Patent GB-561002-A (GB)
Title: Process for producing alkyl derivatives of branched chain paraffins
IPC: C07C2/62
Filed: 1942-11-24
Abstract: <FORM:0561002/IV/1> Alkyl derivatives of isoparaffins are produced by treating them with an alkyl fluoride in the presence of hydrogen fluoride.  The reaction may be effected at about - 10 to 75, preferably 0-30 DEG  C. and a pressure to maintain substantially liquid phase, with the isoparaffin in molar excess.  The reaction time is generally about 1-10 mins.  The alkyl fluorides may be prepared by the liquid phase reaction of an excess of anhydrous hydrogen fluoride, or that obtained as a by-product in the alkylation, at about - 60 to 100, preferably - 30 to 0 DEG  C., on olefines, in particular those present with paraffins, in a hydrocarbon fraction.  Unreacted paraffins may be separated from the resulting mixture of alkyl fluorides and excess hydrogen fluoride and this mixture used to alkylate isoparaffin in a second stage.  The separated paraffins may be fractionated to give an isoparaffin fraction for use in the alkylation.  In particular C3 and C4 olefines are converted into isopropyl and butyl fluorides and reacted with C4 and C5 paraffins to give products of gasoline boiling range.  A C4 fraction is fed by line 1, if desired with isobutane from line 7, to a reactor 6 under about 10 atm. pressure where it mixes with liquid hydrogen fluoride fed by lines 9 and 69.  A mixture of butyl fluorides and hydrogen fluoride leaves by line 14 for use in the alkylation.  Unconverted hydrocarbons leave by line 16, further amounts of fluorides being removed in separator 18, and pass to fractionator 23.  Overhead comprising isobutane, hydrogen fluoride, and possibly low boiling substances such as propane is led to receiver 29, where propane may be vented, and passed to the alkylation stage by line 14. Bottoms comprising n-butane are discharged by line 34 to fractionator 36 which separates n-butane as overhead from butyl fluorides and higher boiling hydrocarbons which pass to line 14. The mixture in line 14 is fed to an alkylator 44, preferably at about 20 DEG  C. and 11.5 atm.  Part of the reaction mixture is continuously withdrawn to separator 47 from which used hydrogen fluoride is discharged by line 69 and returned to reactor 6, and the hydrocarbon layer is fed to fractionator 57 where the hydrogen fluoride and propane present, together with some isobutane, leave as overhead while the alkylation product with isobutane leaves through line 76 and is separated in a further fractionator 78. The overhead from fractionator 57 is treated in separator 63 where propane is vented, hydrogen fluoride is returned by lines 66 and 69 to reactor 6 and, if desired, in part to alkylator 44, and a hydrocarbon layer is recycled by line 74 to the fractionator. The fractionator 78 separates isobutane which may be returned by lines 79 and 90 to alkylator 44, fractionator 23, and reactor 6, and alkylate which leaves by line 96.  If desired, the initial C4 fraction may be distilled to separate a bottom fraction comprising n-butane and butene-2 which is converted with hydrogen fluoride and then used for alkylating the overhead fraction comprising isobutane, isobutene, and butene-1.  In examples: (1) 2 molar proportions of isopropyl fluoride are introduced over 1 hr. into an autoclave containing anhydrous HF and isobutane, molar ratio 5 : 3.5, at 20 DEG  C.  Separation of the product yields a hydrocarbon mixture principally heptanes and other C5-C9 paraffins; (2) 3 molar proportions of a C4 fraction containing 30 per cent butenes are contacted with 50 of HF at -5 DEG  C. and the butyl fluorides and excess HF reacted with separated isobutane at 25 DEG  C.; (3) a C3 fraction is similarly reacted with excess of HF at 0 DEG  C. and the separated isopropyl fluoride and HF used to alkylate isobutane at 20 DEG  C.; (4) isopentane is used in the alkylation at 35 DEG  C. and 13.5 atm. of isopropyl fluoride prepared as in (3).  Specification 554,825 is referred to.