DETAILED DESCRIPTION OF THE INVENTION The various groups represented by the symbols have the meanings defined below and these definitions are retained throughout this specification.
The lower alkyl groups are straight or branched chain hydrocarbon groups containing 1 to 8 carbon atoms, preferably 1 to 4 carbons.
Examples of the type of these groups are methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, isopentyl, etc.
The phenyl-lower alkyl groups include such lower alkyl groups attached to a phenyl (or two phenyl groups), e.
g.
, benzyl, phenethyl, benzhydryl, etc.
The salt forming ions represented by R are metal ions, e.
g.
, alkali metal ions such as sodium or potassium, alkaline earth metal ions such as calcium or magnesium, or an amine salt ion, of which a number are known for this purpose, for example, lower alkylamines like methylamine or triethylamine, aralkylamines like dibenzylamine, N,N-dibenzylethylenediamine, N-ethylpiperidine, etc.
Preferred embodiments of this invention are as follows: R is hydrogen, alkali metal, trimethylsilyl or ##STR6## especially hydrogen, pivaloyloxymethyl, sodium or potassium, R.
sub.
5 is lower alkyl.
R.
sub.
1 is hydrogen, lower alkyl of 1 to 4 carbons, phenyl, furyl or thienyl, especially hydrogen and phenyl.
R.
sub.
2 and R.
sub.
6 each is hydrogen or lower alkyl of 1 to 4 carbons, especially hydrogen.
R.
sub.
3 is lower alkyl, especially methyl, or phenyl.
R.
sub.
4 is thiadiazole, tetrazole and their methyl substituted analogs, especially, 1,3,4-thiadiazole, 5-methyl-1,3,4-thiadiazole, tetrazole and 1-methyltetrazole.
The new derivatives of [(thioalkyl)thioacetyl]-cephalosporins of this invention are produced by reacting 7-aminocephalosporanic acid (7-ACA) (or derivatives wherein R.
sub.
3 is other than hydrogen) with a mercaptan HS-R.
sub.
4 at a pH of about 8 - 8.
5 to obtain the derivative of the formula ##STR7## The product of formula II is then acylated on the amino group with a [(thioalkyl)thio]acetic acid of the formula or an activated derivative of the former (II)
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Semiconductor manufacture 
