact procedure employed in carrying out the hydrolysis reaction, the yield of tertiary butyl alcohol can be increased at the expense of the isobutylene product by acidifying the hydrolyzed mixture with a strong acid, e. g. sulphuric or hydrochloric acid, preferably in on the quantity of isobutyl chloride reacted. amount suflcient to form a, 0.02to 2 normal Table Beaotionmisture Yields B Mole g Conver- B No. Isorstio 1 equiva- M. W"

butyl 011110 lentsof Tertiary gg; 3312, m; 1% 41.1% 3 1 "in mm mm mm Moles ride 0 010 5 2.21 50.1 11.1 1.08 4 ms 25.5 12.0 a5 15. 4 c4 0 1 2.15 see 22.2 1.0a 4 25.2 21.11 21.1 a. 2 or on, 1.11s saa n2 we 4 10s cs1 21.1 21.0 45 4 or on, 2.10 205.5 51.4 1.05 0.25 220 01.5 23.6 25.0 41. 5 4 a 1.2 50.1 11.1 .1.20 4 1110 211.1 42.1 0.2 15 4 NsOH 4.22 ass as 1.01; 4 155 21.5 41.2 0.1 41. 4 H1103 4.12 ass :22 1.05 1105 1100 11.2 51.1 10.4 41. 1; X400: 4.12 111.1 2.2 1.011 4 155 01.2 411.1 21.0 10. a NaHO05 a. 111.1. 22.2 1.02 4 155 sas 45.1 22.2 10 10 4 Page 1 1e sas 222 1.11s. 4 115 2110 22.0 21.5 52 u 4 mo 1 2.10 511.11 22.2 1.011 4 115 02.5 20.4 111.5 a.

monocular-queer aqueous acid solution in said mixture, and thereafter heating the mixture under-pressure between 75 and 150 C. Such mode of increasing the yield of isobutylene product is illustrated by the comparative experiments described in the following example.

Example (a) A mixture of 8 moles of isobutyl chloride, 8.4 moles of sodium hydroxide, and 205.5 moles of water was heated in a bomb, with agitation, at 220 C. for 10 minutes. The bomb was then cooled and gaseous isobutylene was released therefrom and collected. A 5 cubic centimeter sample of the reaction liquor was analyzed for inorganic chlorides, it being found that 99.5 per cent of the isobutyl chloride was reacted. The main body of reaction liquor was then iractionally distilled, whereby a small additional quantity of isobutylene was collected and the alcohol products were separated as relatively concentrated aqueous solutions thereof. The per cent of theoretical yields of the several products, based on the quantity of isobutyl chloride reacted, were as follows:- isobutyl alcohol, 39.9 per cent; tertiary butyl alcohol, 7.5 per cent; and isobutylene, 45.2 per cent.

(b) A mixture of isobutyl chloride, sodium hydroxide, and water in the proportions stated in the above experiment (a), was heated in a bomb, with agitation, at 220 'C. for 10 minutes. The bomb was then cooled and suflicient sulphuric acid was injected into the same under pressure to neutralize any unreacted sodium hydroxide remaining therein and to form, with the water in the reaction mixture, a 0.16 normal aqueous sulphuric acid solution. The acidified mixture was heated with stirring between 100 and 107 C. for 2 hours. The bomb was then cooled, gaseous isobutylene was released, and the reaction liquor was discharged. A 5 cubic centimeter portion of the liquor was analyzed for chloride content, it being found that 97.7 per cent of the isobutyl chloride had been reacted. The main body of reaction liquor was then fractionally distilled to separate the products contained therein. The per cent of theoretical yields of the several products, based on the isobutyl chloride consumed in the reaction, were:isobutyl alcohol, 41.6 per cent; tertiary butyl alcohol, 30.7 per cent; and isobutylene, 10.7 per cent.

In the experiments described in the above example it will be noted that by acidifying the hydrolyzed reaction mixture and again heating it under pressure, the yield of tertiary butyl alcohol was increased by more than 4 times and the yield of isobutylene was reduced to a corresponding extent.

