CA1053668A - Synthesis of sterically hindered ketoximes and their iminoxy radicals - Google Patents
Synthesis of sterically hindered ketoximes and their iminoxy radicalsInfo
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- CA1053668A CA1053668A CA225,161A CA225161A CA1053668A CA 1053668 A CA1053668 A CA 1053668A CA 225161 A CA225161 A CA 225161A CA 1053668 A CA1053668 A CA 1053668A
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- adamantyl
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Abstract
Abstract of the Disclosure A low pressure process for producing sterically hindered ketoximes from the appropriate ketimines has been developed. Sym-metrical and unsymmetrical ketimines are produced by reaction of a tert-alkyl nitrile with a tert-alkyllithium, followed by hydro-lysis of the formed lithium dialkyl ketimine. Symmetrical dial-kyl imines are also formed from tert-alkyl mitriles and sodium, followed by hydrolysis. The imines need not be isolated but can be directly converted to ketoximes by oxidation with hydroxyl-amine hydrochloride. Further oxidation of the ketoximes yields sterically hindered dialkyl iminoxy radicals having relatively good stability.
Description
The syntheS~ of oximes of highly hindered ketones is difficult because the reactions giving rise to them are extreme-ly slow under ordinary conditions. Derivatives of such ketones have been pre~ared in the past by use of forcing conditions that include long reaction times and high temperatures and pressures.
This requires extensive, special equipment, not available in most laboratories and the method is not suitable for the preparation of large amounts of product. A method employing such forcing conditions has been described by W.~l. Jones and E.W. Tristram in United States Patent No. 3,256,331 issued June 14, 1966. That patent describes a method for making, inter alia, oximes, from compounds having unreactive carbonyl groups, with nitrogenous carbonyl addition reagents under pressures in the order of 50 9 000 to 150,000 p.s.i. In order to effect the reaction at such pres-sures, the patent describes the use of compressible stainless steel sample holders which are placed in high pressure reaction vessels and thencompressed hydraulically.
The synthesis of ~ tert butyl ketimine by reacting pi-valonitrile in a sodium dispersion, and its conversion into the hydrazone and p-toluenesulfonylhydrazone has been recently des-cribed (H.D. Hartzler, J. Amer. Chem. Soc. 93, 4527 (1971).
That paper however does not describe the production of the cor-responding oxime or give any indication of how it may be produced.
The addition of tert-butyllithium to pivalonitrile has been described by M.R. Collier et al. (J. Chem. Soc. (Dalton Transactions) 1972, 370)); however, the intermediate lithium ad-duct was used in a reaction unrelated to the preparation of imines, oximes or iminoxy radicals.
It has been recently discovered that a hindered di-tert-butyl oxime can be oxidized to give an iminoxy radical of moder-ate stability (Brokenshire, Mendenhall, and Ingold, J. Amer. Chem.
- 1 - '~' Soc., 93, 5278 (1971)). Such radicals are similar to the nitroxide radicals obtained from hydroxylamines. Many experimental and practical uses of nitroxides have been realized, e.g. as spin-labels in molecules of biological interest, as inhibitors of vinyl polymerizations, or inhibitors of hydrocarbon oxidation, and as one component of magnetometers for measuring magnetic fields.
Radicals of the iminoxy class will have similar uses.
According to the present invention, oximes of the general formula R - C~ - R
N - OH
(I) and their corresponding iminoxy radicals of the general formula R - C - R
N - O- (II) where R and R' in formulas I and II are tert-alkyl or cyclo-alkyl groups and may be the same or different, may be synthesized by reacting a nitrile of the formula R'CN with an alkyllithium com~ound of the formula RLi, where R and R' are as defined above, and converting the resultant product to the desired oxime or imi-noxy radical by the successive steps of hydrolysis, treatment of the reaction mixture with hydroxylamine hydrochloride, and (where the iminoxy radical is required) oxidation. The reaction pro-ceeds as follows:
R CN + RLi~ R-C--R 2 5 ~) R-C-R
N-Li NH
R-C-R ~ - -- R-C-R ~ E~OAc NH OH HCl N~ N~ 2 OH
It can be seen that since R and R' need not be identical, the synthesis can be directed to give a product with any two desired ~ 053668 alkyl grou~s attache~ to the imine group. I-ligh reaction pressures and temperatures are not required. When symmetrical di-tert-alkyl ketoximes or iminoxy radicals are required they can also be prepared by reaction of a tert-alkyl nitrile with so~ium, follow-ed l)y hydrolysis: +
H ACOH
2RCN + 2Na~ R-C-R + NaCN ~, R-C-R ~ ) R-C-R
NH20H HCl ~1 NNa NH M-OH
where R is as defined above. High reaction pressures and temperatures are similarly not required.
