2,6-di-tert-butylphenols

Details 2,6-di-tert-butylphenols 2,6-di-tert-butylphenols

1997-10-10

2002-09-03

Wu, Shean C. (Department: 1756)

Stock material or miscellaneous articles

Liquid crystal optical display having layer of specified...

C252S299610, C252S299630, C252S299500, C544S298000, C544S336000, C549S369000, C560S067000, C560S075000, C568S784000

Reexamination Certificate

active

06444278

ABSTRACT:

The present invention relates to 2,6-di-tert-butylphenols of the formula I
in which
R is H, an alkyl or alkenyl radical having 1 to 18 carbon atoms which is unsubstituted or substituted by CN or by at least one halogen, e.g., up to perhalo-substituted, and in which one or more non-adjacent CH
2
groups may be replaced by a radical selected from the group consisting of —O—, —S—, —CO—, —O—CO—, —CO—O— and —C≡C—,
A
1
and A
2
are, independently of one another,
a) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N,
b) a 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH
2
groups may be replaced by —O— or —S—,
c) a piperidine-1,4-diyl, a 1,4-bicyclo[2.2.2]-octylene or naphthalene-2,6-diyl radical,
where the radicals a) and b) may be monosubstituted or polysubstituted by halogen atoms,
Z
1
and Z
2
are each, independently of one another, —CO—O—, —O—CO—, —CH
2
—O—, —OCH
2
, —CH
2
CH
2
—, —CH═CR—, —C≡C— or a single bond, and
m and n are each, independently of one another, 0, 1, 2 or 3, where m+n≧1,
with the proviso that compounds of the formulae
are excluded.
BACKGROUND OF THE INVENTION
Since autoxidation can result in a considerable drop in value of many natural products, for example foodstuffs and natural rubber, and, industrial products, for example monomers for polymerization purposes, petroleum products and plastics, the search for substances which prevent or retard autoxidation in the lowest possible concentration has become a broad area of research.
The phenolic antioxidants used today in industry are phenols which are substituted in the ortho-position to the hydroxyl group, usually by bulky groups. The action of these sterically hindered phenols is based on the ready liberation of the phenolic hydrogen atom with formation of phenoxide free radicals.
The use of antioxidants relates essentially to the stabilization of oils, fats and plastics. Antioxidants for these purposes must not be toxic, should have high effectiveness at low concentrations, should not cause any changes in taste, odor or color, even on extended storage or heating, should be readily soluble or easily dispersible in the substrate, should not exert any adverse effect on the substance to be protected, should have low volatility, and should allow analytical determination as quantitatively as possible.
Furthermore, antioxidants should be simple and inexpensive to prepare, and their handling and incorporation should be simple.
The prior art contains phenolic antioxidants of the formulae
However, the antioxidants mentioned do not satisfy all requirements. A particular disadvantage is that the antioxidants mentioned must be employed in relatively high concentrations.
SUMMARY OF THE INVENTION
An object of the present invention was therefore to find inexpensive antioxidants which satisfy all the conditions mentioned.
Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art.
Surprisingly, it has now been found that the 2,6-di-tert-butylphenols of the formula I have high effectiveness as antioxidants, even at low concentrations, without exerting any adverse effect on the substance to be protected. Furthermore, the novel sterically hindered phenols are distinguished by heat resistance, low viscosity and low volatility.
The invention thus relates to 2,6-di-tert-butylphenols of the formula I.
The claimed compounds are free-radical scavengers and are therefore suitable for suppressing ageing processes caused by free-radical chain reactions, such as, for example, autoxidation.
