GB2113223A - Perfluorinated azabicyclodecanes - Google Patents

Abstract

Novel perfluorinated heterocyclic compounds have an azabicyclodecane structure with fused 5- and 7- membered rings incorporating a bridgehead nitrogen atom. They are prepared by cobalt (III) fluoride fluorination of quinolines or alkyl quinolines and are useful, when emulsified in aqueous media, as blood substitutes or organ perfusates, prior to transplant.

Description

SPECIFICATION Novel fluorinated heterocyclic compounds and their uses This invention relates to novel perfluorinated heterocyclic compounds and emulsions containing them.

There is a need for a functional liquid to serve as a blood substitute and as a perfusate for organ preservation prior to transplant. Such a liquid should have adequate oxygen-carrying capacity and the ability to emulsify in aqueous media but should not be hydrolysed or otherwise degraded in body tissues.

Compounds used in a commercial blood substitute, Fluosol DA (R.T.M.) are perfluorodecalin (which does not easily give a stable emulsion in aqueous media) and perfluorotripropylamine (which gives a more stable emulsion than perfluorodecalin, but which has a longer retention time in the body).

This invention, in the first aspect, consists in novel perfluoroheterocyclic compounds perfluoroazabicyclodecane, CgFt7N of boiling point 1270--1290C and its lower (1-2 C-atom) homologues.

It is believed that these new compounds have a 7-membered ring fused with a 5-membered ring in their structure, as shown below:

The nitrogen atom in the new compounds is connected to 3-carbon atoms i.e. it is in a bridgehead position. The preferred homologue is a compound with a trifluoromethyl group in the a- position i.e. attached to a carbon atom adjacent to the N-atom.

In a second aspect the invention consists in a method of producing perfluoro-azabicyclodecane and its lower (12 C-atom) homologues which method comprises reacting quinoline or an alkyl quinoline with a higher valent metal fluoride at 2500--4000C in an inert reactor to produce a fullyfluorinated product. During fluorination a shift of bonds takes place so that the nitrogen atom in the product is in a tertiary position giving a principal product with 5- and 7-membered rings fused together.

By a "higher valent metal fluoride" we mean a metal fluoride in a higher valency state such as cobalt (III) fluoride, CoF3 or CsCoF4 which is reduced to a lower valency state while acting as a fluorinating agent.

The product may be purified by fractional distillation and perfluoro-1 -azabicyclo(5,3,0)decane has the following physical properties: Boiling range 1270-1290C Refractive index at 220C nod2=1.3100 Specific gravity at 200C=1 .900 Pour point=-41 to42 C Solubilies at 250C Solubility of perfluoro- 1 azabicyclo(5,3,0)decane in Solvent 100 g solvent Water hardly soluble Hexane miscible Trichloro-trifluoroethane miscible Acetone 6.849 Methanol 1.36g In a third aspect the invention consists in an oil-in-water emulsion comprising perfluoro azabicyclodecane or a lower (1-2 C) homologue dispersed in an aqueous medium by means of a surface active agent. Preferably the surface active agent is non-ionic.

The invention will be further illustrated by the following Examples of the preparation of novel perfluoro-heterocyclic compounds in accordance with the invention.

Example 1 In a typical experiment, quinoline (150 g) was passed over cobalt (III) fluoride (10 kg) in a paddlestirred horizontal nickel reactor at 3500 (following the procedure in Advances in Fluorine Chemistry Vol. 1 p. 166) to give a crude liquid fluorocarbon (335 g) which was washed thoroughly with water and dried over calcium oxide. Fractional distillation of combined product from several fluorinations (in a 4 ft glass column with nickel Dixon gauzes) giave perfluoro-1-azabicyclo(5,3,0)decane CgF17N as a colourless liquid b.p. 127-1 290C (24.5% by wt. of the crude product). Neighbouring fractions contain some CgF17N mixed with other compounds.

Example 2 2-Methyl quinoline was fluorinated over cobalt (III) fluoride at 3200--3300C, following the procedure described in Example 1. The product was a clear colourless liquid (typically 212 g of product from 100 g of input). Product from several fluorination runs was combined, washed and dried over CaO and MgSO4. The mixture was fractionally distilled (3 ft glass column with nickel Dixon gauzes).

