US2023565A - Manufacture of musk xylene - Google Patents

Description

Patented Dec. 10, 1935 UNITED STATES PATENT OFFICE.

MANUFACTURE OF MUSK XYLENE Walter V. Wirth, Woodstown, N. J., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing.

Application February 1, 1934.

Serial No. 709,287

3 Claims.

NOa- N 0 2 Q:- CH;

which is known as musk xyelene.

Musk-xylene has heretofore been manufac-.

tured by nitrating tertiary-butyl-meta-xylene (1,3-dimethy1-S-tertiary-butyl-benzene) in a two- 7 step process involving the use of fuming nitric acid and 25% oleum in succession. (Ullmann, Enzyklopaedie der technischen Chemie, 1st edition, vol 9, page 615.) This process not only involves theme of costly acids, but its yield is relatively low, being in the order of in the process reported. This process has also the further disadvantage that it requires the use of costly, special-metal or enameled apparatus, due to the high concentration of the reagents employed, and suifers in general from the inconvenience and hazard attendant upon the use of fuming acids. 7

It is accordingly an object of this invention to provide an improved and economical process for the nitration of tertiary-butyl-meta-xylene. It is a further object of this inventionto provide a process for the nitration of tertiary-butyl-metaxylene, whereby the desired product, musk-xylene, is obtained in exceptionally high yield. Other and further important objects of this invention will appear as the description proceeds.

I have found that tertiary-butyl-meta-xylene can be nitrated eflectively and efiiciently by the aid of mixed nitrating acid. Moreover, I have found that when a mixture of nitric and sulfuric acids is used as opposed to the fuming nitric and fuming sulfuric acid of the previous art, the yield is considerably increased, approaching the theoretical.

My improved process accordingly consists of reacting upon tertiary-butyl-meta-xylene with a mixed nitrating acid, that is a mixture of nitric and sulfuric acids. The concentration of nitric acid in the mixture may vary within wide limits, for instance between 12 and 50% by weight of the mixture. For practical reasons it is advan- More particularly it relates tageous to use nitrating mixtures as occur in commerce.

I found that the ratio of nitric acid to that theoretically required with a given quantity of tertiary-butyl-m-xylene need not be so excessive a as indicated in the literature. In the process disclosed in Ullmann, above cited, an excess of 83% of nitric. acid was employed. In my process satisfactory results are obtained with substantially theoretical quantities. Excesses, however lO do no harm, and the process may be practiced in general with from 3 to '6 mols. of nitric per mol. of the hydrocarbon.

My improved process enables the reaction to-be carried out in standard cast iron apparatus. It 15 also eliminates the inconvenience and hazard of handling fuming nitric and sulfuric acids. Finally, in my process the hydrocarbon and nitrating mixture may be mixed in one step, as opposed to the successive addition of the two reagents in the process reported by Ullmann. Without limiting my invention to any particular procedure, the following examples are given to illustrate my preferred mode of operation. Parts given are by weight. 7 5.

Example 1 A cast iron kettle, equipped with an agitator, heating and cooling jacket, etc., was charged with r 800 parts of a commercial -mixed acid, contain- 7 ing 70% H2SO4 and 30% HNOs .27 times theory of nitric acid). 162 parts of tertiary-buty'l-me xylene (1 mol.) were added gradually over a period of 1 hours, keeping the temperature of the nitration mass at 33 to 3 5 C. The mass was 35 then heated to 110 C. over a period of hour; and kept at 110-112 C. for 3 hours. At this point the crystalline reaction product became molten and remained'as an oil until cooling was applied. The mass was cooled gradually to C. V V over'a period of 1 hour'to obtain well-formed Theproduct was purified by crystallizing twice I from 1900 parts of alcohol; 261.4 parts' of pure musk xylene were obtained, melting at 113.4 55

The crude musk xylene crystals were fil- 45 I to 113.8 C., which corresponds to 88% of theory on the basis of the initial material.

Example 2 162 parts of tertiary-butyl-m-xylene were added gradually to 730 parts of mixed acid (50% HNO3+50% H2804) over a period of 1 hours, keeping the temperature under 20 C. The mass was heated to C. over /2 hour and held at 70 C. for 3 hours. It was cooled at 30 C. and worked up as in Example 1. 291 parts of crude musk xylene were obtained.

Example 3 162' parts of tertiary-butyl-m-xylene were added gradually to 357 parts of mixed acid (50% I-INO3-l-50% H2304) over a period of 1 hour, keeping the temperature at 25-30 C. The mass was stirred for 15 minutes at 25-30 C. and then 324 parts of mixed acid (12.6% I-INO3-l-87% H2SO4) were added over a period of 20 minutes, keeping the nitration mass at 25-30 C. Finally, 162 parts of the latter mixed acid were added over 15 minutes, while allowing the temperature to rise to 40 C. The nitration mass was stirred at 40 C. for 10 minutes and heated to C. over hour. It was cooled to 70 C. over A; hour and held at 70 C. for two hours. After that, it was cooled to 30 C., and worked up as in Example 1. 291 parts of crude musk xylene were obtained, or 98% of theory.

It will be understood that the processes above set forth are susceptible of variation within wide limits, as regards the amounts of mixed acid used, the percentage of nitric and sulfuric in the mixed acids, the temperature of nitration and the time required to add the components. It will be further understood that the invention is not limited to the use of anhydrous mixed acid. Any of the hydrated commercial grades may be used; for instance, the grade consisting of or the grade 12:80:8; except that a larger quantity of 'the nitrating agent will be required to oifset the weaker nitrating power of the acid due to dilution with water.

It will also be understood that it is not necessary to crystallize the reaction product in the nitrator before drowning the nitration mass. The hot nitration mass, in which the musk xylene is in the molten condition, may be added slowly to ice water to granulate the product. Furthermore, it will be understood that in case insuflicient mixed acid is used to complete the nitration in one step, more mixed acid of various strengths can be added after the addition of the tertiary- 5 butyl-m-xylene and in case the original mixed acid is too weak in sulfuric acid to drive the reaction to completion, more sulfuric or'fuming sulfuric acid may be added after the addition of the hydrocarbon. 10

The advantages of my improved process will now be readily apparent.

First, my process is carried out in one step, Where the art required the addition of nitric and sulfuric acids in two separate steps. Second- 15 1y, I use the cheaper commercial mixed acid where the art called for expensive fuming nitric and fuming sulfuric acids. Thirdly, the required excess of nitric acid for efiicient working is much less in my process than in the art (27% as com- 20 pared to 83%). Fourthly, the handling of mixed. acid is considerably more convenient and .less hazardous than the handling of fuming acids, and the apparatus required is of the standard castiron type. Finally, the yield is much higher in 25 my process than in that described in the literature. Moreover, the crude obtainable in my process is of such excellent quality that it may be purified directly from-alcohol, whereas the prior art found it necessary to purify first from 3,0.

acid, containing between 12.6 and 50% by weight 45 of :nitric acid.

3. In the process of producing musk-xylene, the step which comprises adding gradually tertiary-butyl-m-xylene to a commercial grade of mixed nitric and sulfuric acid at a tempera- 50 ture of about 20 to 40 C., and then raising the temperature to about '70 to 112 C., "to complete the reaction.

WALTER V. WIRTI-I.