Owing to their structure, these materials have a particularly low vapor pressure and can thus also be employed at high temperatures. They and their reaction products are colorless and thus do not result in any discoloration of the materials to be stabilized.
For reasons of simplicity, phenol below denotes
Cyc denotes a 1,4-cyclohexylene radical, Che denotes a 1,4-cyclohexenylene radical, Dio denotes a 1,3-dioxane-2,5-diyl radical, Dit denotes a 1,3-dithiane-2,5-diyl radical, Phe denotes a 1,4-phenylene radical, Pyd denotes a pyridine-2,5-diyl radical, Pyr denotes a pyrimidine-2,5-diyl radical and Bi denotes a bicyclo[2.2.2]octylene radical, where Cyc and/or Phe may be unsubstituted or monosubstituted or disubstituted by F.
The compounds of the formula I accordingly include bicyclic compounds of the subformulae Ia and Ib:
R—A
1
—A
2
—phenol
Ia
R—A
1
—Z
1
—A
2
—phenol
Ib
tricyclic compounds of the subformulae Ic to Ig:
R—A
1
—A
1
—A
2
—phenol
Ic
R—A
1
—Z
1
—A
1
—Z
1
—A
2
—phenol
Id
R—A
1
—Z
1
—A
1
—A
2
—phenol
Ie
R—A
1
—A
1
—Z
1
—A
2
—phenol
If
R—A
1
—A
1
—A
2
—Z
2
—phenol
Ig
and tetracyclic compounds of the subformulae Ih to Io:
R—A
1
—A
1
—A
1
—A
2
—phenol
Ih
R—A
1
—Z
1
—A
1
—A
1
—A
2
—phenol
Ii
R—A
1
—A
1
—Z
1
—A
1
—A
2
—phenol
Ij
R—A
1
—A
1
—A
1
—Z
1
—A
2
—phenol
Ik
R—A
1
—Z
1
—A
1
—Z
1
—A
1
—A
2
—phenol
Il
R—A
1
—Z
1
—A
1
—A
1
—A
1
—Z
1
—A
2
—phenol
Im
R—A
1
—A
1
—Z
1
—A
1
—Z
1
—A
2
—phenol
In
R—A
1
—Z
1
—A
1
—Z
1
—A
1
—Z
1
—A
2
—phenol
Io
Of these, particular preference is given to those of the subformulae Ia, Ib, Ic, Id, Ie and If.
In the compounds of the formula I, Z
1
and Z
2
are preferably a single bond or CH
2
CH
2
, secondarily preferably —CH
2
O—, —OCH
2
—, —O—CO— or —CO—O—.
If one of the radicals Z
1
and Z
2
is —(CH
2
)
4
— or —CH═CH—CH
2
CH—, the other radical Z
1
or Z
2
(if present) is preferably a single bond.
The sun n+m is preferably 1 or 2.
If R is an alkyl radical and/or an alkoxy radical, this can be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6 or 7 carbon atoms and accordingly is preferably ethyl, propyl, butyl, pentyl, hexyl,. heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy, furthermore methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradecoxy.
Oxaalkyl, i.e., having a CH
2
group replaced by —O—, is preferably straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.
If R is an alkyl radical in which one CH
2
group has been replaced by —CH═CH—, this can be straight-chain or branched. It is preferably straight-chain and has 2 to 10 carbon atoms. Accordingly, it is in particular vinyl, prop-1- or -2-enyl-, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, or dec-1-, -2-, -3-, -4-, 5-, -6-, -7-, -8- or -9-enyl.
If R is an alkyl radical in which one CH
2
group has been replaced by —O— and one has been replaced by —CO—, these are preferably adjacent. These thus contain one acyloxy group —CO—O— or one oxycarbonyl group —O—CO—. These are preferably straight-chain and have 2 to 6 carbon atoms.
Accordingly, they are in particular acetoxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, acetoxymethyl, propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetoxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetoxypropyl, 3-propionyloxypropyl, 4-acetoxybutyl, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, propoxycarbonylmethyl, butoxycarbonylmethyl, 2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl, 2-(propoxycarbonyl)ethyl, 3-(methoxycarbonyl)propyl, 3-(ethoxycarbonyl)propyl or 4-(methoxycarbonyl)butyl.
If R is an alkyl radical in which one CH
2
group has been replaced by unsubstituted or substituted —CH═CH— and an adjacent CH
2
group has been replaced by CO or CO—O or O—CO—, this can be straight-chain or branched. It is preferably straight-chai

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