US2325422A - Process of making allo-ocimene - Google Patents

Description

I tratedj as follows:

Patented July 27, 1943" j VUNITED PATENT QFFICE' n 325,422 a i v rnocuss oFfrjrAmNq ALLo-oc'mE E V V T Robert c.'1 a1mer arid Carlisle I LBibb, Pensacola, 1 Fla assignors to Newport 'Industries,qInc.,

'- Pensa cola, Fla.,' a corporation of Delaware 7 No Drawingl Application December 23, 1940,

SerialNo. 371,410 8 Claims, (01. zen-m1) 'I'his' inventionrelatesftoa process for making allo-ocimene'by'thermalfdecoinposition oi alpha pinene. More particularly, the invention relates to a rupturing" of carbon to carbonlinkages in alpha-pinene under regulated, favorable thermal conditions with the formation of allo-ocimene.

The reaction,in accordance withwhichcarbon to carbon linkages in alpha-pinene are ruptured to form .allo-ocimene, may be graphically illusalpha-pinene allo-ocimene the rupture occurs only in the 4 carbon-ring, the

resulting product is dipentene. Actually, both allo-ocimene and dipentene are obtainedby the process of our invention.

b Although alpha-pinene is apparently stable at its boiling point of 156 C2, we'have'found that 7 when alpha-pinene in the liquid phase isheated to "temperatures" definitely above 156 0., the

fraction consisting largely of dipentene and another fraction consisting largely of allo-ocimen'e;

, the alpha-pinene in liquid phase at a tempera- 2o p vention will become apparent from the following alpha-pineneundergoes a structural change into V allo -ocimenef and dipentene. Allo-ocim'ene, however, being 'ahydroca'rbon containing 3- double bonds which are arranged in double conjugation, is "vryreactive, and it may be-lolst unless special precautions are taken for its'ipre's'ervation'n' For instance; when alpha-pinene I alone is heated for 2 hours in the liquidpha'se at" 250 C.,it isconl P vertedinito about 70% of monocyclic terpene'h drocarbons, largely dipentene,jandj2o% 'of high boiling polymers, with about "6% of the alphapinene remaining unreacted. The high boiling polymers are formed principally froma polymerization of allo-o'cimene.

We have now discovered that whenthe reac tion'is carried out by heatingthe-alphaminene dissolved in a relativ'ely high boiling diluent, relatively largeamounts of allo-ccimene can be re moved'f rom'the solution by steam distillation; while the amount of high boiling polymersis 'reduced from 20 to around 1 or 2%. The steam distillate can itself be fractionally. distilled into ture above; the'normal boiling point of alphapinenep It is a furtherimportantf object of this'inven tion to provide a process for making allo-ocimene by the thermal conversion of alpha pinene while avoiding the formation of substantial amounts of high boiling polymers. r

'It is a further important object of this invention to providea process for th thermal isomerization of alpha-pinene in liquid phase into alloocin' e'ne and dipentene, from the mixture of which allo-ocimene can be recovered by fractional distillation. V f i V Other and further important objects of this in description and appended claims. p The term dipentene as used in this specification'refers to thecheinical substance known as dl-limonene, namelya mixtureof dand l-limo nene. The word dipentene is used so loosely in the literature for describing various mixtures of monocyclicfl hydrocarbons which consist of the terpinenes, terpinolenes and sometimes little or no actual dipentene, that a chemical test must be made to determine whether what the literature has designated as dipentene is actually djpenproducts.

The following example will serve to illustrate aupref erred embodiment of our invention, but it will be understood that our invention is not limited, to the specific details of the example:

" Exampleilil'gals; of alphapinene were dissolved in 720' gels; of ahigh boiling,minerali oiljsuch as amineral oil having a boiling point of around 300 0., and heated to the boiling temperature of the solution 'for ,6 hours. lihe solution started to boil at 225 and heatingwas stopped when the temperature had jreached 240 C., whichtemperature was reached at the end of the 6 hour period." The mixture w'asithen steam distilled at 150 C. and 112.0 gals. of oil collected as distillate. The oil distillate had a specific gravity at /4 C. of 0.8%4 and a refractive-index at c. of 1.4855. 7 a

The alpha-pinene used as the starting material was prepared by the fractional distillation of wood turpentinegand when t stes; gave a spewcific'gravityat 15/4=-C of 0.361%, with a refractive index at 20 C. of 1.46760.