Adamantyl oximes and their iminoxy radicals are of parti-cular interest and can be prepared according to this process. The iminoxy radicals thus prepared have relatively good stability.
Suitable tert-alkyl and cycloalkyl groups according to the present invention include tert-butyl and higher alkyl analogues thereof, monocyclic alkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl groups, bi-cyclic alkyl groups such as bi-cyclo 2.1.1 hexyl, bi-cyclo 2.2.1. heptyl, bi-cyclo 2.2.2. octyl; tri-cyclic alkyl groups such as tri-cyclo 3.2.1Ø octyl, di-spiro 4.1.5.2. tetradecyl and di-spiro 5.S.1.3. hexadecyl; and cross-linked cycloalkyl groups such as adamantyl.
The present invention is described in more specific de-tail by reference to the following examples.
EXAMPLE
Preparation of Di-tert-butyl ketoxime 40 ml of a solution of 1.25 M tert-butyllithium in n-pentane, (Foote Mineral Co.~, was placed in a flask under a ni-trogen atmosphere, and 4.1 g (50 mmol) of pivalonitrile was add-ed dropwise from an additional funnel. This mixture was stirred magnetically during this time. After the mixture stood for 1 hour at 25Q, there were added successively 5 ml of absolute ethanol, ~ 053668 3 ml of acetic acid 3.5 g of hydroxylamine hydrochloride. An additional 65 ml of ahsolute ethanol was uscd to transfer the mixture to a flask with a condenser attached, and the mixture was refluxed 5 hours. About 25 ml of water was added, and the mix-ture was coolcd in ice. The colorless crystals were filtered off, sucked partly dry, and sublimed under about 1 mm pressure.
The yieid was 3.3 g (46%) (sublimes lS~ ; mp 157.5-158.5 ).
Preparation of Di-tert-butyl iminoxy Di-tert butyl ketoxime (0.3 g in 30 ml of benzene) was stirred or shaken 90 min. with 0.7 g of silver oxide (Fisher) to give a blue solution that was filtered and concentrated at 25 .
The resulting oil (0.22 g, 74~) was distilled twice in vacuo by the bulb-to-bulb technique with the receiver in liquid nitrogen:
fp-21 ; n21D 1.4452; d 0.82 ; Anal. Calcd for CgH18NO;
C, 69.18; Il, 11.61; N, 8.97, mol wt, 156.24. Found: C, 68.96;.
H, 11.77; N, 9.15; mol wt, 160 (vapor pressure osmometry in ben-zene at 37).
; 20 Preparation of Di-adamantyl ketoxime ~irst the corresponding di-adamantyl ketimine was prepar-ed according to the method of J. H. Wieringa et al., Tetrahedron Letters, No. 20, P. 2073. Their procedure was a modification of that of H. D. Harzler, (J. Amer. Chem. Soc. 93, 4527 (1971).
11.0 g (68.2 mmol) of l-adamantyl carbonitrile was dis-solved in 600 ml of sodium dried n-hexane and the solution was filtered to remove insoluble material. 14.0 g of a 50% sodium dispersion in paraffin ~ax was added (about 304 mmol of sodium).
The above mixture was refluxed under argon for 10 hours.
At the end of this time the excess sodium was destroyed by the dropwise add-tionof 60 ml of water.
In this example, the ketimine was isolated and purified 105366~
via its hydrochlori~e. The cru~e yield of imine was 7.0 g (70~).
Recrystallization from n-hexane gave 4.4. g of di-adamantyl keti-mine as a white powder (mp 140 - 143C).
3.0 g (10 mmol) of this di-adamantyl ketimine was dissolv-ed in 150 ml of absolute ethanol together with 0.65 ml of glacial acetic acid and 0.70 g (10 mmol) of hydroxylamine hydrochloride.