The isobutylene produced by our method is sometimes contaminated with normal butylenes and diisobutylene, which may also be formed in the hydrolysis, but the combined yield of said lay-products is 'usuallylow, e. g. below 7 per cent of theoretical.

Other modes of applying the principle of our invention may be employed instead of those explained, change being made as regards the meth- 0d herein disclosed, provided the step or steps isobutylene, isobutyl alcohol, and tertiary butyl alcohol from the reacted mixture.

2. The method which comprises heating isobutyl chloride with at least its molecular equivalent of a metal base in the presence of water at superatmospheric pressure to a reaction ternperature above C. and thereafter separating isobutylene, isobutyl alcohol, and tertiary butyl alcohol from the reacted mixture.

3. In a method wherein a mixture of isobutyl chloride, water, and an inorganic base is reacted under pressure at an elevated temperature to form isobutyl alcohol, tertiary butyl alcohol, and isobutylene, the steps for increasing the yield of tertiary butyl alcohol which consist in acidifying the reacted mixture with a compound selected from the class consisting of'strong acids and salts capable of undergoing hydrolysis to form strong acids and heating the acidified mixture at super-atmospheric pressure to a temperature between about 75 and about 150 C.

4. In a method for making isobutylene, the steps which consist in heating a mixture of isobutyl chloride, water, and a slightly soluble metal hydroxide to a reactiontemperature above 100 C. at.superatmospheric pressure and thereafter separating isobutylene from the reacted mixture.

5. In a method for making isobutylene, the steps which consist in heating a mixture of isobutyl chloride with an aqueous mixture containing approximately its chemical equivalent of a slightly soluble metal hydroxide to a reaction temperature above 100 C. at superatmospheric pressure and thereafter separating isobutylene from the reacted mixture.

6. In a method for making isobutyl alcohol and tertiary butyl alcohol simultaneously, the steps which consist in heating a mixture of isobutyl chloride with at least 30 times its molecular equivalent of water and approximately its chemical equivalent of a water-soluble base selected from the class consisting of alkali metal carbonates and bicarbonates at superatmospheric pressure to a reaction temperature above about C. and thereafter fractionally distilling the reacted liquor to separate isobutyl alcohol and tertiary butyl alcohol therefrom.

7. In a method for making tertiary butyl alcohol in good yield, the steps which consist in heating a mixture of isobutyl chloride with at least 30 times its molecular equivalent of water and approximately its chemical equivalent of a base selectedfrom the class consisting of alkali metal carbonates and bicarbonates and slightly soluble metal hydroxides at superatmospheric pressure to a reaction temperature above 120 C. and thereafter fractionally distilling the reacted liquor to separate tertiary butyl alcohol therefrom.

8. In a method of making tertiary butyl alcohol in good yield, the steps which consist in heating a mixture of isobutyl chloride with at least 30 times its molecular equivalent of water and approximately its chemical equivalent of a base selected from the class consisting of alkali metal carbonates and bicarbonates and slightly soluble metal hydroxides to a reaction temperature above about 120 C., thereafter acidifying the mixture with mineral acid to form an aqueous mineral acid solution having a strength droxide at superatmospheric pressure to a re- 75 action temperature/above 100 C. and thereafter separating isobutylene, isobutyl alcohol and tertiary but'yl alcohol 'from the reacted mixture.

10. The method which comprises heating isobutyl chloride with at least its molecular equiv= alent 01' sodium hydroxide and sumcient water to dissolve saidhydroxide at superatmospheric pressure to a reaction'temperature above 100 C. and thereafter separating isobutylene, lsobutyl i0 alcohol and tertiary butyl alcohol'trom the reacted mixture.

11. The method which comprises heating a mixture of isobutyl chloride, water and calcium hydroxide at superatmospheric pressure to areaction temperature above 100 C. and thereafter separating isobutylene. isobutyl alcohol and tertiary butyl alcohol from the reacted mixture.

EDGAR c. BRI'I'ION. GERALD H. comm. GARNET! v. MOORE.