Oxygen, with alcohols

Accdg to Tschitikel (Ref 2), some V-2 rockets were driven by a mixt of liquid oxygen with alcohol contg some w, which was added in order to keep the flame temp as Low as possible to avoid damage to the... 

The mechanism of exchange of oxygen with alcohols can conveniently be discussed as a function of the structure of the carbon skeleton. In the elucidation of the mechanism, studies of the absolute and comparative rates of exchange can be used as well as the rates of loss of optical activity and of various competing rearrangements in alcohols of suitable structure. Hence a large number of studies have centred on secondary and tertiary alcohols, where the stereochemistry can be studied by different means, and less attention has been paid to primary alcohols. 

Oxidation of ethylene in alcohol with PdCl2 in the presence of a base gives an acetal and vinyl ether[106,107], The reaction of alkenes with alcohols mediated by PdCl2 affords acetals 64 as major products and vinyl ethers 65 as minor products. No deuterium incorporation was observed in the acetal formed from ethylene and MeOD, indicating that hydride shift takes place and the acetal is not formed by the addition of methanol to methyl vinyl etherjlOS], The reaction can be carried out catalytically using CuClj under oxygen[28]. 

Carboxylic acids are the most acidic class of compounds that contain only carbon hydro gen and oxygen With s of about 5 they are much stronger acids than water and alcohols The case should not be overstated however Carboxylic acids are weak acids a 0 1 M solution of acetic acid m water for example is only 1 3% ionized... 

Reaction with Oxygen Nucleophiles. In the presence of strong acids, eg, H2SO4, HBF, or BF, aziridines react with alcohols to form P-amino ethers (93) ... 

Many older finishes can be removed with single solvents or blends of petroleum solvents and oxygenates. Varnish can be removed with mineral spirits, shellac can be stripped with alcohols, and lacquers can be removed with blends of acetates and alcohols (lacquer thinners). The removal mechanism is one of dissolving the coating, then washing the surface or wiping away the finish. This method is often used to reamalgamate or liquefy old finishes on antique items of furniture. 

The principal impurity in potassium metal is sodium. Potassium s purity can be accurately deterrnined by a melting point test (Fig. 2) or atomic absorption if necessary after quenching with alcohol and water. Traces of nonmetallic impurities such as oxygen, carbon, and hydrogen can be deterrnined by various chemical and physical methods (7,8). 

The 1990 Clean Air Act mandates for blended oxygenates ia gasoline created a potentially large new use for DIPE as a fuel oxygenate. Isopropyl alcohol can react with propylene over acidic ion-exchange (qv) catalysts at low temperatures, which favor high equiUbrium conversions per pass to produce DIPE (34). 

Oxygen-Gontaining Organics. Neutral and anionic oxygen-containing organic molecules form complexes with thorium. Recent work has focused on alkoxides (72), aryloxides, and carboxylates however, complexes with alcohols, ethers, esters, ketones, aldehydes, ketoenolates, and carbamates are also well known. 

The alkylboranes obtained by the hydroboration reaction are versatile intermediates for further transformations. The most important transformation is the oxidation to yield alcohols 17 it is usually carried out by treatment with hydroperoxide in alkaline solution. The group R migrates from boron to oxygen with retention of configuration ... 

Aldehydes and ketones undergo acid-catalyzed reaction with alcohols to yield heniiacetals, compounds that have one alcohol-like oxygen and one ether-like oxygen bonded to the same carbon. Further reaction of a hemiacetal with alcohol then yields an iicetal, a compound that has two ether-like oxygens bonded to the same carbon. 

Hurley and Testa (Ref 17) exposed nitrobenzene in isopropyl alcohol, degassed and in air, to a mercury lamp at 3660A Products in the absence of air were acetone and phenyl-hydroxylamine (PHA). In air PHA was oxidized to nitro sob enzene which couples with PHA to form azoxybenzene. They hypothesized that the triplet molecule abstracted H-atoms from the solvent no effect was noted with ben zene as solvent. They also worked with nitrobenzene in isopropyl alcohol-water mixts containing HC1 with a mercury lamp at 3660A (Ref 18), and found that the quantum yields depended on pH and isopropyl alcohol content, but were independent of oxygen with acid present. Their conclusion was that the quantum yield consisted of two parts, H abstraction by the triplet, and protonation of the triplet... 

Here the alcoholic hydroxyl is first protonated and then eliminated as water. The allylcarbenium ion (2) is initially stabilized by elimination of the proton at C-14. Then the ether link is opened after protonation of the ring oxygen with the formation of carbenium ion (3), whereby the neighboring C-C bond of the piperidine ring is cleaved with aromatization of the C ring. The carbenium ion (4) formed is stabilized by elimination of a proton and ring closure to apomorphine (5). 

This type of catalyst is not limited to nickel other examples are Raney-cobalt, Raney-copper and Raney-ruthenium. When dry, these catalysts are pyrophoric upon contact with air. Usually they are stored under water, which enables their use without risk. The pyrophoric character is due to the fact that the metal is highly dispersed, so in contact with oxygen fast oxidation takes place. Moreover, the metal contains hydrogen atoms and this adds to the pyrophoric nature. Besides the combustion of the metal also ignition of organic vapours present in the atmosphere can occur. Before start of the reaction it is a standard procedure to replace the water by organic solvents but care should be taken to exclude oxygen. Often alcohol is used. The water is decanted and the wet catalyst is washed repeatedly with alcohol. After several washes with absolute alcohol the last traces of water are removed. 

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