This solution was refluxed for one hour and then stirred at room temperature for six hours.
The solution was vacuum filtered to give snow white cry-stals, and the crystals were pumped mechanically for one hour.
Yield: 2.8 g (88%); mp= 268-271C. Anal. Calcd: for C21H31NO: C, 80.46; H, 9.97; N, 4.47. Found: C, 80.63; H, 10.03;
N, 4.40. This compound, i.e. the di-adamantyl ketoxime ca~ also be prepared from the adamantyllithium and adamantylnitrile follow-ing the procedure of Example 1.
Preparation of Di-adamantyl iminoxy radical (Reference - Mendenhall and Ingold, (J. Amer. Chem. Soc.
95, 2963 tl973)). Di-adamantyl ketoxime prepared according to Example 3 (1.0 g partially dissolved in 900 ml of benzene) was stirred for 21 hours with 1.50 g of silver oxide to give a pale green solution.
The reaction was followed by esr and was found to be ; completed after 5 hours.
The solution was filtered and concentrated at 25 C giv-ing a crystalline green product.
The solid was dissolved in n-hexane and a white material was removed. The remaining green solution was passed through a 25 x 80 mm column of Woelm "Dry Column" SiO2. This separated the product into a yellow material which remained at the top of the column and a blue material (the radical) which ran through the column fairly easily. The hexane solution, now blue in colour, was filtered and concentrated at 25 C to a pale blue solid.
Weight: 0.518 g ~51.6~); mp = 121-122.5 C.
Anal: Calcd: for C21H30N0: C, 80.72; H, 9-68; N~ 4-48-Found: c~ 80.59; Il, 9.69; N, 4.37.
Preparation_of tert-butyl-l-adamantyl ketoxime 0.81 g l-adamantanonitrile (5 mmol) were dissolved in 50 cc absolute ethyl ether in a flask which had been flushed with argon. 5.5. cc of 1.25M tert-butyllithium ~Foote Mineral Co.) in n-pentane (6.9 mmol) were added all at once at 25C through a serum cap to that solution. After this mixture had stood for 10 minutes at 25C, there were added successively O.S cc of ab-solute ethanol, 0.3 cc of acetic acid and 0.35 g of hydroxylamine hydrochloride in 20 cc of absolute ethanol. The mixture was transferred to reflux apparatus in which the bulk of the ethyl ether was distilled off. The mixture was refluxed five hours at 70C, and allowed to stand for three days. Colourless crystals were filtered off, washed with ethanol and sucked dry. 0.43 g of product was obtained.
A second crop of product was obtained on dilution of the filtrate with water and standing at 5C. The second crop of cry-stals was filtered off and sucked dry. The yield was 0.31 g, giving a total yield of 0.74 g ~63%)(sublimes 203 C, mp 202-203C).
Anal. Calcd: for C15H24NOH: C, 76.54; H, 10-71; N~ 5.95.
Found: C, 76.41; ~, 10.74; N, 5.87.
Preparation of tert-b_tyl-l-adamantyl iminoxy radical 0.05 g of crude tert-butyl-l-adamantyl ketoxime prepared according to Example 5 in 10 cc of benzene was stirred ten hours with 0.20 g silver oxide. The solution was filtered and the pro-~6-duct was puriied by recrystallization from solutions of i-pentane and absolute ethanol cooled to -78C. 32.7 mg tert-butyl adamantyl iminoxy was obtained as a bluc crystalline product (mp 45-47GC;
yicld 65%).
The solid sterically hindered cycloalkyl iminoxy radi-cals prepared according to the present invention appear to be particu~ ~ stable radicals. For example, the di-adamantyl imi-noxy radical is completely stable at room temperature in the air for at least three months. Tert-butyl-l-adamantyl iminoxy radi-cal is similarly very stable. In solution, these radicals are less stable, as is also the situation with the liquid di-tert-butyl iminoxy. These radicals are the first stable a (sigma) radicals known to have been prepared. All other known stable radicals (e.g. nitroxides, DPP~I, triphenylmethyl, etc.) are of the ~ (pi) type. This novel feature in a stable radical will give iminoxy radicals special uses that cannot even be foreseen at the present time.
