Sensitiveness to Moist Air

The crystalline salt obtained by action of phosphine on 68% perchloric acid at —20°C is dangerously explosive, sensitive to moist air, increase in temperature, or friction [1] and cannot be dried [2],... 

The pentahalides of niobium and tantalum are predominantly covalent. Their volatility decreases from the fluorides to the iodides. Nb and Ta belong to the few elements which form stable pentaiodides. Selected physical and thermodynamic properties for the halides are listed in Table 2. All are sensitive to moist air, water or hydroxylic solvents. 

Europium monoxide, EuO, is another ferromagnetic solid that may be used for studying the extrinsic field effect although the low Curie temperature restricts the usefulness of the results. Data are available (27) on two samples, one from the insulative part of the phase diagram with Tc = 69.3 1.0 K and surface 1.4 m2 g 1. (All samples of EuO are very sensitive to moist air and must be handled accordingly.) This sample is referred to below as EuO (ins). Another sample of EuO, from the conductive part of the diagram, had Tc = 129 3 K and surface 0.8 m2 g-1. This is referred to as EuO (con). 

Reaction of this A-chloro compound (99a-c) with triethylamine, tetra-methylethylamine, or 1,5-diazabicyclo [5.4.0] undec-5-ene resulted in the elimination of hydrogen chloride and the formation of the dehydrohydan-toins (lOOa-c). Evidence for the formation of the dehydrohydantoins was the precipitation of the amine hydrochlorite, the formation of 1,4-adducts with dienes and, in the case of (99b), the properties of the isolated products, (100b). All of the dehydrohydantoins are sensitive to moist air and are preferentially handled in an inert atmosphere. 

When red phosphorus is melted with selenium in a current of carbon dioxide a reaction is said to occur without notable loss of weight. The products are sensitive to moist air, phosphine and seleniuretted hydrogen being evolved. The action of concentrated alkalies or alkali selenides gives selenophosphates (q.v.).4... 

It is stated in the literature that the pure compound melts at r28°. It is very sensitive to moist air, which converts it into the free acid. 

Reaction of Fe(CO)2(NO)2 with KCN (1 2 mole ratio) in liq NH3 at 60°C under autogenous pressure yields green diamagnetic K2[Fe(CN)2(CO)(NO)2], formally containing Fe(2-) which is sensitive to moist air and must be handled in an inert atmosphere. 

Caution. Phenylboranes are very sensitive to moist air. The starting materials, reaction mixtures, and products must be kept under an inert gas at all times. 

Several 1-substituted 2(177)-pyrazinones (85) undergo [4 -I- 2] cycloaddition with ethene in toluene at 110°C to form bicyclic intermediates (86), the formation of which is more easy when the substituent X is a chloro, cyano, or thiocyanate group (Scheme 21). The adducts having an alkyl or aryl group as the substituent X are sensitive to moist air. Hydrolysis of the iminochloride... 

This bath has the advantage of operating at room temperature, but it is also very sensitive to moist air, forming highly corrosive and toxic HBr, and it has not been adopted by industry. 

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