7 .The 112 gals. of oil collected distillate in the stearn distillation step were then,fn ctionallv distilled at 15 (absolute pressure of inercury) 7 using an efficient iractionating'icolumn. The results obtained are rec'orde'd in the fol lowing table:

ondinterm ate tract, n .wasrgcli The them-1h isoini ma be carried'p t Within a rather wi A ,1: fi e ajt ire 'b n fi e am r ureranee; the rate fof Lrea ti mere 5 fairly high, and M21609, 0., 'it s area as a relatively fast, with the "r'a e t me a m'eefi e 'i 'te ii e atwe}i lfiii d iltto 'defi fiifbe s of i manipulation l. H odlic sl i high temperatures, it 'rhay'he placed a'tar'oiind 400 C. on the basisiofvarious considerations. For ,the purpose of practicaloperation, thetemp'ejraturefo f the reaction should "be. Kept between lj'and 280'? (3., withthernostpreferred range atbet'vveen 225a'nd 25 050.} I

h While We havedesignatedialphagpinene,as the starting material, it is?practical to. use alfriiiiture of. aims-pinene and beta-pinene, s betapinene tends to change 'i v jl to, slim pmheji the'process and h'enlce, wiuib e agave; ,edm'tbhi; entene and alloocimene in the manner delii lsihce it contains pinene.

flsubieeted to,.the process herein described, the 'sifienes contained therein are converted into allo-ocirrier'iefand difi'entene.

scribed. When using beta-pinene alone, the re action was found to be much slower.

Thus, Where the term alpha-pinene is used in the claims, it will be understood that the alpha-pinene may either be the starting material 'or'it may he produced from the starting materialgili'iring tliqcarryi n'g o'ut'o'f the process de-' fined bythe claims. For instance, turpentine is an excellent raw material for use in our process, When turpentine is Consequently, any

' alpha-pineneproducing material, or any materia 1 remaining alpha-pinene, or pure alpha- 7 l pinene can be used as a starting material for our .pr s

Itvrill, of course, be understood that various details of the process may be varied through a b g' 5. Product Volume Q R. I. 20

Uni'eacted-alph'arpinene @8594 l. 1683 lstintermedietes 8540 1.14707 pigeiiteriejulin ;'.8446 1.5731

, the lpuri ose, to, li

' aw 'ei tbetweentai s 1250i 2- J99 n and-recovering the allo w g range without departing from the: princis. ;r l. ,i4tfi l,, ,g

p es ofthis in .e

otherwise than ecssi appended 1, Wefclaiin seem; liw A process of in s mpr s e t? li i phase ata terhberatur' ts [r a1; boiling oint until a substantial-Listeria i'q r S, id albhag pinene into allo-ocimene has taken place and recoveringallo-ocimene.

2. A process of making allo 'ocimene, which comprisesheating alpha-pinene in a high boiling solvent therefor in the liqui d phase to a temperature of between andAO'O C. to convert said alpha-pinenajnto allo-ocimene and 'dipentene and recoverin'gthe allo-ocimene. V

3. A process of making allo-ocimene ,,which comprises heating alpha pinene in a high Boiling solvent therefor in the liquid phaset'o a temperature ofbetween and 280 CQto convert said a p a-pimmamipsewense and ,dipentene nd m m Weir ne n? 7 e s t s alpha-pinene into all oi oc allo-ocimene and dipentene from said mineral oil, and recovering the allo-ocimene apart. from the dipentene by fractional distillation.

8. A process of making allo-ocimene which comprises heating a liquid containing alpha- 7 pinene at a temperature between 160 and 400 C. while maintaining the alpha-pinene in liquid phase until a substantiai proportion of said alpha-pinene has been converted into 2110- ocimene and dipentene, and recovering the a110- ocimene.

' ROBERT C. PALMER.

CARLISLE H. BIBBV