This requires extensive, special equipment, not available in most laboratories and the method is not suitable for the preparation of large amounts of product. A method employing such forcing conditions has been described by W.~l. Jones and E.W. Tristram in United States Patent No. 3,256,331 issued June 14, 1966. That patent describes a method for making, inter alia, oximes, from compounds having unreactive carbonyl groups, with nitrogenous carbonyl addition reagents under pressures in the order of 50 9 000 to 150,000 p.s.i. In order to effect the reaction at such pres-sures, the patent describes the use of compressible stainless steel sample holders which are placed in high pressure reaction vessels and thencompressed hydraulically.
The synthesis of ~ tert butyl ketimine by reacting pi-valonitrile in a sodium dispersion, and its conversion into the hydrazone and p-toluenesulfonylhydrazone has been recently des-cribed (H.D. Hartzler, J. Amer. Chem. Soc. 93, 4527 (1971).
That paper however does not describe the production of the cor-responding oxime or give any indication of how it may be produced.
The addition of tert-butyllithium to pivalonitrile has been described by M.R. Collier et al. (J. Chem. Soc. (Dalton Transactions) 1972, 370)); however, the intermediate lithium ad-duct was used in a reaction unrelated to the preparation of imines, oximes or iminoxy radicals.
It has been recently discovered that a hindered di-tert-butyl oxime can be oxidized to give an iminoxy radical of moder-ate stability (Brokenshire, Mendenhall, and Ingold, J. Amer. Chem.
- 1 - '~' Soc., 93, 5278 (1971)). Such radicals are similar to the nitroxide radicals obtained from hydroxylamines. Many experimental and practical uses of nitroxides have been realized, e.g. as spin-labels in molecules of biological interest, as inhibitors of vinyl polymerizations, or inhibitors of hydrocarbon oxidation, and as one component of magnetometers for measuring magnetic fields.
Radicals of the iminoxy class will have similar uses.
According to the present invention, oximes of the general formula R - C~ - R
N - OH
(I) and their corresponding iminoxy radicals of the general formula R - C - R
N - O- (II) where R and R' in formulas I and II are tert-alkyl or cyclo-alkyl groups and may be the same or different, may be synthesized by reacting a nitrile of the formula R'CN with an alkyllithium com~ound of the formula RLi, where R and R' are as defined above, and converting the resultant product to the desired oxime or imi-noxy radical by the successive steps of hydrolysis, treatment of the reaction mixture with hydroxylamine hydrochloride, and (where the iminoxy radical is required) oxidation. The reaction pro-ceeds as follows:
R CN + RLi~ R-C--R 2 5 ~) R-C-R
N-Li NH
R-C-R ~ - -- R-C-R ~ E~OAc NH OH HCl N~ N~ 2 OH
It can be seen that since R and R' need not be identical, the synthesis can be directed to give a product with any two desired ~ 053668 alkyl grou~s attache~ to the imine group. I-ligh reaction pressures and temperatures are not required. When symmetrical di-tert-alkyl ketoximes or iminoxy radicals are required they can also be prepared by reaction of a tert-alkyl nitrile with so~ium, follow-ed l)y hydrolysis: +
H ACOH
2RCN + 2Na~ R-C-R + NaCN ~, R-C-R ~ ) R-C-R
NH20H HCl ~1 NNa NH M-OH
where R is as defined above. High reaction pressures and temperatures are similarly not required.
Adamantyl oximes and their iminoxy radicals are of parti-cular interest and can be prepared according to this process. The iminoxy radicals thus prepared have relatively good stability.
Suitable tert-alkyl and cycloalkyl groups according to the present invention include tert-butyl and higher alkyl analogues thereof, monocyclic alkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl groups, bi-cyclic alkyl groups such as bi-cyclo 2.1.1 hexyl, bi-cyclo 2.2.1. heptyl, bi-cyclo 2.2.2. octyl; tri-cyclic alkyl groups such as tri-cyclo 3.2.1Ø octyl, di-spiro 4.1.5.2. tetradecyl and di-spiro 5.S.1.3. hexadecyl; and cross-linked cycloalkyl groups such as adamantyl.
The present invention is described in more specific de-tail by reference to the following examples.