Fractional distillation gave a compound (b.p. 1460--1480C) for which 19F n.m.r. indicates the absence of N-CF3 groups and the presence of a C-CF3 group, which is consistent with a F3 group attached to a carbon atom adjacent to the bridgehead nitrogent atom. No N-F bonds were detected (from n.m.r.) and from its infra red spectrum the compound is clearly saturated. The relative molecular mass (by mass spectrometry) was 495 (C1OF,sN). The product is base-stable and its structure is constent with perfluoro- 1 -aza-2-methyl(5,3,0)decane.

The utility of the compounds according to the invention, as a blood-substitute or a perfusate for organic preservation will be illustrated as follows.

Potential use as an oxygen carrier for medical applications in comparison with perfluorodecalin (see for example U.S.P. 4,186,253).

1. Emulsion forming capacity To 10 ml of perfluoro-1 -azabicyclo(5,3,0)decane, (ABCD) was added 10 ml of solution made by dissolving 8.0 g of a non-ionic, polyoxyethylene-polyoxypropylene surfactant ('Pluronic F68', RTM) in 220 ml of deionised water. The mixture was emulsified for a few minutes using a high speed mixer to form an emulsion having the appearance of diluted milk. On standing at room temperature overnight, there was a minor amount of separation ('creaming') of the emulsion.

In a comparison test, an emulsion was formed using perfluorodecalin. An emulsion of similar appearance to that formed with ABCD required about 10 minutes emulsification. On standing overnight pronounced creaming occurred.

2. Oxygen solubility A portion of 20 ml of ABCD was degassed by boiling and cooled to 200C while being bubbled with oxygen gas. The oxygen-saturated liquid was then degassed under vacuum and the gas evolved was collected and its volume measured at a known temperature and pressure. After allowing for the vapour pressure of the fluorocarbon, the solubility of oxygen was calculated to be in the range 45+ 1 0 mls of O2 (at 760 mm Hg s OOC) per 100 ml of fluorocarbon. The solubility of oxygen in ABCD is thus adequate to permit the use of this fluorocarbon as an oxygen carrier for medical use.

3. Use of perfluoro-azebicyclodecane emulsions as blood-substitutes ABCD was evaluated as candidate for an artificial blood substitute from the aspects of toxicity, feasibility of emulsification and excretion rate from the organs.

Toxicity Wistar strain male rats administered with ABCD emulsion (dose as ABCD: 4 g/kg) gained weight favourably.

Stability of emulsion In order to evaluate the feasibility of emulsification, ABCD was emulsified with yolk phospholipids by using a Manton-Gaulin homogenizer and the stability to heating at 1000C for 30 minutes and storage at 40C and 250C for 2 weeks were examined. The emulsion was acceptably stable over these periods.

Excretion rate ABCD was very rapidly eliminated from the organs. 2 weeks after injection only trace amounts of ABCD were detected in all organs.

4. Retention of perfluoro-1 -azabicyclo(5,3,0)decane body organs with time Gas chromatography results-rats injected with emulsion of ABCD (0.32 ml fluorocarbon per 100 gm body weight). The following residual fluorocarbon concentrations were observed. (In mg fluorocarbon/gm tissue).

14 days 6 days (av.of2 5days lav. of2/ 10 days except*) 21 days Spleen 43.48 22.30 120.42 3.69* 1.12 Kidney 0.17 0.10 0.19 0.15 0.16 Liver 11.81 6.73 2.51 0.38 0.04 Lung 0.56 0.10 0.16 0.15 0.15 Heart 0.13 0.45 0.26 0.18 0.16

Claims (8)

Claims

1. A compound selected from perfluoro-azabicyclodecane and its 1-2 carbon atom perfluoroalkyl homologues.

2. A compound as claimed in claim 1 which has fused 5- and 7-membered rings and a bridgehead nitrogen atom in its structure.

3. A compound as claimed in claims 1 or 2 which has a trifluoromethyl group attached to a carbon atom adjacent to the bridgehead nitrogen atom.

4. A process for preparing a compound as claimed in claim 1 comprising heating quinoline or an alkyl quinoline to 2500--4000C in the presence of a fluoride of a metal in a higher valency state.

5. A process as claimed in claim 4 in which the higher valent metal fluoride is cobalt (III) fluoride

6. A process as claimed in claims 4 or 5 in which the temperature is within the range 300C 3500C.

7. An oil-in-water emulsion comprising a compound as claimed in claims 1, 2 or 3 when dispersed in an aqueous phase by means of a surface active agent.

8. An emulsion as claimed in claim 7 in which the surface active agent is non-ionic in character.