vogel_practical_ochem_3.pdf

896 PRACTICAL ORGANIC CHEMISTRY [VI,
The catalyst is finely-divided iron and is produced by adding a little crystallised
ferric nitrate and a slight excess of sodium to liquid ammonia ; the reaction is
probably :
2Fe(N03)3,9H20 + 42Na + 6NH3 —•
2Fe + 6Na2N02 + 24NaOH + 6NaNH2 + 9H2
A solution of mono-sodium acetylide in liquid ammonia is formed by passing
excess of acetylene gas into the suspension of sodamide :
Liquid NH.
2NaNH2 + HC^CH X NaC^CNa + 2NH8
Liquid NH.
NaC^CNa+HC^CH X 2NaC^CH»
Addition of n-butyl bromide then gives n-butylacetylene (1-hexyne) :
NaC=CH + 7i-C4H9Br LiQUid > w-C4H9C=CH + NaBr
NHa
Phenylacetylene is readily prepared by the dehydrohalogenation of styrene
dibromide with a solution of sodamide in liquid ammonia :
Liquid NIL CI
C6H6CHBr.CH2Br+3NaNH2 _J_-+ C6H6C^CNa U C6H5C^CH
Styrene dibromide KH% Phenylacetylene
The reaction between sodium acetylide in liquid ammonia solution and
carbonyl compounds gives a-acetylenyl carbinols (compare Section 111,148),
for example :
CH2 CH2 CH-
H, ,0 CO H„C C< H,C C<
I | NaCgCH 2 , j^C^CH NH,q ^ ». I \jsCH
I I inliq. NH, I I I I
HjC CH2
\ /
H4C CH»
\ /
HSC
\
CHj
/
CH2 CH2 CH2
ct/cZoHexanone l-Ethynylct/c/ohexanol
The acetylenic alcohol 4-pentyn-l-ol is conveniently prepared by treatment
of tetrahydrofurfuryl chloride with sodamide in liquid ammonia :
H2C CH2 H2C CH2
| | soci„ NaNH.in
H2CV ,CH—CH2OH c H N' H2CV XH—CH2C1 liquid NH.;
2 z C U JN
\ / « » \ / NH4C1
O 0
HC=CCH2CH2CH2OH
Tetrahydrofurfuryl alcohol 4-Pentyn-l-ol
* Monosodium acetylide may also be prepared by the reaction of acetylene with sodium
in liquid ammonia:
Liquid
2Na -f- 3HC=CH * 2NaC=CH + H.C»CH.
NH,
Some unreacted sodium may be left on the walls of the flask in this method and this may
partly reduce some product, such as an alkylacetylene, derived from the sodium acetylide.
The preparation of sodamide is not attended by much splashing and little (if any) unreacted
sodium remains on the walls of the flask. Although more manipulation and a somewhat
longer time is required for the sodamide method, the latter is generally preferred as it is
more adaptable and somewhat less troublesome.