EXAMPLE
Preparation of Di-tert-butyl ketoxime 40 ml of a solution of 1.25 M tert-butyllithium in n-pentane, (Foote Mineral Co.~, was placed in a flask under a ni-trogen atmosphere, and 4.1 g (50 mmol) of pivalonitrile was add-ed dropwise from an additional funnel. This mixture was stirred magnetically during this time. After the mixture stood for 1 hour at 25Q, there were added successively 5 ml of absolute ethanol, ~ 053668 3 ml of acetic acid 3.5 g of hydroxylamine hydrochloride. An additional 65 ml of ahsolute ethanol was uscd to transfer the mixture to a flask with a condenser attached, and the mixture was refluxed 5 hours. About 25 ml of water was added, and the mix-ture was coolcd in ice. The colorless crystals were filtered off, sucked partly dry, and sublimed under about 1 mm pressure.
The yieid was 3.3 g (46%) (sublimes lS~ ; mp 157.5-158.5 ).
Preparation of Di-tert-butyl iminoxy Di-tert butyl ketoxime (0.3 g in 30 ml of benzene) was stirred or shaken 90 min. with 0.7 g of silver oxide (Fisher) to give a blue solution that was filtered and concentrated at 25 .
The resulting oil (0.22 g, 74~) was distilled twice in vacuo by the bulb-to-bulb technique with the receiver in liquid nitrogen:
fp-21 ; n21D 1.4452; d 0.82 ; Anal. Calcd for CgH18NO;
C, 69.18; Il, 11.61; N, 8.97, mol wt, 156.24. Found: C, 68.96;.
H, 11.77; N, 9.15; mol wt, 160 (vapor pressure osmometry in ben-zene at 37).
; 20 Preparation of Di-adamantyl ketoxime ~irst the corresponding di-adamantyl ketimine was prepar-ed according to the method of J. H. Wieringa et al., Tetrahedron Letters, No. 20, P. 2073. Their procedure was a modification of that of H. D. Harzler, (J. Amer. Chem. Soc. 93, 4527 (1971).
11.0 g (68.2 mmol) of l-adamantyl carbonitrile was dis-solved in 600 ml of sodium dried n-hexane and the solution was filtered to remove insoluble material. 14.0 g of a 50% sodium dispersion in paraffin ~ax was added (about 304 mmol of sodium).
The above mixture was refluxed under argon for 10 hours.
At the end of this time the excess sodium was destroyed by the dropwise add-tionof 60 ml of water.
In this example, the ketimine was isolated and purified 105366~
via its hydrochlori~e. The cru~e yield of imine was 7.0 g (70~).
Recrystallization from n-hexane gave 4.4. g of di-adamantyl keti-mine as a white powder (mp 140 - 143C).
3.0 g (10 mmol) of this di-adamantyl ketimine was dissolv-ed in 150 ml of absolute ethanol together with 0.65 ml of glacial acetic acid and 0.70 g (10 mmol) of hydroxylamine hydrochloride.
This solution was refluxed for one hour and then stirred at room temperature for six hours.
The solution was vacuum filtered to give snow white cry-stals, and the crystals were pumped mechanically for one hour.
Yield: 2.8 g (88%); mp= 268-271C. Anal. Calcd: for C21H31NO: C, 80.46; H, 9.97; N, 4.47. Found: C, 80.63; H, 10.03;
N, 4.40. This compound, i.e. the di-adamantyl ketoxime ca~ also be prepared from the adamantyllithium and adamantylnitrile follow-ing the procedure of Example 1.
Preparation of Di-adamantyl iminoxy radical (Reference - Mendenhall and Ingold, (J. Amer. Chem. Soc.
95, 2963 tl973)). Di-adamantyl ketoxime prepared according to Example 3 (1.0 g partially dissolved in 900 ml of benzene) was stirred for 21 hours with 1.50 g of silver oxide to give a pale green solution.
The reaction was followed by esr and was found to be ; completed after 5 hours.
The solution was filtered and concentrated at 25 C giv-ing a crystalline green product.
The solid was dissolved in n-hexane and a white material was removed. The remaining green solution was passed through a 25 x 80 mm column of Woelm "Dry Column" SiO2. This separated the product into a yellow material which remained at the top of the column and a blue material (the radical) which ran through the column fairly easily. The hexane solution, now blue in colour, was filtered and concentrated at 25 C to a pale blue solid.
Weight: 0.518 g ~51.6~); mp = 121-122.5 C.
Anal: Calcd: for C21H30N0: C, 80.72; H, 9-68; N~ 4-48-Found: c~ 80.59; Il, 9.69; N, 4.37.
Preparation_of tert-butyl-l-adamantyl ketoxime 0.81 g l-adamantanonitrile (5 mmol) were dissolved in 50 cc absolute ethyl ether in a flask which had been flushed with argon. 5.5. cc of 1.25M tert-butyllithium ~Foote Mineral Co.) in n-pentane (6.9 mmol) were added all at once at 25C through a serum cap to that solution. After this mixture had stood for 10 minutes at 25C, there were added successively O.S cc of ab-solute ethanol, 0.3 cc of acetic acid and 0.35 g of hydroxylamine hydrochloride in 20 cc of absolute ethanol. The mixture was transferred to reflux apparatus in which the bulk of the ethyl ether was distilled off. The mixture was refluxed five hours at 70C, and allowed to stand for three days. Colourless crystals were filtered off, washed with ethanol and sucked dry. 0.43 g of product was obtained.
A second crop of product was obtained on dilution of the filtrate with water and standing at 5C. The second crop of cry-stals was filtered off and sucked dry. The yield was 0.31 g, giving a total yield of 0.74 g ~63%)(sublimes 203 C, mp 202-203C).
Anal. Calcd: for C15H24NOH: C, 76.54; H, 10-71; N~ 5.95.
Found: C, 76.41; ~, 10.74; N, 5.87.
Preparation of tert-b_tyl-l-adamantyl iminoxy radical 0.05 g of crude tert-butyl-l-adamantyl ketoxime prepared according to Example 5 in 10 cc of benzene was stirred ten hours with 0.20 g silver oxide. The solution was filtered and the pro-~6-duct was puriied by recrystallization from solutions of i-pentane and absolute ethanol cooled to -78C. 32.7 mg tert-butyl adamantyl iminoxy was obtained as a bluc crystalline product (mp 45-47GC;
yicld 65%).
The solid sterically hindered cycloalkyl iminoxy radi-cals prepared according to the present invention appear to be particu~ ~ stable radicals. For example, the di-adamantyl imi-noxy radical is completely stable at room temperature in the air for at least three months. Tert-butyl-l-adamantyl iminoxy radi-cal is similarly very stable. In solution, these radicals are less stable, as is also the situation with the liquid di-tert-butyl iminoxy. These radicals are the first stable a (sigma) radicals known to have been prepared. All other known stable radicals (e.g. nitroxides, DPP~I, triphenylmethyl, etc.) are of the ~ (pi) type. This novel feature in a stable radical will give iminoxy radicals special uses that cannot even be foreseen at the present time.
Claims (17)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing sterically hindered oximes of the general formula (I) where R and R' are tertiary alkyl, cycloalkyl or cross-linked cycloalkyl groups and are the same or different, which comprises:
(a) reacting a nitrile of the formula R'CN with one of (i) an alkyllithium compound of the formula RLi, where R and R' are as defined above, and (ii) for symmetrical oximes where R will be the same as R' in the final product, sodium, and (b) converting the reaction product to the oxime of formula I by hydrolysis followed by treat-ment with hydroxylamine hydrochloride.
(a) reacting a nitrile of the formula R'CN with one of (i) an alkyllithium compound of the formula RLi, where R and R' are as defined above, and (ii) for symmetrical oximes where R will be the same as R' in the final product, sodium, and (b) converting the reaction product to the oxime of formula I by hydrolysis followed by treat-ment with hydroxylamine hydrochloride.
2. A process according to claim 1 which comprises the addi-tional step of oxidizing the oxime produced to the corresponding iminoxy radical of the formula (II)
3. A process according to claim 1 for the preparation of an oxime of the general formula I which comprises reacting a nitrile of the formula R'CN with an alkyllithium compound of the formula RLi, and converting the reaction product to the oxime of formula I by hydrolysis followed by treatment of the reaction mixture with hydroxylamine hydrochloride.
4. A process according to claim 1 for the preparation of an oxime of the general formula I where R and R' are the same, which comprises reacting a nitrile of the formula R'CN with sodium and reacting the ketimine thus produced with hydroxylamine hydro-chloride to produce the corresponding oxime.
5. A process according to claim 2 wherein silver oxide is the oxidizing agent.
6. A process according to claim 1 wherein the reaction with hydroxylamine hydrochloride to produce the oxime of formula I
takes place in the presence of ethanol and acetic acid.
takes place in the presence of ethanol and acetic acid.
7. A process according to claim 1 wherein R and R' are se-lected from the group consisting of tert-butyl and higher analo-gues thereof, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, bi-cyclo 2.2.1 hexyl, bi-cyclo 2.2.1 heptyl, bi-cyclo 2.2.2 octyl, di-spiro 4.1.5.2 tetradecyl, di-spiro 5.5.1.3 hexadecyl and ada-mantyl.
8. A process for the preparation of di-tert-butyl ketoxime according to claim 3, which comprises reacting pivalonitrile with tert-butyllithium.
9. A process according to claim 6 which comprises adding suc-cessively to the reaction mixture ethanol, acetic acid and hydro-xylamine hydrochloride, and then refluxing the reaction mixture and isolating and purifying the ketoxime produced.
10. A process for the preparation of tert-butyl-adamantyl ketoxime according to claim 3 which comprises reacting adamanta-nonitrile with tert-butyllithium.
11. A process according to claim 10 which comprises adding successively to the reaction mixture ethanol, acetic acid and hy-droxylamine hydrochloride and then refluxing the reaction mixture and isolating and purifying the tert-butyl-adamantyl ketoxime.
12. A process according to claim 10 which comprises oxidiz-ing the tert-butyl-adamantyl ketoxime produced to form the tert-butyl-adamantyl iminoxy radical.
13. A process for the preparation of di-adamantyl ketoxime according to claim 1 which comprises the steps of reacting 1-adamantyl carbonitrile in a sodium dispersion adding succes-sively acetic acid and hydroxylamine hydrochloride to this re-action product dissolved in ethanol, and then refluxing the reaction mixture and isolating and purifying the di-adamantyl ketoxime produced.
14. A process for the preparation of di-adamantyl ketoxime according to claim 1 which comrpises reacting adamantyllithium and adamantylnitrile.
15. A process according to claim 13 which comprises the addi-tional step of oxidizing the di-adamantyl ketoxime to form the adamantyl iminoxy radical.
16. A process according to claim 14 which comprises the addi-tional step of oxidizing the di-adamantyl ketoxime to form the adamantyl iminoxy radical.
17. A stable sterically hindered iminoxy radical of the for-mula II as illustrated in claim 2, wherein R and R' are selected from the group consisting of tertiary alkyl and cycloalkly groups, and R and R' are not both tertiary alkyl.
18. Di-1,1'-adamantyl iminoxy radical according to claim 17.
19. Tert-butyl-1-adamantyl iminoxy radical according to
17. A stable sterically hindered iminoxy radical of the for-mula II as illustrated in claim 2, wherein R and R' are selected from the group consisting of tertiary alkyl and cycloalkly groups, and R and R' are not both tertiary alkyl.
18. Di-1,1'-adamantyl iminoxy radical according to claim 17.
19. Tert-butyl-1-adamantyl iminoxy radical according to
claim 17.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US46468274A | 1974-04-26 | 1974-04-26 |
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| CA1053668A true CA1053668A (en) | 1979-05-01 |
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| CA225,161A Expired CA1053668A (en) | 1974-04-26 | 1975-04-22 | Synthesis of sterically hindered ketoximes and their iminoxy radicals |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5134183A (en) * | 1990-10-22 | 1992-07-28 | Ciba-Geigy Corporation | Sterically hindered oxime color improvers for polyolefin processing |
| US5266726A (en) * | 1990-10-22 | 1993-11-30 | Ciba-Geigy Corporation | Sterically hindered oxime color improvers for polyolefin processing |
-
1975
- 1975-04-22 CA CA225,161A patent/CA1053668A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5134183A (en) * | 1990-10-22 | 1992-07-28 | Ciba-Geigy Corporation | Sterically hindered oxime color improvers for polyolefin processing |
| US5266726A (en) * | 1990-10-22 | 1993-11-30 | Ciba-Geigy Corporation | Sterically hindered oxime color improvers for polyolefin processing |
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